# New 24v power source Basic Q? plus the green ground.



## Totalwrecker (Feb 26, 2009)

*A couple of weeks ago we were having a discussion on power supplies and George suggested a power unit from MPJA. I ordered one and it doesn't have an attached power cord. Hooking one up would be no problem if I knew which wire goes where. I know the ground symbol, but which wire goes to L(oad) and N(eutral). I haven't picked up the cord yet, but I'd guess the wires will be black and white, plus the green ground.
Sorry to bother you with such a basic question, but we all start somewhere.

John

Sorry tried to edit subject line... no go
*


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## Stan Cedarleaf (Jan 2, 2008)

Hi John.... Does this help?


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## George Schreyer (Jan 16, 2009)

Some cords are black (netural) white (load or hot) and green (ground)


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## lownote (Jan 3, 2008)

That's what I remember when I did mine--black neutral and white to plus


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## Stan Cedarleaf (Jan 2, 2008)

Yup, certainly understand.... this is the way it came from the distributor....


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## Greg Elmassian (Jan 3, 2008)

Mike and George, just to make sure others do not misunderstand, Stan has the "correct wiring" per the common wiring code for houses, in your house white is neutral and actually grounded in your breaker box, and black is "hot". 

(George, I know you are warning about an incorrectly coded cord; Mike, you have it backwards) 

 http://www.make-my-own-house.com/home-electrical-wiring.html

If you find power cords miswired, I would throw them away and get one wired properly, even though it's not a problem for the power supply itself. Cords are cheap. 

Regards, Greg


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## Totalwrecker (Feb 26, 2009)

It does .... until there were so many wires coming off the hot side. Is every pair of terminals 24/ 12.5 amps or a fraction of the amps? Would you power 3 seperate loops that way?

Will it negatively affect the power supply if the wires are backwards? IE bad cord...

I see your's has an on/off switch... hmmmm good idea.

Sorry about my delay in thanking all of you, had to finish a roofing job before the triple digit heat gets here.

Thanks 
John


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## Greg Elmassian (Jan 3, 2008)

All connected together, mostly for convenience... If you were drawing max load, you could double up, but no reason really. You have 3 pairs of "tie points" for power, just makes it easier. 

No effect on the power supply to reverse hot and neutral... internally the hot and neutral should have equal insulation to the chassis. 


Regards, Greg


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## George Schreyer (Jan 16, 2009)

There are multiple outputs so that multiple wires can be connected to share the load so that one terminal doesn't have to take it all. You COULD take the output from just one terminal, but the regulation would not be as good and that terminal may overheat.


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## RioShay (Feb 26, 2009)

Hey guys, i just had the worst sinking feeling in my stomach after almost being able to figure out what everybodys saying. we 're expecting our MW S320-24, as shown, tomorrow, and we thought it was a simple hook up, but we're a little confused now. on the input, wire according to STAN's diagram ? WHITE to L , BLACK to N, GREEN to GRND?, ...and on the output, do the multi outputs , according to GEORGE, all get tied into the track ,for better voltage regulation, at the same place?...our SS track is up and runable with our RC train, ...but i feel kinda unsure now, i hope i don't start a forest fire or burn the house down!.. help!


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## George Schreyer (Jan 16, 2009)

The green wire goes to earth ground 
The white wire is neutral 
The black wire is hot 

you can use only one pair of output terminals, but it is better to use more pairs.


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## RioShay (Feb 26, 2009)

THANKS GEORGE, we really appreciate your patience and great tips n info, here and your tipsite. input is very clear now, and on the output, one pair would power up our controller, but more pairs are better? where would they go? to our aristo ultima 10amp controller also?. we're kinda in the dark now without the boxes right in front of us to actually see all the conections, but we hope to have everything in hand by the weekend, again , thank you very much for your info n patience, we're greatful for the "beginner's section", and we're having alotta fun building, running, and planning our garden railroad, thanks to MLS


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## Totalwrecker (Feb 26, 2009)

Thanks everybody for all the help. 

OK I'm ready to take the quiz; 

Outputs; all 24 volts, the more amps drawn the more outputs used. 

I doubt if I'll ever draw morre than 5 amps (2 trains) So in theory one pair should be fine, but when I have a massive derailment and track shorts, I'll need more output lines to ensure a complete melt down? lol 

I'm thinking that those with a high draw, use more wires to keep the heat down for safety reasons at the terminals because a thicker wire should handle the amps. 

