# Overall power distribution



## CliffyJ (Apr 29, 2009)

I'm thrashing around with my spreadsheet on planned and potential power loads, and am trying to get to max probable vs. max theoretical, in the hopes of subpanel sizing. Or, whether I can just bring 8 or 10 20A circuits from my existing dual 200A boxes in the basement. All this is leading up to an estimate, from an electrical contractor, next fall. So no hurry. But I'm trying to plan a sort of "power center", what it is comprised of, and how much room to leave for the equipment (in the garage). And THAT"S what I need to plan for now.

This issue doesn't matter _right _now, because I'll be hooking things up temporarily. But for planning purposes, I'm trying to figger this thing out. And I need to rearrange my garage for proper real estate for these power critters. (Thanks Greg, for your prior posts on how you laid things out).

I'm probably being stupid, because my "ultimate" circuit presupposes that I'll be building this thing until I'm 80 years old... very unlikely... but even ten years from now, I'm not gonna want to find that I'd done something really dumb ~now. 

Here's an example of what I'm trying to understand. Some of my big theoretical consumers are the 10A amps.... (Now here I go, showing just how ignorant I am) Those are peak amps, depending on how much load is drawing upon them, right? If you plug one in, with no load, there's nothing, right? So overall, can I plan on a max number of loco's at X amps each (say, 6 x 4), resulting in (say) 2 15A circuits each feeding 3 (say) amplifiers each? Or, do I need to put in a 20A circuit for each pair of 10A amplifiers?

I understand that the breaker sizing has to do with protecting the wiring, but I'm having problems with subpanel sizing...
Also, FWIW, I'm trying to (at least in theory) accommodate grounds lighting, building lighting, SPFX, work / utility receptacles, under-deck maintenance lights, etc. So I'm trying to make my spreadsheet accommodate likelihood of load, depending on certain scenarios. 

To cut to the chase, does anyone have a spreadsheet you can email me, along the same lines? Or have some insights, from what I've described?

Thanks in advance for any wisdom,
====Cliff


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## Greg Elmassian (Jan 3, 2008)

Cliff, remember if you are doing 10 amps at 24 volts, then that is 2 amps at 110... assuming you have a switching power supply. 

So one 10 amp circuit would result in about 50 amps for the layout at 24 volts, so there's no reason to put in a lot of circuits. 

Greg


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## CliffyJ (Apr 29, 2009)

Posted By Greg Elmassian on 17 Mar 2011 05:00 PM 
Cliff, remember if you are doing 10 amps at 24 volts, then that is 2 amps at 110... assuming you have a switching power supply. 

So one 10 amp circuit would result in about 50 amps for the layout at 24 volts, so there's no reason to put in a lot of circuits. 

Greg Thanks Greg. 

These questions began as an email to you, but then I thought it should be all laid out there, ignorance and all... I'm wishing I'd just sent that email though, this is really embarrasing!










Even so, I'll trade reputation (such as it is...) for knowledge any day. And you've hit on a key thing for me, so bear with me as I try to get this thing rock solid. 

Let's say I have a 8A 12vdc effects / signal amp, for each of four (theoretical) phases/sections of the layout, and the consumers have an expected max usage rate of 25%. If I'm reading you correctly, I can use this equation: 

(12v/110v) * 8A * 4 *.25

for a circuit load total of .87A @ 110vac.

??

Cheers,
===Cliffy


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## CliffyJ (Apr 29, 2009)

So here's another one. 

Let's say I have 30 incandescent bulbs, per theoretical quantity of 4 layout sections, at 25 watts and 12 volts, to light a bunch of structures. And I need to figure out what they're going to draw, at the 110V panel level. Yes, LED's are great, but I need to understand this basic equation, because I'm just not getting it. 

Using A = W/V, 

25W/12V = 2.08A (per bulb). But that's at 12V. 

So to convert that to 110, per the prior posts, I tried this: 

A =25W/(12v/110v) = 230, which is obviously wrong. 

Is the bulb manufacturer declaring the watts, as if the bulbs were being run on 110V? If so, the equation would be: 

A =25W/110v = .23A (per bulb), which is what I've been using for planning. But now I'm not sure... 

Gosh, I feel so stupid posting this... but thanks Greg / all for lending a hand, and maybe someone else might benefit









===Cliff


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## krs (Feb 29, 2008)

Posted By CliffyJ on 18 Mar 2011 02:04 PM 

Let's say I have a 8A 12vdc effects / signal amp, for each of four (theoretical) phases/sections of the layout, and the consumers have an expected max usage rate of 25%. If I'm reading you correctly, I can use this equation: 

(12v/110v) * 8A * 4 *.25

for a circuit load total of .87A @ 110vac.

??

Cheers,
===Cliffy


It's not quite that simple.

For one, Greg mentioned a switching power supply and for simplicity assumed 100% efficiency when converting from line voltage to a lower voltage.

Actual efficiency is always lower than that, for switching supplies typically around 85%, maybe a bit better, for linear supplies much lower.
So the actual circuit load at the secondary will be higher than what you calculated - how much higher depends on the particular supply used.

Knut


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## krs (Feb 29, 2008)

Posted By CliffyJ on 18 Mar 2011 02:44 PM 
So here's another one. 

Let's say I have 30 incandescent bulbs, per theoretical quantity of 4 layout sections, at 25 watts and 12 volts, to light a bunch of structures. And I need to figure out what they're going to draw, at the 110V panel level. Yes, LED's are great, but I need to understand this basic equation, because I'm just not getting it. 

Using A = W/V, 

25W/12V = 2.08A (per bulb). But that's at 12V. 

So to convert that to 110, per the prior posts, I tried this: 

A =25W/(12v/110v) = 230, which is obviously wrong. 

Is the bulb manufacturer declaring the watts, as if the bulbs were being run on 110V? If so, the equation would be: 

A =25W/110v = .23A (per bulb), which is what I've been using for planning. But now I'm not sure... 

Gosh, I feel so stupid posting this... but thanks Greg / all for lending a hand, and maybe someone else might benefit









===Cliff 


Yes, a 25 watt 12 volt bulb will draw a steady state current of 2.08 amps as you calculated.
If you had a 110volt to 12 volt power supply that was 100% efficient, the current draw per bulb from the 110 volt supply would be 12/110 * 2.08 or 0.227 amps.

With a powe supply at 85% efficience, the current would become 0.267 amps per bulb. (divide the 0.227 by 0.85)

But with incandescent bulbs you may also have to consider the inrush current. That's the momentary current required when you first turn the light on.


Knut


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## CliffyJ (Apr 29, 2009)

Hi Knut, thanks for replying to this. 

I'm fine with sizing the loads up, for the efficiency factor; great point.


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## Greg Elmassian (Jan 3, 2008)

There's probably enough "give" in the power supply to handle it, either a slow blow fuse, or a filter cap. 

But as you can see, the amps will add up on the 12v/24v side.... for many reasons, start thinking LEDs .... 

Greg


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## CliffyJ (Apr 29, 2009)

Posted By krs on 18 Mar 2011 04:19 PM 
Posted By CliffyJ on 18 Mar 2011 02:44 PM 
So here's another one. 

