In his March 2005 column (p. 6), MRR Editor Terry Thompson spoke favorably of attaching "long (12"-14") pieces of 14 gauge bare copper wire to the power buses every four feet or so, then [attaching] the feeders to those."
At the 2006 NMRA convention, I had the privilege to meet Mr. Thompson and ask him about this technique. I question him about the risk of a short with this approach. Essentially, he said the solution was to run in opposite directions the two bare copper wires at each location. I was sold; besides, I have a lot of surplus bare copper wire that was the ground wire in the 12-gauge indoor household wiring that I bought for the bus.Now that I have completed laying my main line and have all of its feeder wires dropped, I am ready to run the power bus and connect the feeder wires. However, after reading other advice on using heat-shrink tubing to cover the splices at traditional connections to the power bus, I am not sure which technique to use? I ask myself, "If some folks advocate covering up small traditional power bus splices, how good of an idea is it to have foot-long bare copper wires exposed?"I would appreciate any thoughts or advice.
I would think it is simply a matter of whether or not anything is ever going to come into contact with the bare supplementary bus wires....like your back or head if you are ever under there...and if the wire is then likely to be pushed into contact with anything to create a short.
Otherwise, it is akin to the proverbial tree falling in the forest. If the bare wires are there, and are never going to be brought into contact with anything else (that includes not sagging over time somehow) do they really exist as a problem....No.
If you are going to use bare copper wire as sub-buses...effectively...then I wouldn't worry about bared joins to the bus or to the feeders on the other end of those sub-buses. If you are not concerned about shorts with the bare copper, then you needn't be concerned for the method of joining them at bared ends of the feeders. Bare joins on bared wires...what's the diff except a wee bit added on to what's already bare?
I just soldered. It's a bit awkward, but it is positive. I also made sure the wires were supported and out of the way such that a short between bared solders is most unlikely.
I have used this product. It works great, and can be bought at hardware stores, or Home Depot.
http://www.plastidip.com/home_solutions/Liquid_Tape_-_Electrical_Insulation
Joel
collingswood_don wrote:In his March 2005 column (p. 6), MRR Editor Terry Thompson spoke favorably of attaching "long (12"-14") pieces of 14 gauge bare copper wire to the power buses every four feet or so, then [attaching] the feeders to those." At the 2006 NMRA convention, I had the privilege to meet Mr. Thompson and ask him about this technique. I question him about the risk of a short with this approach. Essentially, he said the solution was to run in opposite directions the two bare copper wires at each location. I was sold; besides, I have a lot of surplus bare copper wire that was the ground wire in the 12-gauge indoor household wiring that I bought for the bus.Now that I have completed laying my main line and have all of its feeder wires dropped, I am ready to run the power bus and connect the feeder wires. However, after reading other advice on using heat-shrink tubing to cover the splices at traditional connections to the power bus, I am not sure which technique to use? I ask myself, "If some folks advocate covering up small traditional power bus splices, how good of an idea is it to have foot-long bare copper wires exposed?"I would appreciate any thoughts or advice.
Actually it depends on how long your feeders need to be. A given size wire has a given voltage drop with regard to it's length. In a previous post I stated a #20 AWG feeder should not be more than 12" long MAX! I actually keep mine as short as posible.
But to answer your question, if your feeders have to be overly long for some reason than by all means, use #14 to make em longer. The result is less voltage drop, which is the reason for keeping feeders short in the first place.
The beauty of DCC is that you can fork your busses, Tee and or branch your busses. If you have a #12 bus you can can actually service two tracks with 1 bus. Of course if you have a double mainline track setup 150' long with 8 loco's running on it at the same time, on each track, common sense would dictate 2 busses, 1 for each track.
Total load: Loco's, switch machines, other devices.
Voltage drop: The distance at which the voltage drops so the load can no longer be carried because the electrical force is no longer enough to do so..
Lets suppose you have a yard 6' long 4' wide. You have two choices.
Run 3 or 4 busses down the legnth of the yard OR run 1 buss down the center and #14 branches off of the #12 and attach 6" #20 feeders to the #14 branches. Electricly both are sound choices. If your running low on #12 and have plenty of #14 thats the way to go. If your using 3' sections of Flextrack it only makes sense to attach feeders every three feet. Liquid Tape at HD works fine with low voltage, don't use it for 110/220.
I use #20 feeders soldered to the bottom of my rail. I solder the feeder to the bus keeping it short, I like 4-6". If It had to be more than that I would add whatever length of # 14 to enable me to keep my feeder 4-6". I found that #12 stranded don't like to go into Digitrax DCS-100 terminal connectors so I use #14. A few feet's worth of it doesn't amount to nothing voltage drop wise.
Jules
This kind of goes with this thread.... I'm about to start wiring a bus. I am planning 14 gauge solid wire for the bus, and I have 20 gauge stranded feeders to connect to it. I was planning to use bare wires for the bus, suspended under the benchwork with eyelets. Then I was planning to solder the feeders directly to the bus (using a BIG soldering iron). I figure bare bus wires because I don't know how to strip a section of insulation off the center of a wire. Bare bus wires isn't any worse than bare track rails (right). Is there a good technique for stripping insulation? If so, I might be tempted to use insulated bus wires.
Jim
If you have good control on what's going on under the layout, you could just as well use bare bus wires! Think about it, what are the rails? there's no need to protect teh joints unless you don't feel confident about what could move around. And there are certainly times where that could be the case.
Jeff But it's a dry heat!
Wire strippers are available (I got mine at Home Depot) which easily strip wires in the middle to allow making a tee connection. They are not cheap, but it makes the job a piece of cake. Mine has a removeable plate on it to use when stripping the ends of a wire. Removing the plate lets the stripper grip the wire for center stripping the insulation. It has notches for gripping many different sizes of wire. I got it for making tee joints, but I always use it for stripping the ends of wire because it works so well. I make my tee joint with the middle stripped buss wire and end stripped feeder wire, and then use the liquid insulation to finish the joint.
Have fun. Hal
jim22 wrote:Bare bus wires isn't any worse than bare track rails (right).
Is there a good technique for stripping insulation?