Wire Size to Brake Magnets - Is it Worth It?

Just keep in mind that EACH BRAKE MAGNET will pull 3AMPs when hit with 12VDC. A single axle will only have 6AMPS of DC current to deal with.. Two Axles will have 12AMPS of DC current to deal with...

I believe my Electric Brakes are only receiving 5-6VDC after being corrected by the BRAKE CONTROLLER to keep the brakes from locking up with full brake pedal applied. In my case using a single axle or two brake magnets would relate to around 3AMPS being drawn by both brake magnets when I push down the brake pedal.

I have no problems with my brakes the way they were originally wired stopping my 4000Lbs trailer... I base this on being able to make my trailer brakes slide or lock up with ease and able to adjust for that with a lower BRAKE CONTROLLER setting..

Bigger trailers with more brake magnets involved may indeed need larger size brake wiring conductors.

Roy Ken

Yeah, I'm kind of interested in this for my triple axle toyhauler. What would be the best way to wire all this up? Anyone have a diagram?

Mine does a pretty good job, but I figure more is always better when it comes to brakes. :)

I rewired my Starcraft brakes, replacing the series connected wiring with a star configuration. I led both wires from each brake assembly forward in conduit to a terminal strip. The terminal strip is mounted in a box on the tongue. Since all my wiring is inside on the terminal strips, I can easily check if power is present or even measure current (if I desired).
I see a lot of posts where 10 AWG is the wire of choice but I have miles of 14 AWG on hand so that's what I used. Brakes are functioning well.

I have a Prodigy P3 controller. My brakes will lock up at about 7 volts on the Prodigy. That is about 60% of the available voltage. Increasing the wire size probably will do nothing as the controller will lock the brakes with the wire I have. Sending more current to the brakes will not accomplish anything.

The answer to your question, what voltage does it take to lock your brakes? If you are unable to lock brakes make sure they are in good condition no grease contamination and adjusted properly. If that is OK then a larger wire may give you more braking effort.

Is this a preventative maintenance item or are you trying to solve a brake problem? For example the controller is always at the max setting.

For preventative maintenance here are some things to look for:

1) Ensure crimps are good quality and sealed from the elements - just because they are factory does not mean they're good.... It's likely they are exposed to the elements and the wires will corrode over time, causing the connection to gradually get worse.

If the crimps are of the type where you can see the cut end of the wire and if you move the insulation side of the wire and can see wires on the cut side moving, then I would call that a "bad" crimp. That is also exposed to the elements....


I'm not convinced that wire nuts are good either.


2) Ensure there are no "extra" connections in the system - main run pieced together from smaller pieces (the only fix here is to re-wire).

3) Watch for problems with wire run through axle tubes (grommet rotted or missing for example)

4) Dexter and Lippert have a minimum wire gauge of 12 in the case where the axle is less than 30 feet from the hitch. It's 10 if the distance is more than 30 feet or for any tri axle trailer. Don't assume that the trailer manufacturer followed those minimum guidelines.

If you end up redoing the wire because of (#2 or #4) I would suggest at least 10 gauge as the main run.

The only way to make things worse is if you end up making bad connections and the brakes don't get the power they need.

When we had our 5er, the left front wheel would lock up on harder stops, but none of the rest would slide even when standing on the brakes.
Starting at the main lead near the wheels, I rewired the setup with 14 gauge wire using an equal length method. That means all four brakes had the same wire length between the main connect point and the brake pucks. From that point on, the LF never locked up, and it was actually a pleasure to tow afterward. All four wheels braked evenly, no pulling or locking. I wish I had done it not long after purchasing the unit.

I use a bit different connection method - I used ring connectors on each connect point, crimped, soldered and sealed with liquid insulation, then taped. Using small bolts, I connected each set of ring terminals and subsequently sealed and taped those connections.

Hmm, mine sure didn't look like 10 gauge wire, more like 14, it's pretty small and flexible. Thanks for the info, I'll have to do some more checking.

At 3 amps max on each brake, you'll have a total of 12 amps at full braking. 14 gauge handles 15 amps, 12 gauge is 20 amps. If the factory wiring on your trailer from your TowVehicle connection point is at least 14, you'll be ok. This circuit doesn't see full load very much, and for very long. Chances are the normal current across this circuit ranges from 0 to 1 or 2 amps per brake - 0 to 8 amps on the main line.

It is preferable to have a heavier mainline to lessen current drop over the length, however. What size wire is on your TV? I ran 10 gauge on our '93 GMC. I think the factory brake wire on our new '12 GMC Canyon is 12.

I have no idea what the wire is on the truck. I bought it with the wiring already in place. I guess that is one of the first places to start checking. This is on a 1-ton dually so the plug may even be factory. I wonder if there is any way to tell?

Thanks for the information.

Don't forget the one wire that might be the most important. Grounding Wire the heavier gauge the better 10AWG minimum going thru Plug. If, your running lights on Trailer dim down when applying brakes or your Turn Signals dim. Bad ground wire 99% of the time.

Happy Trails