Let's say I have 30 incandescent bulbs, per theoretical quantity of 4 layout sections, at 25 watts and 12 volts, to light a bunch of structures. And I need to figure out what they're going to draw, at the 110V panel level. Yes, LED's are great, but I need to understand this basic equation, because I'm just not getting it. 

Using A = W/V, 

25W/12V = 2.08A (per bulb). But that's at 12V. 

So to convert that to 110, per the prior posts, I tried this: 

A =25W/(12v/110v) = 230, which is obviously wrong. 

Is the bulb manufacturer declaring the watts, as if the bulbs were being run on 110V? If so, the equation would be: 

A =25W/110v = .23A (per bulb), which is what I've been using for planning. But now I'm not sure... 

Gosh, I feel so stupid posting this... but thanks Greg / all for lending a hand, and maybe someone else might benefit









===Cliff 


Yes, a 25 watt 12 volt bulb will draw a steady state current of 2.08 amps as you calculated.
If you had a 110volt to 12 volt power supply that was 100% efficient, the current draw per bulb from the 110 volt supply would be 12/110 * 2.08 or 0.227 amps.

With a powe supply at 85% efficience, the current would become 0.267 amps per bulb. (divide the 0.227 by 0.85)

But with incandescent bulbs you may also have to consider the inrush current. That's the momentary current required when you first turn the light on.


Knut 


Thanks, Knut!! That really helps me out!

So probably the next "duh" thing need to do in my spreadsheet is back off the per-model-building watts to, say, 5. That will help the numbers out...

Sheesh, I'm dense,

===Cliffy


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## CliffyJ (Apr 29, 2009)

Posted By Greg Elmassian on 18 Mar 2011 04:24 PM 
There's probably enough "give" in the power supply to handle it, either a slow blow fuse, or a filter cap. 

But as you can see, the amps will add up on the 12v/24v side.... for many reasons, start thinking LEDs .... 

Greg 
Roger the LED's Greg, the incandescents are now the primary consumers across the board (in my theoretical arrangement).

ThanksDude,

CJ


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## Greg Elmassian (Jan 3, 2008)

I have a passenger train with 3 locos... the 3 locos draw about 3.5 amps total, the 8 passenger cars draw 6.2 amps... incandescent bulbs... 

Greg


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## krs (Feb 29, 2008)

Cliffy, 

I think you're worrying too much about the 25 watt incandescent bulbs to light structures. 
Incandescents are pretty much the most inefficient light bulbs you can buy - most of the electrical energy is converted into heat, not light. 
There are much more efficient light sources available depending on the voltage and the type of lamp and socket you end up using - and I don't just mean LEDs. 

And another comment - the number of watts is the electrical enery a device consumes. It's pretty much independent of voltage. 
So you don't have to calculate the current of a 25 watt bulb takes at 12 volts and then convert that to the current at 110 volts - you can just calculate the current at 110 volts directly using the formula you posted above. 

Knut


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## CliffyJ (Apr 29, 2009)

Posted By krs on 18 Mar 2011 05:31 PM 
Cliffy, 

I think you're worrying too much about the 25 watt incandescent bulbs to light structures. 
Incandescents are pretty much the most inefficient light bulbs you can buy - most of the electrical energy is converted into heat, not light. 
There are much more efficient light sources available depending on the voltage and the type of lamp and socket you end up using - and I don't just mean LEDs. 

And another comment - the number of watts is the electrical enery a device consumes. It's pretty much independent of voltage. 
So you don't have to calculate the current of a 25 watt bulb takes at 12 volts and then convert that to the current at 110 volts - you can just calculate the current at 110 volts directly using the formula you posted above. 

Knut Yes, yes and yes.

I'm now planning (for circuit calcs at least) to light my structures with LED rope lights. I've used them on one job in the past, so eariler this afternoon I looked them up again: the super-brights are ~7W per foot, and couple of feet in a large mine structure should do well. Or at least, might. Regardless, that cut my loads down dramatically.

Thanks for your clarifying the watts at whatever voltage!

Here's my current circuit summary (for planned work, and the stuff I'd like to do if I reach 110 years of age...!)


*Summary* CKT Panel Source Amps Breakr Max 1 Grounds Lighting 1 W23 10 7.3 2 W25 15 9.1 3 W27 15 9.1 4 W29 15 9.1 2 Utility Receptacles 5 W28 15 12.0 3 Track Power 6 E26 15 9.8 4 Signal / Effects 7 E28 15 9.8 5 Model Lighting 8 E29 10 6.8 9 E30 15 8.9 81.9

Anything look wacky?

===Cliff


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## krs (Feb 29, 2008)

Posted By CliffyJ on 19 Mar 2011 02:06 PM 


*Summary* CKT Panel Source Amps Breakr Max 1 Grounds Lighting 1 W23 10 7.3 2 W25 15 9.1 3 W27 15 9.1 4 W29 15 9.1 2 Utility Receptacles 5 W28 15 12.0 3 Track Power 6 E26 15 9.8 4 Signal / Effects 7 E28 15 9.8 5 Model Lighting 8 E29 10 6.8 9 E30 15 8.9 





81.9

Anything look wacky?




Hard to tell since we don't know your overall plan.

I thought your railroad was in a garage - so what do you mean by "grounds lighting" - accent lighting for the front and back yard that has nothing to do with the railroad?


I'm also not clear what you mean by "model lighting" Is that the lighting for just the model structures and other stationary lighting?
Lighting for the model trains including lighting in any cars would come from track power.

Signal/Effects - 10 amps...seems to be a lot if that is just for the railroad

Bottom line - I can't tell if anything is "wacky" with the information provided.

Overall it sounds like an awful lot of power for these type of things.

Knut


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## CliffyJ (Apr 29, 2009)

Hi Knut, 

Yeah, I only posted that diagram to show how the circuit arrangement was shaping up so far, and was wondering if you or Greg saw something massively surprising. 

I see that I should have explained my terms, I apologize; and let me clarify. 

The layout is to be outdoors, but the "power center" (X-10-like devices, main circuit switches, NCE equipment, dimmers, etc.) is to be in the garage. 

In a way, this is a continuation of a thread I started last December, the result of which convinced me to put the gear in the garage. Check Greg's equipment out (about the middle of page 2): 

http://www.mylargescale.com/Communi.../34/aft/118535/afv/topic/afpgj/1/Default.aspx 

So for "grounds lighting," I refer to a variety of things, some 12V, some 110V outdoor floods (mounted in a few big trees, and with dimmers in the garage). The latter, as you'd expect, are the heavy hitters. And perhaps that's my next big "power mining" project, to see if there are low-voltage / LED alternatives to standard 110v PAR lamps (?). 

The "model lighting" circuits are for internal illumination of a number of large building models -- the heart of the layout. These will be big; and there will be (God willing) a representation of Virginia City. At the moment, for rough calcs, I'm planning on a certain quantity of LED rope light per major structure or structure group. 

"Signal / effects" is for whatever I feel like doing in 12v SPFX, and aux signal where needed. However, now that I'm powering switch machines from DCC/rail power directly, I need to revisit those potential loads. 

