Brake Circuit Protection

[Aerowood]

Is there any kind of circuit protection on the normal brakes before the controller and on the break away switch circuit?

[thecatsandi]

THE F-250 has a 15A or 30A fuse upstream of the Brake controller. I am pretty sure my trailer has a breaker upstream of the break-a-way switch.

[markdoane]

Use a 20a circuit breaker going to the breakaway switch, unless it has three axles, then use a 30a (with larger wire)

[Aerowood]

Thanks I'll put the circuit breakers in. Do you know what a single axle 12" brake draws?

[markdoane]

About 3 amps per magnet.

[thecatsandi]

Originally Posted by Aerowood

Thanks I'll put the circuit breakers in. Do you know what a single axle 12" brake draws?

Size the breaker for the wire. Not the load. Of cource be reasonable. If you are using 10 Ga wire I would not put a 50A breaker on the line. 15-20 should sork fine if the wire is 14GA or larger.

[Aerowood]

That's what I'm trying to figure out. I have nothing right now so I need to pick the wire size. I think I'll go with 12GA then with a 15amp C/B. Thanks

[NevadaGeo]

My hydraulic/electric system required 10 gauge, and 30 amp fuse. Probably can find out by checking with brake company.

[lewster]

If you plan on using a circuit breaker on your towable's brake circuit, be sure that it is the 'auto-reset' type. If you use a fuse or normal CB and the circuit fails......YOU HAVE NO BRAKES!!!!!!!!!!!!

With the auto-reset type, a fault will click the breaker off, but it will reset and click off again...allowing some current to pass thru to your brakes so you still get some stopping power. With a blown fuse YA DON'T GET NUTTIN'!!!!!!!

[Aerowood]

I was planning on using a circuit breaker but had not though of an auto resetting, thanks for the heads up.

Kip

[Over59]

I have separate auto reset breaker on each axle. I will be adding in parallel a smaller amp fuse wherein a light red light comes on if it blows. That way I will know I need to check the brakes on that axle while the auto reset maintains some breaking power. I don't trust I would feel the difference in a normal stopping situation.

[HowieE]

Originally Posted by Over59

I have separate auto reset breaker on each axle. I will be adding in parallel a smaller amp fuse wherein a light red light comes on if it blows. That way I will know I need to check the brakes on that axle while the auto reset maintains some breaking power. I don't trust I would feel the difference in a normal stopping situation.

Very interesting to see someone else thinks as I do. I had just suggested to another posting that they install seperate fused and indicater lights on each brake location as a safty/indicater. Caught a bit of flack for it but glad you have an understanding of electronics and agree.

[Bill C.]

I am replacing the brake assemblies on my 1984 Airstream Excella. I just ordered brake assemblies that are rated for 7000 lb. Axels. Is this "overkill" and will they work? thanks!

[Bill C.]

I am looking into re-placing the electric brake assemblies on my 1984 Airstream Excella which has three axles. The larger magnets will consume about 5 amps each x 6 wheels which equals 30 amps total in my mind. The brake circuit, I believe, has only a 20 amp fuse in the 12 volt fuse panel (or, isn't there any fuse at all in the wiring to the electric brakes?). I am thinking that this may be "overload". Are there any experts out there who may know the answer to this problem? thanks!

[HowieE]

If the brakes are 12x2 in. they will be OK. Not sure where you got the 5 amp draw on the magnets. Most magnets draw about 3.5 amps per when fully applied. You should never need full application as you will lock them up first.

A 30 amp circuit braker shoud be fine. However I would suggest you up size the wireing in the truck to #10 as the factory wiring is not sized for 6 brakes and you will see a voltage drop over the undersized wire.

Now all that said I am currently drawing 21 amps with 6 brakes and have No Brakes and not sure what the problem is just yet. But then again when something is broken all bets are off.

[Bill C.]

The Brakes are 12" x 2" but I asked the salesperson what the amp draw was on the 7000lb. rated brakes and he quoted 5 amps as, according to him, the only difference between the 5600lb. rating and the 7000lb. rating is the size of the magnet. He claims that there is no difference in the linings at all. Only that it is a larger magnet. And, after looking at the schematic in my service manual, it doesn't appear to have any fuse whatsoever between the umbilical cord and the brakes. Thanks for answering and I hope that you get your problem fixed soon.

[markdoane]

Can't add much except that the magnets have different Dexter part numbers. The lighter duty magnets have white wire, and the heavier one are black wire.

Usually the overcurrent protection for the brakes is a breaker in the 12V power line going into the brake controller. Either on the firewall or under the dash of the tow vehicle.

[Bill C.]

In a follow-up to my own question of replacing my former 5200 lb. rated 12" x 2" electric brake assemblies with 7000 lb. rated electric brakes on my 1984 Airstream, I made telephone calls to the Airstream factory and to Dexter Manufacturing who makes the brake assemblies--both concurred that as long as I was replacing the "entire assemblies" and not just the shoes or the magnets, I will be able to upgrade the brakes to the 7000 lb. rating. However, you can not just upgrade the shoes or the magnet, you "must" upgrade the entire brake assembly. Special thanks to all who answered my questions regarding these issues.