As part of correcting a no brake issue on our trailer (small 23 foot), I decided to freshen up and rewire some components of the braking system.I will quickly admit, I knew/know very little when it comes to the intricacies of trailer electrical system(s) and I am learning "on the job". So far, I have replaced the 7 pin cable, junction box, emergency brake cable component and run new brake wiring from the junction box to each of the four, soon to be replaced, brake assemblies. All the wiring has been laid out, but many actual connections are still pending.One of the latest stumbling blocks is a small device at the front of the trailer (previously hidden under an amateurish bo-jack cover which is like a hand formed thin plastic cover, open to the elements at the bottom - original to the trailer). It is attached to the front frame cross member, is about 2 x 1 x 2 inches high, and has two threaded studs, to which four cables are attached by ring terminals. I was unable to fully inspect it, due to impending darkness, but it has BAT etched in it, and one of the wires goes to the black wire of the 7 pin cable. I think another wire goes to the battery, but can't confirm that yet (due to wire loom). It is located right beside, but not connected to, a grounding screw in the frame. Because neither the grounding terminal nor this device are protected from the weather, there is noticeable corrosion.At the very least, I will be cleaning up the corrosion, but don't know yet what else needs doing.However, I am trying to determine what this device is, what it does and, whether it can be just cleaned up or needs replacing. Have done some internet searching and came up with either a busbar or stud type circuit breaker (the closest photo I could find is a Princess Auto 6 to 24v stud type circuit breaker).Any help is greatly appreciated, and sorry for the long post.Marv

There should be markings on the unit as to what amperage it is. It is no doubt a circuit breaker.Many different brands and amperage.circuit breakers

Enblethen,Thanks very much. One of the photos you linked to looks almost exactly like this device, so it looks like it is a circuit breaker. One of the things that caused me to hesitate in thinking it was a circuit breaker is the location (outside, fairly accessible to weather and road splash-up). Always figured circuit beakers were kept in closed, dry locations.Once again, thanks for your help.p.s. travel a lot from Vancouver BC to Denver Co along I-90 and quite like the Moses Lake and surrounding area.Marv

Many are mounted under the trailer tongue area with no protection at all. Some put them in a standard indoor electrical box with splices as well as circuit breaker(s).If you cannot find amperage mark, look at your converter. A common sizing is based off the converter output or the size of the wire between the converter and breaker.Many auto parts stores have them. Another source is marine stores which some have rubber covers for them.

Your description right down to the location under the frame says it's a circuit breaker. This breaker is for your interior wiring, but not the brake wiring. If your lights and electrical items in the trailer work you can put off replacing that breaker. Your brake wires should go straight to the brakes. Go thicker on the wire like at least 10 gauge. Best is to put a waterproof junction box on the tongue or under the front of the trailer. Take the one brake wire from your 7 pin to the junction box and then run 4 separate brake wires from the box to each wheel. Do not run the wire from the 7 pin to the first wheel and then jump from the first wheel to the second and so on. That it a surefire way to get poor braking performance.It's usually cheaper or at least easier to buy complete brake assemblies from someone like etrailer. These are complete units (brakes and backing plates and magnet) You just cut the old wire, remove 4 bolts and pull the whole brake assembly off. Put the new assembly on, tighten the 4 bolts and hook up the brake wire. Figure $200 per axle to replace. maybe it was 100 per axle I it's been a while since I looked.As far as the circuit breaker. You should have one wire going from the breaker to the breakaway box. From the breakaway box you should have a wire going to the waterproof junction box you added for your brake wiring. This wire gets tied in with all the other wires. Yes 6 wires all joined together inside that junction box. The other wire from the breaker is to the wires that feed the electricity into the coach.

Thanks everyone for the continued comments (massive learning curve for me, so lots of good advice).Initially, it was my intention to just replace the 7 pin cable and brake wiring. But as I got into it, I could see a bunch of corrosion locations, which I figured would bite me later so figured I would re-do/replace some obvious items. That is how I came upon the circuit breaker and as it was accessible, figured I may as well replace that too. Funny thing was, there were no markings at all on the old one, so I took it into an RV place and was advised to just get one which was the same amperage as the pedestal amperage for the trailer (in my case it is 30 amp), which is what I did.As the junction box was a residential box and it was absolutely crammed with wiring, all connected with typical residential marrettes and a lot of corrosion, I purchased an RV waterproof box and re-did the wiring connections.As to the brake wiring, I replaced with the same gauge wire and ran a single blue and white from the box to the centre of the axle(s) then pigtailed off a wire to each wheel. So, each brake has exactly the same length of wire running to it (don't know if that is relevant but the OCD in me said to do it that way).I did purchase a brake assembly for each wheel, and my next step will be to replace the old with the new.Marv