The loads appear quite high, because I'm sizing things here for a really extensive layout... about 5 times large than what I'm up to. I know that I'll probably not live that long, or have the funds. But the layout planning, even in theory, has been a great joy to me. So.... 

In planning for the hear and now, I've decided to size the power feeds to the "power center" (in the garage) just in case I win the lottery or something  And that affects whether to plan on a subpanel, or just snake feeds from my existing boxes in the basement, to the garage, as needed. 

So you've given me great feedback, and made me think some more. You've done precisely as I'd hoped. 

Best regards, 

===Cliffy


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## CliffyJ (Apr 29, 2009)

Guys, 

I'd like this year to make about 12 outdoor lamps for my deck, using real hurricane lamps with (perhaps) 12vac 40w incandescent bulbs (e.g., http://1000bulbs.com/category/decorative-chandelier-12-and-24-volt-light-bulbs ). It would be nice if the system was dimmable. 

Questions: 

1. Would you use a dimmer package from Malibu? 

2. Or... might I attempt a simple transformer, and can I just put a standard 600w dimmer to its input? 

3. If the former, I haven't been able to find Malibu dimmer unit max amps (in 110v, vs. 12v watt capacity), have you? Probably not saying that right... 

4. Or, would you spend the bucks for 120v LED bulbs? And take the risk of the higher current? 

5. Diito, but try for dimmable 12v LED's? Haven't found dimmable, be here something close: http://www.atlantalightbulbs.com/ec...506OPTILED 

BTW, I'm reviewing various 70-80W outdoor LED floods for "grounds lighting." Here's my favorite so far: http://1000bulbs.com/product/58605/LED-20P38830FL.html 

Over 10x more expensive, but I imagine I'll get that back with reduced energy costs. Any comments in that regard? 

Seems I have a long way to go in working this stuff out, but thanks so much for all your help, and best regards, 

===Cliffy


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## CliffyJ (Apr 29, 2009)

Well, those LED floods are a bust: at over 10x more expensive, and only 3x more efficient, it would take many (~17) years to pay off the investment for 10 1,000-lumen Par38's at max possible usage and $.1/kWh. Of course, there's certain inflation, but even so, I guess I need to stick with old fashioned outdoor incandescent floods for now. 

Just rambling here, but I wanted to post what I'd learned.

===Cliffy


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## krs (Feb 29, 2008)

Cliffy - 

Couple of comments re the LED floodlights; 

For one manufacturers always stretch the truth a bit when it comes to 110 volt LED light output especially when they list a "equivalent incandescent" wattage. 
The lamp your link points to claims Halogen equivalent of 80 watts but if you check the light output of halogen floodlights, you get about 1050 lumens with a 60 watt bulb, not an 80 watt bulb as they claim. 
So electric power saved is less than what you calculated. 
On the positive side - did you take into consideration the life span? Halogen floodlights are rated at around 2500 hours, the LED floodlight at 40 000 hours. This will definitely make the LED floodlight more economical in the long run if you use the light a lot. 

A sort of in the middle road approach would be to use a fluorescent floodlight - cost should be around $10 or less, life around 10 000 hours and light output well over 1000 lumens with a 23 watt light. 
Here is one example google gave me - there are lots of other choices. 
http://www.greenelectricalsupply.com/23-watt-par38-flood-cfl-dl.aspx 

If you need dimmable, look for that specifically - many fluorescents are not dimmable, for a warm white light you also want a color temperature of less than 3000 degrees K, 2850K is good. 

If you can replace incandescent floodlights with fluorescents at 1/4 the electric power you can save a lot of electricity.


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## CliffyJ (Apr 29, 2009)

Posted By krs on 23 Mar 2011 05:00 PM 
Cliffy - 

Couple of comments re the LED floodlights; 

For one manufacturers always stretch the truth a bit when it comes to 110 volt LED light output especially when they list a "equivalent incandescent" wattage. 
The lamp your link points to claims Halogen equivalent of 80 watts but if you check the light output of halogen floodlights, you get about 1050 lumens with a 60 watt bulb, not an 80 watt bulb as they claim. 
So electric power saved is less than what you calculated. 
On the positive side - did you take into consideration the life span? Halogen floodlights are rated at around 2500 hours, the LED floodlight at 40 000 hours. This will definitely make the LED floodlight more economical in the long run if you use the light a lot. 

A sort of in the middle road approach would be to use a fluorescent floodlight - cost should be around $10 or less, life around 10 000 hours and light output well over 1000 lumens with a 23 watt light. 
Here is one example google gave me - there are lots of other choices. 
http://www.greenelectricalsupply.com/23-watt-par38-flood-cfl-dl.aspx 

If you need dimmable, look for that specifically - many fluorescents are not dimmable, for a warm white light you also want a color temperature of less than 3000 degrees K, 2850K is good. 

If you can replace incandescent floodlights with fluorescents at 1/4 the electric power you can save a lot of electricity. 
Hey Knut!

BTW, sorry all for referring to the Malibu units as "dimmers," they're only transformers / programmable timers. Unfortunately, as Greg knows, they (according to Mal lit) can NOT be dimmed (though I'm sure Greg has found a workaround?). 

Anyway, I located a similar transformer for outdoor 12v lights, and they say it can be dimmed not only by standard dimmers, but by X-10 dimmers. Check this:

http://www.technomagnet.com/outdoor.htm

The 600W unit costs $100, which is a little cheaper than the equivelant Malibu, AND it's dimmable. Very cool.


But now to your points, Knut. Yeah, my spreadsheet does account for the items you mentioned, I was calculating based on lumens and life expectancy, not watt comparisons. But thanks for that additional background.

I really hosed up though was in factoring in the number of bulbs (10) in the cost, but not accounting for that in the total kWh! So... with the LED option, it's 1.7 years to pay off (again, assuming I'm outdoors every chance I get), NOT 17!









But thanks so much for that great suggestion on CFL's! Proves that I'm set in my ways, 'cause it didn't occur to me that there were much other than the squiggly indoor bulbs. And you're right, that's a wonderful alternative, because it works out that my using this approach would pay itself back in only 4 months (of heavy use, vs. typical incandescents)! And keep paying me back for... let's see... ~15years after paying for the difference, at $233/year (vs. incand.) electrical savings. Impressive!!

Here's the dimmable CFL I found:

http://1000bulbs.com/product/3951/FC23-93823ADIM.html

All this means that my flood circuit(s) can be dropped by about 2/3 of the loads I was using... wow!! Very exciting. So thank you Sir!!

Best regards,
===Cliffy


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## CliffyJ (Apr 29, 2009)

Well, I'm happy to say that my max loads are, like you guys indicated, much less than I'd originally calculated: ~26A for the main tier, and ~62A in the "if I live to be 120" plan. These loads are "open house, everything turned on" scenario, but that will of course be hugely rare. 

Thanks again Knut and Greg for all your help, 

Cliff


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## toddalin (Jan 4, 2008)

Posted By CliffyJ on 24 Mar 2011 03:40 PM 

Hey Knut!

BTW, sorry all for referring to the Malibu units as "dimmers," they're only transformers / programmable timers. Unfortunately, as Greg knows, they (according to Mal lit) can NOT be dimmed (though I'm sure Greg has found a workaround?). 


