See picture below. top to bottom:
1. Control Bus Cable with RJ-H / RJ9 connector 4P4C. A 4 wire cable used between boosters and a command station. Maximum length is 300 feet.
2. Cab Bus Cable with RJ12 connector 6P4C. A 4 wire cable used for tethered cabs. Notice the 6 pin connector with only 4 slots being used. This is a regular Cab cable. Can be flat or coiled. Maximum length is 40 feet.
3. Cab Bus Cable with RJ12 connector 6P6C. A flat 6 wire cable used for the cab bus and for the Power Cab. When used with the Power Cab this cable carries full track power AND Cab bus. The Flat 6 wire cable used for the Power Cab is custom made to our specifications and only available thru NCE. Do not attempt to use any other cable. Any 4 or 6 wire cable you purchase from other vendors will not have the same size wires and will void your Power Cab factory warranty. For other applications the maximum length is 40 feet.
To buy a control bus / booster cable contact NCE directly at firstname.lastname@example.org or 585-265-0230 M-F 9a-4p eastern time. Control bus cables are custom made to a specific length. $.50 per ft.+$3+ shipping. Check or Paypal only. No CC.
The Power Cab is a special set of circumstances. It acts as a cab, command station AND track power booster. It is that last part that makes the big difference.
The 7 foot flat cable supplied in the original Power Cab kit is indeed a heavy duty 6 wire 7’ cable with 24ga. conductors.
The DC power supply input AND the DCC output BOTH go through that flat cable.
Depending on the load that cable could actually have 2amps of DC input AND 2amps of DCC output going though it at the same time!
This situation ONLY applies when you are using the Power Cab by itself with NO BOOSTER.
When you are using the Power Cab with a 5 amp system box (Ph-Pro) or a 5 amp booster (SB5) then the heavy duty cable requirements are not relevant since the Power Cab is NOT putting power to the track.
The booster is doing that instead. In this case the Power Cab is in “Pro Cab Mode” The command station and the track power booster in the Power Cab are OFF. In Pro Cab mode cables with smaller conductors will work fine.
Most telco cables use 26, 28 or even 30ga conductors. Also some of them will have some pairs flipped on one end since they are designed for analog voice signals.
Everything in DCC is digital data so the cables are “pass though” the same colors and pins on BOTH ends. Be very careful NOT to use cables with flipped pairs.
The ONLY thing that matters is that the cabs get a minimum of 8v DC power on the cab bus, or they will not function correctly.
A minimum of 8v DC as measured on the UTP Panel and cab bus cables between pins 2 (-)/ GND and pin 5 (+12VDC / Black and Yellow.
Smaller conductors / wires will have more voltage drop.