Electrical Help Needed | Good Sam Community

enblethen
Nomad
Sep 09, 2022
The pedestal amperage is not for the 12-volt system but for the 120-volt system.
The converter output amperage is one basic way select amperage of the breaker.
marpel
Explorer
Sep 09, 2022
Thanks everyone for the continued comments (massive learning curve for me, so lots of good advice).

Initially, it was my intention to just replace the 7 pin cable and brake wiring. But as I got into it, I could see a bunch of corrosion locations, which I figured would bite me later so figured I would re-do/replace some obvious items. That is how I came upon the circuit breaker and as it was accessible, figured I may as well replace that too. Funny thing was, there were no markings at all on the old one, so I took it into an RV place and was advised to just get one which was the same amperage as the pedestal amperage for the trailer (in my case it is 30 amp), which is what I did.

As the junction box was a residential box and it was absolutely crammed with wiring, all connected with typical residential marrettes and a lot of corrosion, I purchased an RV waterproof box and re-did the wiring connections.

As to the brake wiring, I replaced with the same gauge wire and ran a single blue and white from the box to the centre of the axle(s) then pigtailed off a wire to each wheel. So, each brake has exactly the same length of wire running to it (don't know if that is relevant but the OCD in me said to do it that way).

I did purchase a brake assembly for each wheel, and my next step will be to replace the old with the new.

Marv
opnspaces
Navigator II
Sep 08, 2022
Your description right down to the location under the frame says it's a circuit breaker. This breaker is for your interior wiring, but not the brake wiring. If your lights and electrical items in the trailer work you can put off replacing that breaker.

Your brake wires should go straight to the brakes. Go thicker on the wire like at least 10 gauge. Best is to put a waterproof junction box on the tongue or under the front of the trailer. Take the one brake wire from your 7 pin to the junction box and then run 4 separate brake wires from the box to each wheel. Do not run the wire from the 7 pin to the first wheel and then jump from the first wheel to the second and so on. That it a surefire way to get poor braking performance.

It's usually cheaper or at least easier to buy complete brake assemblies from someone like etrailer. These are complete units (brakes and backing plates and magnet) You just cut the old wire, remove 4 bolts and pull the whole brake assembly off. Put the new assembly on, tighten the 4 bolts and hook up the brake wire. Figure $200 per axle to replace. maybe it was 100 per axle I it's been a while since I looked.

As far as the circuit breaker. You should have one wire going from the breaker to the breakaway box. From the breakaway box you should have a wire going to the waterproof junction box you added for your brake wiring. This wire gets tied in with all the other wires. Yes 6 wires all joined together inside that junction box.

The other wire from the breaker is to the wires that feed the electricity into the coach.
enblethen
Nomad
Sep 08, 2022
Many are mounted under the trailer tongue area with no protection at all. Some put them in a standard indoor electrical box with splices as well as circuit breaker(s).
If you cannot find amperage mark, look at your converter. A common sizing is based off the converter output or the size of the wire between the converter and breaker.
Many auto parts stores have them. Another source is marine stores which some have rubber covers for them.
marpel
Explorer
Sep 08, 2022
Enblethen,

Thanks very much. One of the photos you linked to looks almost exactly like this device, so it looks like it is a circuit breaker. One of the things that caused me to hesitate in thinking it was a circuit breaker is the location (outside, fairly accessible to weather and road splash-up). Always figured circuit beakers were kept in closed, dry locations.

Once again, thanks for your help.

p.s. travel a lot from Vancouver BC to Denver Co along I-90 and quite like the Moses Lake and surrounding area.

Marv
enblethen
Nomad
Sep 08, 2022
There should be markings on the unit as to what amperage it is. It is no doubt a circuit breaker.
Many different brands and amperage.
circuit breakers

Forum Discussion

Electrical Help Needed

About Technical Issues

Related Content

Electric advice needed

Need electrical advice

2016 Palomini Electric Advice Needed

Electric brake controller needed?

Needing help with electrical plug