Best regards,
===Cliffy







I have dim and bright settings on my A/C lighting transformer.









I use a bridge rectifier to change the a/c to d/c and this provides the dim setting (~1/2 the a/c voltage). For the bright setting, a Big Azz Cap is switched in parallel with the load (about sq rt of 2 - 1.4 times the a/c). I use a 16.5 volt, 16.5 amp a/c source with a 12 amp circuit breaker (because I kept popping the 10 amp breakers) and get about 10 volts at the lights in the bright setting (over 22 volts in the garage) and 6 volts at the dim setting (lots of line loss due to a long wire run).


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## krs (Feb 29, 2008)

Posted By CliffyJ on 24 Mar 2011 03:40 PM 


Here's the dimmable CFL I found:

http://1000bulbs.com/product/3951/FC23-93823ADIM.html








Cliffy -

I don't know how important the initial cost is to you, but remember that dimmable flourescents are about three times the price of non-dimmable ones.
So make sure that's a "feature" you will use before you spend your money.

The other thing to check on flourescents is the minimum outside temperature they are rated for, incandescents and LED lights will light up at pretty much any outside temperature that we encounter in North America, flourescents won't.

The ones you picked show a minimum temperature of -4 F, here in Montreal Quebec where I am currently, we had the temperature drop to -40 Fahrenheit several years ago - these fluorescents wouldn't have worked outside.


I'm also not really clear which voltage you will be using outside for ground lighting - is it both 12 volts and 120 volts? We're sort of discussing both in the same paragraph. 


And another thing to remember if I haven't mentioned it. The X-10 system will only work on one phase of the power line unless you also buy a special bridging unit to pass the control signal between phases.
So you need to make sure the sender and receivers are on the same side of the power line.
In practice, I also found that the X-10 modules sometimes trigger erroneously especially if there is a lightning storm, so don't control anything that might become a problem if it turns on when nobody is home.
I only have lights connected to my X-10 modules, so that's OK, if they turn on by themselves, no harm done.

Knut


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## CliffyJ (Apr 29, 2009)

Cliffy -

I don't know how important the initial cost is to you, but remember that dimmable flourescents are about three times the price of non-dimmable ones.
So make sure that's a "feature" you will use before you spend your money.

The other thing to check on flourescents is the minimum outside temperature they are rated for, incandescents and LED lights will light up at pretty much any outside temperature that we encounter in North America, flourescents won't.

The ones you picked show a minimum temperature of -4 F, here in Montreal Quebec where I am currently, we had the temperature drop to -40 Fahrenheit several years ago - these fluorescents wouldn't have worked outside.


I'm also not really clear which voltage you will be using outside for ground lighting - is it both 12 volts and 120 volts? We're sort of discussing both in the same paragraph. 


And another thing to remember if I haven't mentioned it. The X-10 system will only work on one phase of the power line unless you also buy a special bridging unit to pass the control signal between phases.
So you need to make sure the sender and receivers are on the same side of the power line.
In practice, I also found that the X-10 modules sometimes trigger erroneously especially if there is a lightning storm, so don't control anything that might become a problem if it turns on when nobody is home.
I only have lights connected to my X-10 modules, so that's OK, if they turn on by themselves, no harm done.

Knut 


Thanks Knut, you raise more great points. Yes, I saw the price delta; and even the dimmable CFL's are impressively quite cost effective with the electric bill factored in. Very nice. Even so, I'll be using those only for area floods where I want to control the mood a little; and I'm planning on non-dimmables for "utility lighting" under the deck, where I'll need to store trains & etc. 

Yeah, I saw that temperature rating as I was poking around, and furtunately the bulb I cited has a -4F starting temp. But being a weenie, I'll not be messing around out there much if it gets below 20 or 30.









The 12v system is for a series of decorative fixtures up at my deck level, but the 120v are for general illumination of the layout. Also, I'm considering a simple / cheap 12v landscape path light system. Sorry for the confusion. Oh, and also the 12v system for model building illumination (probably using LED rope lights).

(I used to be into theatrical lighting, on an amateur basis, and I really love this stuff; but I guess it shows that I'm going overboard...) 

Great point about the same-phase thing, I didn't know that! I'll certainly have to watch out for that, and plan the circuits accordingly. Great point as well about the instability: I'll factor in as well.

One fly in the circuitry ointment I just discovered is that one should design a lighting circuit for max rating of fixtures, not intended wattage of bulb.







So... I guess I have to plan on 150W (or whatever) floods and 60 or 100 watt utility lights (or whatever) for circuit planning, instead of basing them on, say, 23w CFL floods. Which only makes sense, now that I think about it. So I've got to research fixtures now.... But still, with the CFL floods you brought up, the electrical savings will remain impressive.

Thanks again for taking the time to share your knowledge Knut,

===CLiffy


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## CliffyJ (Apr 29, 2009)

Another update, 

I'm totally striking out with my "utility" (under-deck) lighting ideas, using flood fixtures -- they're all rated at 150W, and I don't want to plan the circuit for that maximum. SO... I'm now thinking along the lines of a "construction light" string, e.g., 

http://www.amazon.com/Designers-Edg...G8MO/ref=sr_1_2?ie=UTF8&qid=1301090015&sr=8-2 

The logic here is that since the string plugs in, I don't have to size the circuit for the potential bulbs because they're not permanent. And I can use CFL's in those sockets. But, since these wouldn't be hard-wired fixtures, I'd need a GFCI on the plug. 

Thoughts Knut? 

===Cliffy


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## toddalin (Jan 4, 2008)

Posted By CliffyJ on 25 Mar 2011 04:39 PM 
Another update, 

I'm totally striking out with my "utility" (under-deck) lighting ideas, using flood fixtures -- they're all rated at 150W, and I don't want to plan the circuit for that maximum. SO... I'm now thinking along the lines of a "construction light" string, e.g., 

http://www.amazon.com/Designers-Edg...G8MO/ref=sr_1_2?ie=UTF8&qid=1301090015&sr=8-2 

The logic here is that since the string plugs in, I don't have to size the circuit for the potential bulbs because they're not permanent. And I can use CFL's in those sockets. But, since these wouldn't be hard-wired fixtures, I'd need a GFCI on the plug. 

Thoughts Knut? 

===Cliffy 






I use Harbor Freight's underwater, low voltage spot lights. They are waterproof (can be used underwater) and each include their own transformer (for a non-permanent installation), though I have mine wired to my "Malibu" system. BTW, they also offer various solar systems.


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## krs (Feb 29, 2008)

Posted By CliffyJ on 25 Mar 2011 03:07 PM 

One fly in the circuitry ointment I just discovered is that one should design a lighting circuit for max rating of fixtures, not intended wattage of bulb.







So... I guess I have to plan on 150W (or whatever) floods and 60 or 100 watt utility lights (or whatever) for circuit planning, instead of basing them on, say, 23w CFL floods. Which only makes sense, now that I think about it. So I've got to research fixtures now.... But still, with the CFL floods you brought up, the electrical savings will remain impressive.


Again - I'm not quite sure what you're getting at.
For any 115 volt circuit you need to size the gauge of wire to the fuse/breaker rating that protects that circuit.

