QUOTE (philg @ 13 Aug 2008, 23:23)
<{POST_SNAPBACK}>A really cheap and reliable bus bar is a piece of cheap HO track..mounted under the baseboard..already finished and insulated??
Phil
***Good for a control panel yes, but not for a layout bus.... this would result in droppers that are long on anything other than a shunting plank type layout.
a layout bus should ideally follow the main rail layout above the board with branches where neeed to accommodate yards and branch lines etc. and Power should be fed to the track via droppers that are not more than say 300mm... providing they are kept to this length then finer wire is OK.
It should ideally be 32/.2 for a small to medium layout, larger for a biggish layout - and much, much larger for a very big one - up to the equivalent to 10 gauge or about 3mm diameter copper (about 9sq mm).
Unless you have a layout larger than the average garage, 32/02 will be fine, so most need never worry about larger gauges.
None of this is about current carrying ability.... as mentioned earlier by railstimulator, its all about avoiding voltage drop under load.
The bus should either be twin wire twisted about 4 turns per foot or two separate wires not less than 100mm apart. Close wires that are not twisted will create an inductance when the power bus is under load that will both greatly increase voltage drop and significantly distort the DCC waveform.... not a problem on a small layout but as size grows, the effect becomes a real problem.
The worst bus is that B awful copper tape ZTC push ...It often gets placed either side of a bit of 2x1 to keep it tidy and when its done like that it makes a hugely inductive power bus thats really just a long capacitor, and layouts using it should like that should both terminate the bus and also restrict each bus length to no more than 2 or 3 metres per section to avoid problems...
regards
Richard
DCCconcepts.