Do these units have circuit breakers or should I consider line fuses? Or is it necessary? 

My application is constant 24v track power and floating batteries that charge off the rails through IPTrains' electronics, w/Del's Railboss as my controller.


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## lownote (Jan 3, 2008)

That IPTrains "floating battery" idea is very cool. I wonder how well it works? It'd be an easy way to add a reverse loop without going to DCC, and it would smooth out operation on days when the track is dirty. Hmmmm....


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## Schlosser (Jan 2, 2008)

Perhaps some history would help in remembering which is the hot wire. 

In the beginning, only black wire was manufactured (probably hard to make white insulation), and it was a single wire. And also in the beginning, electricity was used mainly for lightis in a house; receptacles were in the future ('socket powered' radios replaced radios with batteries, but you powered them from a lighting fixture thus the 'socket powered' nomenclature). 

The switch for the light was placed in the hot lead so that you wouldn't fry yourself changing a light bulb. The electrician had a small can of white lead paint that he used to mark the black wire to indicate that it was hot, at the switch and at the socket for the bulb. 

The single wire ran through a porcelain tube in the 2x4s framing the house. And often the wire to and from the light did not run beside each other, causing a 'loop'. Codes were written outlawing the loops. Were they really a health risk? 

And of course, white wire replaced the white lead paint. 

But this was before my time, really. 

Art 

Edit: Good Gollies, Gertrude, what can I say? Maybe the politicians: "I DISREMEMBERED???"

Can't blame my oldest brother who told me the tale as he's not been with us now for some 20 years. I am at fault, so *I *will have to go stand in the corner.

ATTENTION EVERYBODY! DISREGARD WHAT I FIRST POSTED ABOVE! UNLESS YOU PAINT THE COMMON WIRE INSTEAD OF THE HOT WIRE (but leave the switch in the hot lead)!

And what's worse, I know better. Serves me right for using daylight hours and hurrying when posting. 

I've been in houses that had both red and black hot wires, opposite phases for a 240v circuit so there's 240 volts between them for dryers, stoves, etc. So it's natural to find both in the kitchen - but in the same duplex outlet box, one wired to the top outlet - and the other phase wired to the bottom outlet!! Sounds like a potential safety hazard to me.

Always amazed that radio and TVs, being electrical, had the black wire as 'ground' and used red for B+; guess they thought red looked hotter than black or white.

Mea Culpa, Art


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## Greg Elmassian (Jan 3, 2008)

Interesting, but that story seems to indicate that white indicates hot, which is not how it is now, black is hot, and white is neutral (effectively ground). 

Regards, Greg


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## George Schreyer (Jan 16, 2009)

In house wiring, black is one side of the 220 coming in, red on the other side, white goes back to the center tap on the pole transformer. 

The floating battery concept is not at all new. I first use it trying to stabilize the DC power to a DCC decoder. Basically the resistor limits the charge current going into the battery. The parallel diode provides a low voltage drop path for current leaving the battery. Lenz does pretty much the same thing on their newest DCC decoders but they use supercapacitors. 

The guy at IPTrains says that the first time he had seen the technique was on my web site, he said that I probably "own" the IP for it but I doubt it. It is too obvious. The system was ok for charging a capacitor but I never trusted it for charging a battery as the charge rate could become poorly controlled. His system relies on a track voltage (DC or DCC) of 22 to 24 volts. Below 22 and the charge rate is too low, above 24 and the charge rate is too high. However, after playing with his system a lot, it seems to work well.


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## Semper Vaporo (Jan 2, 2008)

Sorry, Art, but you have given the indication that the white wire is the hot lead and that is not true.

Assuming that your house is wired according to U.S. electrical code and assuming that you have a 3 wire system.

One wire will be BLACK and that is the HOT wire.

One wire will be WHITE and that is the NEUTRAL wire.

One wire will be BARE (or wrapped in paper) and that is the GROUND wire.

If you remove the cover of your fuse (or circuit breaker) box where the main power comes into your house (BE VERY CAREFUL IF YOU DO THIS! DEADLY VOLTAGES ARE PRESENT ON UNINSULATED/EXPOSED BINDING POSTS! If you don't touch nuttin' you are safe, but be carefully with the cover as it is big, unwieldy and metal and could touch something that could KILL YOU!):

You will find the BLACK wire from each circuit of your house connected to the output side of one fuse/circuit breaker for that circuit.