So for a 15 amp fuse/breaker, the wire of that circuit has to be 14 AWG or larger. for a 20 amp fuse/breaker the wire gauge needs to be 12 AWG or larger.
That's all spelled out by the Electrical code.
It doesn't matter what the rating of the fixtures is.
The other constraints is of course the maximum power you expect to draw - you shouldn't exceed 80% of the theoretical maximum.
So for a 15 amp circuit your maximum design load should be 12 amps or less.
The fixture rating just determines the maximum wattage light you can install in that particular fixture.


Are you planning to do the 115 volt wiring yourself? 
Depending on your location, there may also be a local electrical code you need to comply to. Maybe run the cables in conduit, definitely use the special cable meant for in ground use, GFI's as you already mentioned.
12 volt wiring is much simpler - you don't need to have that wiring inspected, cable runs are determined by the power rating of the transformer and the total wattage of the lights on that run - possibly also the length of the run when you get into voltage drops if the run is long. But you don't have to worry about electrocuting anyone at that low voltage.


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## krs (Feb 29, 2008)

Posted By CliffyJ on 25 Mar 2011 04:39 PM 
Another update, 

I'm totally striking out with my "utility" (under-deck) lighting ideas, using flood fixtures -- they're all rated at 150W, and I don't want to plan the circuit for that maximum. SO... I'm now thinking along the lines of a "construction light" string, e.g., 

http://www.amazon.com/Designers-Edg...G8MO/ref=sr_1_2?ie=UTF8&qid=1301090015&sr=8-2 

The logic here is that since the string plugs in, I don't have to size the circuit for the potential bulbs because they're not permanent. And I can use CFL's in those sockets. But, since these wouldn't be hard-wired fixtures, I'd need a GFCI on the plug. 

Thoughts Knut? 

===Cliffy


As I said already - the rating of the fixtures just determines the maximum wattage of the light you can install in that fixture, nothing more.

Would you have a diagram of some sort that shows what you are trying to accomplish?
I still feel I'm poking around in the dark - pun intended.


That string you linked to - I would use something like that only for a very temporary lighting set up - say for a party, not for something that is intended to be permanent althugh some people do that.

Knut


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## CliffyJ (Apr 29, 2009)

OK, I'll be more specific. 

Example #1: Under-deck lights. I'd like ~10 outdoor fixtures under a narrow deck that wraps around the back of the house. This will be an area for train storage. 

Using 23w non-dimmable CFL's, that's 230w or 2.1A, and I can tie that into an existing dedicated 15A garage light circuit where there is 8.4A max hard-wired load. 

But if, as I've seen in a few electrical forums, I have to design for max watts per fixture (in case a later homeowner doesn't use CFL's), that's a problem. For example: 

"Now there are other factors that you need to make sure of like the rating of the fixtures. For example you could size for 75W bulbs but someone might decide to go to 100 W in the future." 
http://wiki.answers.com/Q/How_many_...mp_circuit

"Using the CFLs is a good idea, just still use the actual wattage rating of the fixture when figuring circuits." 
http://www.houserepairtalk.com/f9/n...aker-3771/ 

"Then you have to go by the can ratings not light bulbs, which are either 75 watts or 150 watts."
http://forum.doityourself.com/elect...rcuit.html


Now, regular, cheap, outdoor flood fixtures can handle a 150w bulb. So that would be 150W x 10, forcing me to either a dedicated circuit, or plug-in strings, or specialty (low volt, or LED) fixtures that have a low max wattage. Hence the construction string lights idea, because different rules apply for plug-in devices. But not being hard-wired, that approach would require a GFCI. 

Example #2: Area floods. Let's say I'd like to have 10 dimmable floods at 1,000 lumens. With 23w CFL's, we're again talking about 2.1A. Also, in the expansion plans where the layout wraps aorund into the front yard, I'd like another 10 floods. 

Again, this is all for purposes of determining total / ultimate circuits, and whether I should do a subpanel in the garage (where switches / dimmers / transformers / x-10 / DCC / GFCI / etc. stuff will be) this summer or just fish a couple of wires from spare breakers in the existing panel (and do the same whenever I need another circuit). 

Just like Example #1 though, if I plan the circuits for only 23w CFL bulbs, heck, I could put (15A * .8 * 110v) watts on a single circuit -- and that's 57 bulbs, or 57,000 lumens! Far more than I'd ever need. Further, I could use that same circuit for the under-deck lights. 

BUT, if I have to plan the circuits for max fixture rating, that would be a wopping (20 x 150w / 110v) = 27.3A, requiring 2 dedicated circuits, with not much elbow room. 

So... which is it? 
A. Can I do as you say, and ignore the max fixture rating? Or... 
B. Are the quotes (and I've seen several others like them) correct, forcing me to put in more circuits & watt capacity than the intended CFL or LED bulbs will ever require? 

I would love it if "A" was the answer!! It keeps circuits to a minimum, and appears to preclude the necessity of putting in a sub-panel (it would be pushing things otherwise). Which means more $ for track this year. 

Thanks again for taking the time for me on this Knut, 
Best regards, 

===Cliffy


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## CliffyJ (Apr 29, 2009)

Another update Knut, I just found a cheap, specifically-designed outdoor ceiling fixture for 23w (max) CFL's: 

http://www.homedepot.com/Outdoors-O...splay?langId=-1&storeId=10051&catalogId=10053 

So that would solve the under-deck lighting issue (could run them on the existing circuit I mentioned).


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## krs (Feb 29, 2008)

Posted By CliffyJ on 26 Mar 2011 08:07 AM 
Another update Knut, I just found a cheap, specifically-designed outdoor ceiling fixture for 23w (max) CFL's: 

http://www.homedepot.com/Outdoors-O...splay?langId=-1&storeId=10051&catalogId=10053 

So that would solve the under-deck lighting issue (could run them on the existing circuit I mentioned). 



Cliffy -

That fixture is not CSA listed, I assume it's also not UL listed (at least I didn't see anything that it is), so I would stay away from that.
If there is a fire or some problem due to this fixture your insurance company may not pay if you use non-listed devices on a 115 volt circuit.

As to the other questions - you are reading things into the answers that aren't there.
The rating of the fixture just limits the wattage of the bulb you can use in that fixture - it was nothing to do with total wattage of the circuit.
Look at something else - the wall outlets connected to a circuit.
Electrically a wall outlet is the same as a fixture, a place to pick up electric power for some electrical device.

A typical wall outlet usually has a 15 amp rating, that doesn't mean that you can only connect one 15 amp rated wall outlet to a 15 amp circuit. 

The number of wall outlets (or fixtures or a combination of the two) that you can connect to a circuit depends on the breaker rating/AWG (these two always go hand in hand and the expected use.
So for a bedroom circuit you could have a lot of wall outlets and fixtures since the amount of power used is relatively small - for a kitchen just the opposite, duplex wall outlets in the kitchen are often split with each half on a separate circuit since kitchen appliances tend to take a lot of power.


Cliffy - forget about the answers people provide in discussion forums and such. It's amazing the misconceptions people have when it comes to electricity.
Ha, ha - I guess that means mls as well.

