# Bus bar



## CraigW (Mar 9, 2012)

My start on a garden railroad has about 125 ft of track. Plan to run a continuous bus bar from a 10 Amp power supply with 10 THHN. Road bed is supported by an HDPE system as depicted in Garden RR magazine. Track is all LGB brass with split jaw fasteners at every track junction. Two R1 curves and a free form using R3 curves. Straight sections are mostly four ft LGB track sections. How far apart should I space power taps from the bus to the track?


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## ralphbrades (Jan 3, 2008)

What you have to remember is that your brass rail is a better "buss bar" than your connecting cable... If you follow the standard G1MRA recommendations for track electrification then you have a small "tap wire" to each length of rail -plus the fact that it has become common to to solder trace wires to the ends of the rail and solder those together too. (This has more to do with track circuiting than power conduction though). Most of my friends using track power at Gauge 1 Scale use a 6 Ampere rated cable for the "tap wires" to each length of rail and a 30 Ampere rated house mains "Twin and Earth" cable for their supply wiring. 

http://www.cabbagepatchrailway.co.uk/mls/g3/eu cable.pdf 

regards 

ralph


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## docwatsonva (Jan 2, 2008)

I have used track power on 2 different layouts over the past 15 years. I use brass track and also have Split Jaw rail clamps on every connection. I might add that I have removed all my factory connectors and attach the rail clamps directly to the rail, not over the rail joiners. I think that's important. Currently I have about a 150 ft. outside loop with only 2 power connection to the track. One near the power supply and one furtherest away. I never had a power problem except through some switches. Switches can be a problem because of they way many of them are wired. If, for instance, you have 2 switches with a section of track between them, it might be a good idea to make a power connection at some point between the switches.

I use # 12 outdoor garden lighting wire to run power between the source and the track. I bury it in the ballast.

Doc


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## CraigW (Mar 9, 2012)

Doc, 
What size power source/transformer do you use? Btw I have also removed all the slide connectors and the split jaws are section to section.


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## krs (Feb 29, 2008)

Posted By ralphbrades on 02 Aug 2012 07:33 AM 
What you have to remember is that your brass rail is a better "buss bar" than your connecting cable...
To illustrate that point:


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## docwatsonva (Jan 2, 2008)

I use a Bridgewerks 15 amp supply with 2 of their remote control units. One RC unit powers my outside loop and the other powers the indise loop.

Doc


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## docwatsonva (Jan 2, 2008)

BTW, here's a photo of the power supply and RC controllers mounted inside a water tight tool box for easy movement from house to layout.











Doc


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## DKRickman (Mar 25, 2008)

Posted By krs on 02 Aug 2012 08:24 AM 
Posted By ralphbrades on 02 Aug 2012 07:33 AM 
What you have to remember is that your brass rail is a better "buss bar" than your connecting cable...
To illustrate that point:










So does that mean that you don't need to run any sort of bus when using code 332 brass rail, assuming that every joint is soldered or otherwise electrically sound? If I understand it correctly, a 50' run of track alone would have 0.054 Ohms of resistance, but if fed by a 12 gauge bus wire, the total resistance would be 0.112 Ohms ((R1+R2)/2), almost exactly double that of the rails alone. Is that right?


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## ralphbrades (Jan 3, 2008)

Yes! 

However the reason that G1MRA recommends that you wire each rail and not rely on the fishplates (or equivalent) is the fact that the ends of the rail are the bits that take the major part of the punishment of running locos. Most Gauge 1 track here in the UK uses ABS fishplates anyway -thus (in theory) each rail length should be self isolating. To quote a friend of mine "If yon B_gger stops on a length of track I know that the problem is there and elsewhere is nowt to bother with". 

regards 

ralph


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## DKRickman (Mar 25, 2008)

So does that mean that you don't need to run any sort of bus when using code 332 brass rail, assuming that every joint is soldered or otherwise electrically sound?Yes! 

Okay, then why do people do it? Is it a holdover from small scale modeling, in which a large bus wire is far superior to the rails? i.e. "We do it there, so surely we need to do it here too."


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## Greg Elmassian (Jan 3, 2008)

Too much focus on the rail and not enough on the losses at the joints. 

Solder jumpers between rails and power from one or 2 locations. 

Use anything else, and put your power feeds 20-30 feet apart IF you use rail clamps. 

All bets are off if you use the stock joiners in my opinion... 

Greg


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## CraigW (Mar 9, 2012)

Since I have it suppose I were to use 10 gauge THHN with four taps to the rails. I have split jaw connectors at all rail junctions and the I use 14 gauge for jumpers between every rail junction. Think that would serve well.?


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## cape cod Todd (Jan 3, 2008)

My first go outdoors I used a LGB 1amp starter pack with one track connection all rail joiners no clamps on a 125 of track and didn't have any problems. 
Now I have 500' of track half of which has rail joiners half has clamps to hold it together. I have a crest switching transformer with a train engineer. I used old extension cords linked one to another to provide power at 5-6 points. So far so good after 3 years. 
I don't think you need to worry too much about getting power to your rails it sounds like you will be fine with your 30-40 feet connections. Keep your track and pickup engine wheels clean and you will have no worries. No need to over kill it. 
Todd


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## Greg Elmassian (Jan 3, 2008)

Sounds great Craig.... but what do you mean by 4 taps to the rails, you mean 2 feed points of 2 wires each? 

Greg


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## CraigW (Mar 9, 2012)

I was going to do four feed points with two wires to each. Thought I might run two separate straight lines from the power supply with two feeds each.


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## Greg Elmassian (Jan 3, 2008)

Great, you will never have voltage drop problems and you will be able to run any loco combinations you want. 

Normally you "home run" each feeder line from the power supply to minimize voltage drops, but your runs should be short enough to share 2 feeds from each run. 

remember, with all the talk about different resistances in different materials, it's the connection points that have the potential to have way more resistance. Increasing the number of feed points as you have will minimize the impact of voltage drop at the connections. 

Greg


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