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
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.
#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.
What size do you have laying around?
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.
I like small solid wire (like 22 gauge) because it is easier to solder to the rails.
go with 16, 18, 20, or 22 Do not use 12. 12 gauge wire is stiff and it has a nickle core plus you risk overload if you use this. Use solid for the feeders and stranded for the bus.
How can larger wire cause an overload? The only strain larger than necessary wire puts on anything is on your wallet. And both rolls of #12 I have are all copper strands, there is no nickle core.
–Randy
I doubt 12AWG has a nickel core. Nickel is expensive, so it would not be used with wire. Plus it increases resistance in the process. Not a desireable outcome for electrical conductors.
Some wires are copper clad aluminum or steel, but they have specialised applications and often are not found at the local hardware store.
I fail to see how heavy wire would cause an overload. My CT test set’s power supplies have no trouble driving large currents through much heavier wires.
It’s been 9 years since the OP asked this question. I hope he’s got it figured out by now.
I used 18 gauge bus wire. It was a big, room filling layout with bus runs of 25 feet. I typically ran 4 sound engines at a time, with lighted passenger cars and cabeese. I had a few DCC controlled turnouts, too.
I never had track power issues.
Sure, 12 gauge bus wire is nice, but for anything less than a club sized layout it’s overkill.
Uh oh, someone is necroing 9 year old topics and people answering like it is still a current issue, no pun in tended.
SOP for this forum! Look at dates before answering might be a good idea!
Most forums that have been a member of, it is considered bad form to dig up old posts. I think it should be here as well.
Or even against the rules in some case I’ve seen. I can only assume topics get necroe’d here because someone does a search and finds a topic of interest and doesn’t check to see if it is current or dredging up ancient history.
In some cases people post or answer questions to members who are no longer living. And then others come in like lemmings and follow suite. [:o)]
Model Railroading, though, is not a static hobby, and there are always new modelers just starting out. The questions are no less valid now, although some of the answers may reflect newer thinking and newer materials.
9 years ago, no one was willing to admit that a small layout didn’t really need a 12 gauge track bus, for example. We were told to make “wet water” with water and dish soap and make a mess by spraying it around, rather than simply dribbling on a small amount of alcohol from a pipette.
Old threads can have their place.
sounds to me like “****** if you do and ******* if you don’t”…imagine that, a newcomer using the search instead of post the question…yup, bet 10 dollars to donuts, someone would have advised him to do a search…
it has to do with voltage if you have larger wire more volts will be flowing through it. 12 is only used for G Scale since it is outdoors and it runs off of a car battery or a transformer. 20 is the feeders for HO and S and O Scale and 16 is the feeders for N and Z. I have gauge 20 wire I will use this for my HO trains no use using it for N Scale I am stuck with my black wire which is 22. Here are the gauges and the link to them don’t overload your layout. Z Scale Buss 16 max is 14 Feeders 24 to 22, N Scale Buss 16 max is 14 Feeders 24 to 22, HO Buss is 16 max is 12 Feeders are 20 or 24, O Buss is 14 max is 10 Feeders are are 16 or 22, S same deal, and G Scale Buss is 12 max is 10 you can go up to 14 Feeders are 14 to 20. https://ncedcc.zendesk.com/hc/en-us/articles/115003102886-Recommended-Wire-Gauges-by-Scale
How about 10 years later? [(-D]
He finally got around to answering (incorrectly) the question I asked him a year ago.
–Randy
I really think you need to go back and study up on basic electricity. A heavier wire has more CAPACITY, but it can’t push more ‘volts’ all by itself. You have a voltage source, the power pack, or car battery, or what have you. It’s 12 volts (ok, 13.8 for a car battery). If you run 50 feet of #22 wire and measure the voltage with a meter at the other end, it’s going ot be the same 13.8 volts. If you repalce the #22 wire with 50 feet of #12 wire, you are claiming the voltage will be higher - no it won’t, it can’t, that violates the laws of physics. It will be the same 13.8 volts.
And the other part of the current flow, the amps - you don’t ‘push’ amps. You can use a 2 amp power supply to run a 1 amp load, you can use a 20 amp power supply to run a 1 amp load. The 20 amp load doesn’t ‘force’ 20 amps into the 1 amp load.
The wire size difference is the voltage DROP, or loss under a load. If you repeat the same experiment with the #22 and #12 wire, but this time also connect a 2 amp load at the far end, the #22 wire will
Who ever did a search and found something on this forum is a miracle worker, for sure.
Easiest thing to do it use Google. Half the time, if something come sup here, and I google the question, I end up getting a link to an old forum thread on the same subject.
–Randy