Author Topic: electric brake controller wire size  (Read 3334 times)

Offline Rick 74 MC-8

  • Sr. Member
  • ****
  • Posts: 262
electric brake controller wire size
« on: June 01, 2014, 05:37:31 PM »
I'm installing an electric brake controller on my MC 8. Just wondering what wire size would be recommended for that approximate 40 foot run. I've got 10 gauge I'm thinking that might be overkill. any suggestions

Thanks Rick 74 MC-8
About 20 Miles West Of Chicago

Offline luvrbus

  • Hero Member
  • *****
  • Posts: 19550
Re: electric brake controller wire size
« Reply #1 on: June 01, 2014, 05:54:36 PM »
14 gauge for 2 axle brakes is the norm,you use whatever gauge of wire that leaves the controller box make no difference to the brakes

good luck
Life is short drink the good wine first

Offline Jim Eh.

  • Hero Member
  • *****
  • Posts: 743
  • Excess in moderation
Re: electric brake controller wire size
« Reply #2 on: June 01, 2014, 05:58:48 PM »
One way of doing it is rather than a heavy gauge wire for power out from your controller to your trailer plug, why not run a lighter gauge signal wire from your controller output to a relay (installed by you) located at the rear of the bus? I understand there are plenty of 12v circuts at the rear panel. Then the heavy current will not have to travel all the way from the front of the bus.
BTW, how many braking wheels 4 or 6?
Jim Eh.
1996 MC12
6V92TA / HT741D
Winnipeg, MB.

Offline Rick 74 MC-8

  • Sr. Member
  • ****
  • Posts: 262
Re: electric brake controller wire size
« Reply #3 on: June 01, 2014, 06:12:53 PM »
The trailer has 2 Axels so 4 brakes. With a relay I would not be able to adjust the braking. Thanks Clifford 14 gauge is is

Rick
About 20 Miles West Of Chicago

Offline Len Silva

  • Hero Member
  • *****
  • Posts: 4086
  • Angle Parked in a Parallel Universe
    • Leonard Studio
Re: electric brake controller wire size
« Reply #4 on: June 01, 2014, 06:26:23 PM »
I would go up at least to 10 ga.  The brake controller is designed for cars and trucks where the trailer is only 20 feet away.  Find out what the maximum brake current is then use the distance from the controller to the brakes to find the appropriate wire size.

Trailer brakes run about 4 amps each at max braking.  4 brakes is 16 amps and if the axle is 60 feet from the controller, you'll be dropping about 1 volt with 10 ga and about 1.5 volts with 12 ga.
« Last Edit: June 01, 2014, 06:36:07 PM by Len Silva »

Hand Made Gifts

Ignorance is only bliss to the ignorant.

Offline luvrbus

  • Hero Member
  • *****
  • Posts: 19550
Re: electric brake controller wire size
« Reply #5 on: June 01, 2014, 07:25:54 PM »
I have 2 -7000 # Dexter axles under my trailer they are 2 amp ea at full braking 4 amp sounds high for small trailer brakes my pre wired Chevy pickup is 18G so are the brake drums magnet wires on the trailer 10,12,14 gauge will work the magnets will engage with only 10.5  volts so says Dexter and using 14G I had 12.3 with the engine running and 10.4 with it off 
« Last Edit: June 01, 2014, 07:33:14 PM by luvrbus »
Life is short drink the good wine first

Offline bevans6

  • Hero Member
  • *****
  • Posts: 6006
  • 1980 MCI MC-5C
Re: electric brake controller wire size
« Reply #6 on: June 02, 2014, 02:27:07 AM »
Tekonsha (who makes good controllers and is what I happen to use) specifies a 10 gauge wire and a 30 amp breaker for the line to the brakes.  That is because they also specify a 6 brake capacity (three axles) and the brakes can take up to 5 amps each.  14 gauge is only good to 15 amps, 12 gauge is good to 20 amps. if you believe the charts.  I pulled in a 10 gauge wire, being a believer...

Brian
1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Allison MT-647
Tatamagouche, Nova Scotia

Offline HB of CJ

  • Hero Member
  • *****
  • Posts: 1765
Check The Specifications On The Controller
« Reply #7 on: June 02, 2014, 03:26:19 PM »
The controller specifications may say what kind of minimum voltage/amperage is required AT THE BRAKES for everything to work.  You can then do it by calculating the OHMS total from your dash controller to the actual brakes that will be working.  Easy to do the math.  You MIGHT then find that considering the long run, a much heavier wire MAY be necessary.  Or maybe not.  HB of CJ (old coot)

Also strongly consider running a dedicated HD grounding wire, just for the trailer brakes.  Might help greatly.  Lots of times a hitch by itself is a lousy ground.  It that fails, consider a dedicated auxiliary battery placed on the tongue on the trailer, wired up like one of the starting batteries, with its own charging and grounding wires.  Sometimes this helps greatly.  Ah...British speeel chzk. :)

Your trailer brake circuit wiring may be sub standard also.  Except for all the unknowns, everything is fine.:)

Offline Rick 74 MC-8

  • Sr. Member
  • ****
  • Posts: 262
Re: electric brake controller wire size
« Reply #8 on: June 02, 2014, 03:36:52 PM »
I ended up pulling a 10 gauge. Sorry Clifford but I found a 50 foot piece in the shop so I used it. ended up cheaper than buying new 12 gauge. thanks for the help this board is a valuable resource


Rick



 
About 20 Miles West Of Chicago

Offline luvrbus

  • Hero Member
  • *****
  • Posts: 19550
Re: electric brake controller wire size
« Reply #9 on: June 02, 2014, 04:04:19 PM »
That should work Rick I never used any controller other than a Hayes I had a air activated Hayes on the bus a fine piece of hardware it was
Life is short drink the good wine first

Offline Dave5Cs

  • Hero Member
  • *****
  • Posts: 3348
  • 1979 MCI MC5Cs 6V-71 644MT Allison, Roseville, CA
Re: electric brake controller wire size
« Reply #10 on: June 02, 2014, 08:51:45 PM »
Rick go with Ready Brake it is a lot easier, Just saying. ;D
Dave
"PATHFINDER" (PFBus)
 1998 Jeep TJ (PFTOED)