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Which wire gauge do I use?

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  • Member since
    January, 2009
  • From: Peotone, IL
  • 71 posts
Which wire gauge do I use?
Posted by train_frk-0079 on Saturday, January 31, 2009 5:13 PM

While I was starting to lay the track to my yard, I ran into a problem.  What gauge of wire do I use?  I know from my previous DC layout that electrical power gets lower the farther it travels.  If I go about 12ft., what gauge of wire do I use for the bus?  What gauge for the feeder wires?  Anybody experienced in wiring, or knows what they are doing, sound off.

Peace

Peace and love is all this world needs!! Ryan
  • Member since
    February, 2002
  • From: Westchester NY
  • 1,559 posts
Posted by retsignalmtr on Saturday, January 31, 2009 6:15 PM

it depends on the length of the run. a 12' run could use 16awg or 18awg wire for the buss with a 20awg to 24awg feeders to the rail from the buss. my buss run on my n scale layout will be 70' long using 14awg stranded wire with 20awg for the feeders. i used 14awg because i got it for free and had it on hand when i began building my layout.

  • Member since
    August, 2006
  • From: Franconia, NH
  • 2,107 posts
Posted by dstarr on Tuesday, February 03, 2009 11:51 AM

 #16 AWG (the size wire used in lamp cords) is enough for buses on all but the largest layouts.  Lots of people use #14 AWG house wire 'cause its readily available and mechanically rugged.  Electrically its bigger than necessary, but that doesn't hurt anything.  I don't use #12 AWG house wire because it is too stiff to bend easily with long nose pliers. Feeder wires (short feeders that is) can be thinner.  #22 or #24 AWG or even smaller works. 

  You can find a "copper wire table" on the Internet.  Such a table will give you the diameter in inches and the resistance in ohms per foot, or ohms per 1000 feet.  

As a rule of thumb, the wire is thick enough if the voltage drop is less than one volt. Voltage drop V = IR where I is current (in HO use 1 amp for planning purposes) and R is the resistance of the wire going out AND coming back.  Or, for HO, just keep resistance down below one ohm.  

  • Member since
    October, 2004
  • From: Colorful Colorado
  • 8,496 posts
Posted by Texas Zepher on Tuesday, February 03, 2009 1:48 PM

train_frk-0079
What gauge of wire do I use?

What size do you have laying around?

I know from my previous DC layout that electrical power gets lower the farther it travels.  If I go about 12ft., what gauge of wire do I use for the bus?

In my opinion 12 feet is not long enough for a bus.  Just run two wires down the center of the yard (crosswise to the track) connecting one to each left rail and the other to each right rail.  The "bus" then becomes the width of the yard.  In general the size of a wire needed in bus has more to do with the number of locomotives and/or power consumption demanded on the track being wired.  Very few people have 30 feet and longer wires where the voltage drop becomes a factor - and then once again only if a lot of current is needed at that far end.  If this is a coach yard that will contain bunches of lighted passenger cars that have incandesent lamps in them the gauge might need to be quite big.  If this is a freight yard and there will only be one locomotive at a time working it, the gauge can be small.  

What gauge for the feeder wires?

I like small solid wire (like 22 gauge) because it is easier to solder to the rails.

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