In any case, either see if you can find the Electrical code on the web or at least some reputable site that covers the key points in the electrical code.
Here is one link I came across:


http://www.nojolt.com/residential_electrical_wiring_rough_in_guide.shtml#Branch-Circuits

Couple of excerps: 


[*]*As a rule of thumb you can put up to ten average light fixtures on a single circuit, unless this will add up to excessive wattage for the circuit (note, a ceiling fan and light kit qualify as one fixture). 

* [*]*Notable exceptions would be floodlights, which are high wattage fixtures. Four double bulb floodlights would pretty well fill up a circuit by themselves. 

* [*]*The actual rule for this is to not exceed 80% of the calculated wattage capacity of the circuit. 

* [*]*Wattage capacity of the circuit equals the amp rating of the breaker times the voltage (120), so for a typical 15 amp light circuit add up all of the maximum wattage's and make sure that they are less than 80% of 15x120 (1440 watts max).* [/list] *
* Notice it says "Rule of Thumb" because the electrical code doesn't actually specify the maximum number of light fixtures allowed; it certainly does not depend specifically on the rating of the light fixture.

If your still concerned about this call the office in your area that looks after the building code and talk to an inspector to see what he would allow. He is probably more interested that the wiring is done to code rather than counting light fixtures as long as you're within a reasonable number. Or use low voltage lighting under the deck and then you don't need to worry about any of this.

Knut 





:


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## krs (Feb 29, 2008)

Cliffy -

I would suggest you go and buy a small booklet that summarizes the key elements of the electrical code especially if you plan to do the wirung yourself.
But it's useful for planning purposes as well.

There are also some summaries on the net like this one:
http://www.mlec.com/Homeown.htm 
This is what the electrical code says about lighting branch circuits:

(e) General Lighting Branch Circuits - Shall be computed on a three watts per square foot basis. You may wire up to 600 square feet of living area on a 15 ampere branch circuit or up to 800 square feet on a 20-ampere circuit. These branch circuits may supply lighting outlets in all areas of the dwelling and receptacle outlets, other than those covered in (a) - (d) above.


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## CliffyJ (Apr 29, 2009)

Cliffy -

That fixture is not CSA listed, I assume it's also not UL listed (at least I didn't see anything that it is), so I would stay away from that.
If there is a fire or some problem due to this fixture your insurance company may not pay if you use non-listed devices on a 115 volt circuit.

As to the other questions - you are reading things into the answers that aren't there.
The rating of the fixture just limits the wattage of the bulb you can use in that fixture - it was nothing to do with total wattage of the circuit.
Look at something else - the wall outlets connected to a circuit.
Electrically a wall outlet is the same as a fixture, a place to pick up electric power for some electrical device.

A typical wall outlet usually has a 15 amp rating, that doesn't mean that you can only connect one 15 amp rated wall outlet to a 15 amp circuit. 

The number of wall outlets (or fixtures or a combination of the two) that you can connect to a circuit depends on the breaker rating/AWG (these two always go hand in hand and the expected use.
So for a bedroom circuit you could have a lot of wall outlets and fixtures since the amount of power used is relatively small - for a kitchen just the opposite, duplex wall outlets in the kitchen are often split with each half on a separate circuit since kitchen appliances tend to take a lot of power.


Cliffy - forget about the answers people provide in discussion forums and such. It's amazing the misconceptions people have when it comes to electricity.
Ha, ha - I guess that means mls as well.

In any case, either see if you can find the Electrical code on the web or at least some reputable site that covers the key points in the electrical code.
Here is one link I came across:


http://www.nojolt.com/residential_electrical_wiring_rough_in_guide.shtml#Branch-Circuits

Couple of excerps: 


[*]*As a rule of thumb you can put up to ten average light fixtures on a single circuit, unless this will add up to excessive wattage for the circuit (note, a ceiling fan and light kit qualify as one fixture). 

*[*]*Notable exceptions would be floodlights, which are high wattage fixtures. Four double bulb floodlights would pretty well fill up a circuit by themselves. 

*[*]*The actual rule for this is to not exceed 80% of the calculated wattage capacity of the circuit. 

*[*]*Wattage capacity of the circuit equals the amp rating of the breaker times the voltage (120), so for a typical 15 amp light circuit add up all of the maximum wattage's and make sure that they are less than 80% of 15x120 (1440 watts max).* [/list]*
* Notice it says "Rule of Thumb" because the electrical code doesn't actually specify the maximum number of light fixtures allowed; it certainly does not depend specifically on the rating of the light fixture.

If your still concerned about this call the office in your area that looks after the building code and talk to an inspector to see what he would allow. He is probably more interested that the wiring is done to code rather than counting light fixtures as long as you're within a reasonable number. Or use low voltage lighting under the deck and then you don't need to worry about any of this.

Knut 





:


All great points Knut, as usual. I'll hit on a few.

Good catch on the UL / insurance thing (!) for that particular fixture. Couldn't locate the manufacturer either, which is suspicious. 

In all my searching on this subject, yes, the phrase "rule of thumb" keeps popping up, which underscores the NEC expects some wisdom to be exercised, and can't legislate all circuit / load permutations, etc.

However, I want to be clear on what you're saying, and not saying. 

You've been underscoring that circuits are sized per total bulb wattages expected, and not what the total wattage capacity of the installed light fixtures are. This is the crux of my recent questions to you; is that a fair summary? I hope I'm understanding you properly, and I sure don't mean to put words in your mouth. 

Regardless, you've seen the quotes I've cited, to the contrary of that position.

However, and to your point, here's a fictituous example of "rule of thumb" and "wisdom" in regards to applying the NEC:

Let's say I have a circuit sized for 10 fixtures, each of them being simple, bare-bulb, porcelain types, in my attic (let's say it's a big attic). I'm only planning on using 100w bulbs in each; and why do more? But though it would be up to snuff code-wise, and the inspector would bless it, I could easily screw in 250w floods after the inspector left. And blow the breaker. Which is what it's there for.

So, perhaps my situation with outdoor flood fixtures, on a circuit designed for only 23w bulbs, is analagous. Not sure; and your idea of getting an inspector out the the site is an excellent one. But even if he was OK with it, it would probably be a good idea to modify the fixture's internal label from "150w max" to "23w CFL max", or something like that, just in case.

Are we converging here?

Thank you sir,
===Cliffy


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## CliffyJ (Apr 29, 2009)

Posted By krs on 26 Mar 2011 10:05 AM 
Cliffy -

I would suggest you go and buy a small booklet that summarizes the key elements of the electrical code especially if you plan to do the wirung yourself.
But it's useful for planning purposes as well.

There are also some summaries on the net like this one:
http://www.mlec.com/Homeown.htm 
This is what the electrical code says about lighting branch circuits:

(e) General Lighting Branch Circuits - Shall be computed on a three watts per square foot basis. You may wire up to 600 square feet of living area on a 15 ampere branch circuit or up to 800 square feet on a 20-ampere circuit. These branch circuits may supply lighting outlets in all areas of the dwelling and receptacle outlets, other than those covered in (a) - (d) above. 
Thanks very much for that link to the summary Knut.