You will also find WHITE and BARE wires connected to long copper buss bars. YES, they are connected together at the power panel and electrically are considered the same wire at the socket in your living room. The WHITE and BARE wires are a redundancy safety factor. If one happens to break the other will take the electrical current back to the power panel and back to the power supply from the electrical company. The bare wire is also often connected to the metal chassis of the appliance that is plugged into the socket so when you are touching the chassis (like the body of a metal cased electric drill!) you have your hands on the ground side of the electrical circuit!

Your power panel SHOULD have another connection to those buss bars. That connection is to either the cold water pipe in your house or a copper (or copper clad steel/iron) bar that is poked into the ground near the panel.

The term "GROUND" is exactly what it means... earth, dirt, ol' mother earth, what your house is sitting in, what you get embedded in your knee when you trip over a root and fall down. The power system of the generators at the power generating plant has one wire connected to the GROUND too. Everything sitting on the ground is at, what is called, "Ground potential".

A previous owner of my house built a deck on the back, but they did not raise the electrical wires from the house to the garage higher to make it more difficult to reach them from the ground (a violation of electrical building codes), so I decided to move them higher on the house and garage. At the garage I noted that they also did not run the wires in conduits or use electrical boxes to cover the connections to the various wires to lights and outlets. I also noted that at one point they had connected a BLACK Wire to a BARE wire and at the socket that bare ware was properly connected to the 3 prong socket. It was wired such that one could plug in a two wire appliance and it would work (and was safe if you didn't touch the metal box), but if you plugged in a three wire appliance where the 3rd prong was connected to the metal case of the appliance the case would be "HOT" and DEADLY!

No matter what, KNOW what wire is which when working around house power! Use a Volt meter to verify that voltage is NOT present when you are messing with house power.


Because this is so important, I just went down in the dungeon and took the cover off my electrical panel and verified the colors. I also noted that I have some RED wires and they are just like the BLACK ones.


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## George Schreyer (Jan 16, 2009)

Red and black may look the same on a voltmeter, but there is 220 volts across them. 

Hopefully, the loads on the red and black wires are farily well balanced so that there is little current flowing in the neutral wire leading back to the transformer. The neutral wire is ALSO grounded to earth in your breaker box (the English call it "earth" anyway). The green wire (or bare) wire is also connected to earth in the box. 

I had a case where a bundle of white wires under a wire nut became poorly connected and one circuit of my house was returned to ground only via other circuits. There was a large load imbalance and therefore a large voltage imbalance. Some loads only had 50 volts, some had 180 volts. I thought that those outdoor halogens were kinda bright....


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## Semper Vaporo (Jan 2, 2008)

Posted By George Schreyer on 06/05/2009 11:37 AM
Red and black may look the same on a voltmeter, but there is 220 volts across them. 

Hopefully, the loads on the red and black wires are farily well balanced so that there is little current flowing in the neutral wire leading back to the transformer. The neutral wire is ALSO grounded to earth in your breaker box (the English call it "earth" anyway). The green wire (or bare) wire is also connected to earth in the box. 

I had a case where a bundle of white wires under a wire nut became poorly connected and one circuit of my house was returned to ground only via other circuits. There was a large load imbalance and therefore a large voltage imbalance. Some loads only had 50 volts, some had 180 volts. I thought that those outdoor halogens were kinda bright....


Yes, there SHOULD be 240 Volts between RED wires or a red and black at the same socket or appliance, but that don't mean MY house was wired by anyone that knew that! Remember they also wired HOT to Bare in the garage!

I have black wires from each side of the 120/240 setup as well as red wires. Some of the red wires go to the same appliance (240 Volt operation of the stove and air conditioner). The rest just go someplace where the previous owners needed to run some 120 Volt power and apparently some red wire was available! 

But, even as red wires they are still each just 120 Volts from Neutral just like the black wires on that side of the incoming house power. Some of the black wires, being connected to one side of the house power are 240 Volts from other black wires connected to the other side of the house power. 

What you say about balancing the load across the two halves of the 240 Volt lines is true. I have seen some really odd things in a house where one side of the house power had all the lighting and the other side was just the sockets that appliances are plugged into. Poor or bad connections here and there can make for some really odd Voltage measurments! Lights being turned on or off would affect fan speeds drastically and could burn out power supplies in radios and TVs due to home induced "brown-outs".


