Bus wiring

[Dobson]

I have been reading a lot about bus bar wiring and I was wondering what everyone uses for the bus bar under their table.  I was going to run a few of them and wanted to get the right piece of metal or bar.

 

thanks,

Brian

[lionelsoni]

Busbar is typically far heavier than anyone would need for toy trains:

Wire of a suitable gauge is much more appropriate.  Where did you see busbar recommended?

[steve24944]

I think that when most people refer to bus wiring they are referring to a heavy gauge wire run from your power supply off your transformer, Such as the A-U or the B-U posts on a ZW to a distribution point such as a terminal strip located at a handy location under the layout benchwork.  From that  terminal strip a lighter gauge wire can be used to run the connection to the track or accessory that needs power.  On my layout I  have a ZW and use the A and D posts for track power, and the B+C posts for accessories.  I run wire from the B post and C post to separate terminal strip and then use those terminal strips as a hub to power several accessories.  I have a modest size layout and use 18 gauge wire.  On larger layouts I read that some fellows use 14 gauge wire ( or for some even larger ) which is what is used to wire most homes.

Steve

[steinmike]

Brian:

I have three loops of 14 gauge wire running under the layout, one for train power, one for accessory power, and one for ground (which is shared between the two power sources - a venerable KW that provides power for switches and signals, and the TMCC TrainMaster.  I also have two smaller runs that carry 12VDC power for building illumination and street lamps.

Using "suitcase" connectors, I run leads from the loops to the track or accessories.  The feed wires to the track are soldered to the underside of the track for a good connection.  The advantage of having the "bus" loops running under the table is that they are continuous (unless track with rail joiners / pins) and thus there is no voltage drop across the layout due to loose / rusted conntectors. 

It certainly makes it easy to run additional track power feeds as needed - but might not be the best approach if you want to have separate power blocks to selectively power lengths of track in which case you're going to need additional wiring running for the toggle switch at the control panel - easire, I guess, if the toggle switch is located right at the feeder wire (and then you would need some form of remote control so that you could move around to flip the toggles).

[BATMAN]

A terminal strip.

 

                                                           Brent

[BATMAN]

A terminal strip.

 

                                                           Brent

[lionelsoni]

Steve, the wire size that you should have for safety doesn't depend on the layout size but rather the transformer size.  The ZW can put out 15 amperes, which is the same current as a typical residential branch circuit.  That's why houses are wired with at least 14 AWG wire and why you should use the same stuff for your layout.  Eighteen AWG is heavy enough for only 7 or 8 amperes.

There is a way around the need for heavy wire with large transformers.  If you add supplementary circuit breakers on the individual outputs, then the wiring that those outputs feed needs to be only heavy enough for the rating of those circuit breakers.  For example, 5-ampere breakers would protect 20 AWG wire.  The lower current rating is not usually a problem, since you are probably not counting on each output's providing nearly the full 15 amperes that it could put out.

Another benefit that comes from adding circuit breakers this way is that you are protected from situations where two of your transformer's outputs get conneted together.  The transformer as built has no protection whatsoever for this case.