Indeed, I've seen that NEC paragraph several times in my searches, but it applies to indoor systems, not outdoor lighting. You can have a single outdoor flood at 60w; but that doesn't mean you have to sive that circuit for 3w/sf for the total acreage of your property.









And thanks for hanging with me on this stuff! 

Everybody else... sorry for this thread being un-trainly, but I'll just plead that I'm driven into these territories of learning ONLY because of the planned layout.









===Cliffy


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## CliffyJ (Apr 29, 2009)

Yet another update... 

Found this "sister product" of that outdoor ceiling light by the same mfgr, which is stated to be UL & CSA listed: 

http://www.mylightingshop.com/shop/...tdoor-ceiling-light-Energy-Star-398p20005.htm 

Note to self: I'll have to drop by Home Depot and see if that other one has the same rating (the HD database isn't always up to date, I've found).


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## krs (Feb 29, 2008)

Posted By CliffyJ on 26 Mar 2011 01:21 PM 

In all my searching on this subject, yes, the phrase "rule of thumb" keeps popping up, which underscores the NEC expects some wisdom to be exercised, and can't legislate all circuit / load permutations, etc.

However, I want to be clear on what you're saying, and not saying. 

You've been underscoring that circuits are sized per total bulb wattages expected, and not what the total wattage capacity of the installed light fixtures are. This is the crux of my recent questions to you; is that a fair summary? I hope I'm understanding you properly, and I sure don't mean to put words in your mouth. 

Regardless, you've seen the quotes I've cited, to the contrary of that position.

However, and to your point, here's a fictituous example of "rule of thumb" and "wisdom" in regards to applying the NEC:

Let's say I have a circuit sized for 10 fixtures, each of them being simple, bare-bulb, porcelain types, in my attic (let's say it's a big attic). I'm only planning on using 100w bulbs in each; and why do more? But though it would be up to snuff code-wise, and the inspector would bless it, I could easily screw in 250w floods after the inspector left. And blow the breaker. Which is what it's there for.

So, perhaps my situation with outdoor flood fixtures, on a circuit designed for only 23w bulbs, is analagous. Not sure; and your idea of getting an inspector out the the site is an excellent one. But even if he was OK with it, it would probably be a good idea to modify the fixture's internal label from "150w max" to "23w CFL max", or something like that, just in case.

Are we converging here?



Cliffy -

If there are hard requirements in the NEC the code will spell them out as such. 
I'm not even sure that the NEC itself actually contains any "rule of rhumbs" since they wouldn't be enforcable.

If the "rule of thumb" is say 10 fixtures per 15 amp circuit and you end up wiring eleven to one circuit, the inspector couldn't say - sorry, can't approve the wiring, not to code. Makes a "rule of thumb" useless from a code point of view.

When you read through the comments in the links you posted you will find some correct information and some wrong information - sometimes the wrong information gets corrected, sometimes not.
When a licensed electrical contractor says he uses the ratings of the fixtures to determine how many are connected to one circuit, that's his choice - he can make up the rules for his staff as long as they don't conflict with the NEC and that is all he is doing.
As I metioned earlier, strangely enough nobody applies their "rule of thumb" about the rating of fixtures to determine allowable numbers on one circuit to the number of outlets that are allowed on a single run. Wonder why not - oh, maybe because this would only allow one outlet per 15 amp circuit.


And yes - you understand correctly:
_You've been underscoring that circuits are sized per total bulb wattages expected, and not what the total wattage capacity of the installed light fixtures are._

In fact - I just looked at the house I'm at - four bedrooms, each bedroom has 5 wall fixtures each with an individual switch. fixtures are rated at 150 watts each. all on the same 15 amp circuit. 

That exceeds the "rule of thumb" some contractors use, the one who wired this house obviously had a different 'rule of thumb'
Lightbulbs are typically 23 watt flourescents, so the actual wattage used if one or two lights are on in each bedroom at the same time is only about 200 watts on a 15 amp circuit.

Even if all the lights were 150 watt bulbs, since only two lights per bedroom would be on the total wattage is still below the maximum for that circuit.
No residential wiring is laid out to allow maximum current to be drawn from any fixture and outlet at the same time.


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## krs (Feb 29, 2008)

Posted By CliffyJ on 26 Mar 2011 01:31 PM 
Posted By krs on 26 Mar 2011 10:05 AM 


This is what the electrical code says about lighting branch circuits:

(e) General Lighting Branch Circuits - Shall be computed on a three watts per square foot basis. You may wire up to 600 square feet of living area on a 15 ampere branch circuit or up to 800 square feet on a 20-ampere circuit. These branch circuits may supply lighting outlets in all areas of the dwelling and receptacle outlets, other than those covered in (a) - (d) above. 
Thanks very much for that link to the summary Knut.

Indeed, I've seen that NEC paragraph several times in my searches, but it applies to indoor systems, not outdoor lighting. You can have a single outdoor flood at 60w; but that doesn't mean you have to sive that circuit for 3w/sf for the total acreage of your property.











Oh boy - just lost a long reply with this forum software.

Anyway - briefly -

Reason I posted this:
(e) General Lighting Branch Circuits - Shall be computed on a three watts per square foot basis. You may wire up to 600 square feet of living area on a 15 ampere branch circuit or up to 800 square feet on a 20-ampere circuit. These branch circuits may supply lighting outlets in all areas of the dwelling and receptacle outlets, other than those covered in (a) - (d) above. 

is because it reinforces my point/
At 3 watts per square foot and a 600 sqare foot area, a total of 1800 watts are allowed per 15 amp circuit. Nothing there about the number of fixtures or outlets - period.


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## krs (Feb 29, 2008)

Oh, and in general. 
Re-evaluate if you really need 10 floodlights under the deck where you store your trains. 
Get floodlights with a wide beam and I would think 4 or max 6 are plenty. 
Just try it out at night with one on a temporary basis using an outdoor extension cord - I use four 150 watt halogen floodlights o light up a very large back yard.


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## CliffyJ (Apr 29, 2009)

All great points, Knut. Sorry you lost that longer post; man, I hate it when that happens!

BTW, I was sort of pulling your leg, on my "total acreage of your property" comments  

So I think we're in violent agreement here, and I'm very much relieved. Thanks again for taking the time. 

That's a great idea about putting up some temp fixtures. Should do that with both the under-deck and area flood stuff! 

What did you think about that second CFL fixture I linked to? Same mfgr, but UL/CSA listed, and it has a guard. Which is probably a good thing, since there is a very low ceiling beneath this deck.

Best regards,

===Cliffy


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## CliffyJ (Apr 29, 2009)

I use Harbor Freight's underwater, low voltage spot lights. They are waterproof (can be used underwater) and each include their own transformer (for a non-permanent installation), though I have mine wired to my "Malibu" system. BTW, they also offer various solar systems.

Hey Todd, sorry for not replying earlier; but thanks for the idea. I checked them out, and was wondering if you'd seen anything in the instructions about requiring water submersion for cooling purposes? 

I'll probably go with the 23 watter CFL's I mentioned prior, they have good coverage for the storage area I'm planning on. But I'll sure keep this very cool product in mind for other applications.