To bring this to the OP's original question... if the power supply is properly built then NEITHER of the TWO POWER connections will be tied to the metal chassis of the power supply, thus it may not matter which wire goes to which connection. Assuming there is a third connection for the bare/green wire then if you wire it up "wrong" (i.e.: connect the black to the power supply Neutral and white to the power supply Load In) then IF the chassis IS connected to the ground side of the two wires then as soon as you plug it in the fuse will blow in the house ciruit and you will know it is wrong. If the fuse does not blow then either the fuse is shorted internally (or has a penny behind it!) or the "ground" side of the two wires is not connected to the chassis.

Also, to carry this a bit farther about U.S. only wiring... if you have a plug that does not have the third round pin for the safety ground, then one of the blades of the two will be slightly wider than the other. That one is the Neutral connection. The narrower one is the HOT side. This is a kind of safety thing... the bigger connection, that thus being bigger may be easier to touch, is ground and thus safe. The smaller one, thus maybe a teeny tiny bit harder to touch, is the hot/unsafe side.

Also, People used to install the three prong outlets so that they looked like a "face", with the round hole at the bottom (like a mouth) and the two blade slots at the top (looks like two eyes). Today that is considered less safe (but not illegal). The theory is that if a plug is slightly out of the socket and something drops on it, if the ground prong (the round one) is on top then what drops on it will be deflected away from the hot wire below it. If installed the other way then something dropped on it might contact the hot wire and cause a problem. 

It is not illegal (at present) because there are so many appliances where the power cord is arranged such as to have the cord hang down nicely against the wall with the ground on the lower (cord side) of the plug. Some appliance cords now have the ground pin away from the cord so the cord will still hang down nicely with the socket installed the other way. You are encouraged to replace cords with the newer style (pin away from the cord) and to turn your outlets to accomodate them. Of course, most cords have the pins in line with the cord so that the cord sticks out from the wall and presents a tripping hazard or keeps you from moving a table or chair close to the wall, and also makes the plug droop due to gravity and get unplugged by just hanging there.


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## George Schreyer (Jan 16, 2009)

The wide neutral prong is wider so that it won't fit into the hot side making it impossible to get it reversed. HOWEVER, older outlets didn't have a wide slot and some folks, instead of upgrading the outlets, simply trim off the wide prong. If an appliance is built right, it won't be immediately dangerous, but a light bulb may have the screw base then connected to the hot side so as you unscrew a bulb, the now hot, screw base becomes exposed and can be touched.


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## Totalwrecker (Feb 26, 2009)

Thanks Guys, 
This has been a great primer! 

Sorry I didn't get back sooner, I had a MacAfee melt down that kicked me off IE. New brand AV disc installed, swept and cleaned. 

Am back to buttoning up the loco, nice weather this weekend. 

Thanks Again for sharing your knowledge, 

John


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## SteveC (Jan 2, 2008)

Posted By Greg Elmassian on 06/04/2009 4:47 PM
_{snip...}_ No effect on the power supply to reverse hot and neutral... internally the hot and neutral should have equal insulation to the chassis. {snip...}[/i]
Greg, et al

While what you've stated is true in regards to the power supply working properly, regardless of which way one hooks up the input AC.

However, it is a very poor idea and dangerous to get in the habit of deviating from the proper way to wire the AC input to equipment as designed...
[*] Black wire connected to terminal labeled/intended for L (line, load, hot).
[*] White wire connected to terminal labeled/intended for N (neutral)
[/list] Otherwise, if wired backward...
[*] Black wire connected to terminal labeled/intended for N (neutral).
[*] White wire connected to terminal labeled/intended for L (line/load/hot).
[/list] While the equipment will likely still operate properly. With the equipment's power switch placed in the OFF position, instead of the electrical potential only being present between the input side of the power switch, back to the line side of the receptacle where the equipment's power cord is plugged in. This will be the only place that the electrical potential won't be present in the equipment. Thus creating a dangerous condition for anyone working on that piece of equipment.

Additionally, while it's very rare that the average individual using the electrical receptacles in their home ever check to see if these receptacles are wired and functioning correctly, they should. All electricians aren't as careful as they should be, and things do go bad over time. There are relatively inexpensive testers available that most anyone can learn to use.


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