Thanks buddy,
===Cliffy


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## krs (Feb 29, 2008)

Posted By CliffyJ on 27 Mar 2011 10:08 AM 


What did you think about that second CFL fixture I linked to? Same mfgr, but UL/CSA listed, and it has a guard. Which is probably a good thing, since there is a very low ceiling beneath this deck.







Looks OK to me.
I just find it a bit expensive for a fixture that's out of sight.
There are very similar fixtures for 12 volt lighting where you get a set of eight for not much more than $40.-

And if you have a problem with headroom, how about mounting the lights (different type maybe) on the vertical surface of a joist or post.
I like the simple floodlight mountings that swivel - that way you can adjust them and shine the light whereever you need it.
Again - best to try things out on a temporary basis before you spend your money.

Knut


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## CliffyJ (Apr 29, 2009)

Looks OK to me.
I just find it a bit expensive for a fixture that's out of sight.
There are very similar fixtures for 12 volt lighting where you get a set of eight for not much more than $40.-

And if you have a problem with headroom, how about mounting the lights (different type maybe) on the vertical surface of a joist or post.
I like the simple floodlight mountings that swivel - that way you can adjust them and shine the light whereever you need it.
Again - best to try things out on a temporary basis before you spend your money.

Knut 

Similar fixtures, in 12V, that cheap? Can you give me additional info?


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## krs (Feb 29, 2008)

That fixture was part of a set that also included a transformer and low voltage cabling. 
I saw it at a local store last fall, they had a round fixture pretty much identical to the one in your picture and also an oval one in the same design except for the overall shape. 
But the fixture was all black plastic and used these 12 volt Garden lighting bulbs. 

I find lately there seems to be a trend towards solar powered LED lights for the garden so the choices of low voltage fixtures have become much less. 
I think now, at the beginning of spring, you can probably find a good selection of low voltage light kits at good prices. If you get those for some of your lighting and they are relatively cheap, I would suggest you get an extra box as "spares". If any of them break or get damaged, you have a replacement since the chances of finding an exact match even a year down the road will be pretty much zero.


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## CliffyJ (Apr 29, 2009)

Excellent Knut, I'll be on the lookout for those guarded fixtures. And yes, it's indeed the time of year for selection. Good point on getting spares, I like that. 

Here's another one for you, and perhaps Greg (or anyone else, if so moved). 

Let's say I have a circuit dedicated to low voltage lighting, and the cable goes to the garage, through some X-10 (or whatever) switches, and directly to the transformers right there. 

Now, the transformers I'm looking at are hard-wired; and as far as I'm able to to find on the subject, one doesn't need GFCI's for hard-wired lighting. But should I put in GFCI's just for safety's sake (say, with a damp garage floor)? 

Or, since the loads are all downstream of the transformer (and this is the main question), will the GFCI do much good at all? 

For that matter, to what extent does one need to ground-wire 12v outdoor devices (e.g., store-bought or home-grown fixtures, special effects lights/motors, etc.)? 

And again, if there's a fault in the ground on the 12v side (if needed), will the 110 GFCI play any safety role? 

The reason I'm asking is that I'm currently planning on using GFCI's on the feeds to all such low-voltage circuits, and am wondering if certain of them are pointless. 

Thanks very much Knut (and anyone else inclined to opine), 

===Cliffy


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## CliffyJ (Apr 29, 2009)

Another update, to show how my power "center" design is trending.










The items in solid red are what I wish to install this year. Those in dashed-white are for, God willing, future stuff.

The small rack of rectangles to the right are the interface devices, e.g., dimmers and switches and GFCI's. Connective wiring to/from these devices would be behind a (hinged) panel, with adequate service loops to the incoming and outgoing cables.

This is in a garage; and after serious storms, the floor may become damp.

Referring to that device rack on the right, there are 5 dedicated ciruits involved, one each for (right to left) track (dcc) power, signal/FX power, model lighting, path lighting and area lighting.

The next thing I'm interested in looking at is whether to slice the circuits the other way, i.e., one dedicated circuit per "tier", as opposed to function.

Well, that's about it.

===CLiffy


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## krs (Feb 29, 2008)

Cliffy - 

There is no GFI required for any 12 volt circuits. The voltage is too low to cause a problem if you touch it even on a damp floor. 
GFI protection for a hard-wired feed to a transformer (for the 12 volt circuits) doesn't do anything provided the wiring is protected i deally in a conduit so one can't drive a nail through it accidentally. 
However, any outlet in the garage or outside must be GFI protected - not only required by law but also cheap insurance against electrocuting yourself. 
You should test the GFI a few times a year to make sure it's fully functional. 

On your last post re "slicing the circuits" differently. I always try to run circuits in a way so that I don't loose all power in an area if a breaker trips. 
Nothing says you have to run the circuits per "tier" or per "function" - just look at the total power requirements and what happens if each circuit looses power due to a fault. You don't want to be crawling around under the deck, have the breaker trip and then sit in the dark if you can avoid that.


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## CliffyJ (Apr 29, 2009)

Posted By krs on 31 Mar 2011 02:02 PM 
Cliffy - 

There is no GFI required for any 12 volt circuits. The voltage is too low to cause a problem if you touch it even on a damp floor. 
GFI protection for a hard-wired feed to a transformer (for the 12 volt circuits) doesn't do anything provided the wiring is protected i deally in a conduit so one can't drive a nail through it accidentally. 
However, any outlet in the garage or outside must be GFI protected - not only required by law but also cheap insurance against electrocuting yourself. 
You should test the GFI a few times a year to make sure it's fully functional. 

On your last post re "slicing the circuits" differently. I always try to run circuits in a way so that I don't loose all power in an area if a breaker trips. 
Nothing says you have to run the circuits per "tier" or per "function" - just look at the total power requirements and what happens if each circuit looses power due to a fault. You don't want to be crawling around under the deck, have the breaker trip and then sit in the dark if you can avoid that. That's great info Knut. 

You confirm what I was suspecting about the transformers, especially since they don't plug in. Thanks.

Good points about the "slicing" thing. I did a what-if spreadsheet, to see how things added up for a "per tier" approach. Put differently, I wanted to see if I might only run a single 20A circuit for everything I'm needing in the next 3 or 4 years (the first phase or 'tier' of the layout). Turns out I can (thanks to all your help in finding the right lighting devices). 

Still working out the ramifications, but if I did that initial single circuit approach, things would get mighty simple. And when (and if) a new chunk of layout is added down the road, only one corresponding new circuit would be as well. 

The alternative would be the "function-based" approach, where I'd need to run all the circuits up front, and not really know if they would be fully utilized. If I do a subpanel, that's no problem, but I still need to get my contractor-friend out here to discuss that option / cost.

I like the point you bring up, re. bringing everything down if 1 circuit trips. 

Thanks again for your help,

===Cliffy


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## CliffyJ (Apr 29, 2009)

Knut, 

I've run a quick comparative analysis between the two approaches (circuits designed on function, vs. layout section), and I want to say thanks again for raising that point of single-circuit vulnerability. It's become a huge factor, now that I see what's affected by what, and what the workarounds might be, under circuit-tripping circumstances. Great catch. It's looking like the per-layout-section approach is winning hands down. 

===Cliffy


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