Burned Neutral Wires at the Buss in the Breaker Box

Ron Nielson wrote:
.. our trip started 5/29 and that's when the problem was noticed.

Thanks. This burn could have happened over time.

2oldman wrote:

Ron Nielson wrote:
2)Air conditioning and electric water heater not on since last year .

Not clear to me on when you think the burn happened.

The trailer has been plugged in to 110 since at least 11/15/2018, and then our trip started 5/29 and that's when the problem was noticed. That was our overnight stop in Denver. Until the Denver stop, no problems were noted.

I appreciate any and all replies and information. Keep them coming.

Ron Nielson wrote:
2)Air conditioning and electric water heater not on since last year .

Not clear to me on when you think the burn happened. But eliminating any loose connections, it must be an overload.

When you get this repaired, turn on the air and HW (or something else big) and feel that connection for heat. (or maybe an IR thermometer). Also a good idea to check pedestal connections too.

Any thoughts on the old transfer switch causing the problem?? I looked at the old switch but there's nothing out of the ordinary there, no burned wires, etc, If there was a loose connection inside the switch, I would think that there would be some sign of it there.

Some more information: 1) NONE of the wires on the bus are loose at all, it takes quite a bit of power to loosen them 2)Air conditioning and electric water heater not on since last year 3) Trailer has a hard wired surge guard and those screws, on both sides are tight 4) the screws on the new transfer switch connections were properly tightened. So I think most everything from pedestal to breaker box has been checked.

I can go to HD or Lowes and get a new buss, but not sure if there is much room for exposing new copper on the neutral side of wiring coming into the box. There needs to be some extra wiring remaining behind the box so that it can be pulled out to work on. I haven't pulled out the breaker box since I installed a new circuit in my storage area when trailer was new, so there may be at least a couple of inches. I hope so.
I can leave the breaker for the water heater turned off, but will probably need the a/c in the coming weeks.

Loose wire in RV electrical is a scandal. Holes in aluminum with set screws are NOT MEANT for fine stranded wire. The only exception is the rare example that has a permanent metal TANG permanently attached covering the screw entrance. I've got way too much experience in this area. There are Chinese terminal blocks for sale that do not have the tang. Avoid them when using fine stranded wire.

Heating of wires causes annealing making the copper as soft as mud. Tin plating disappears then oxygen turns the aluminum surface into aluminum oxide. Resistance rises like crazy.

The aluminum bar then needs to go to the aluminum recycler and the copper wire needs to be new-penny bright when it slips into a replacement aluminum.

To live dangerously is to poo-pooh the need to tighten all panel screws the moment a rig leaves the dealership. Then several months later do it again. Crushed wire is OK as long as the copper continuous to look like a brand new penny.

BTW the so-called anti-oxide slop which is 500% overpriced at hardware stores is a ripoff. It is pure cosmoline that in bulk costs $156.00 for a 55-dollar drum.

COSMOLINE by itself cannot remove oxide. You would be just as well-off smearing margarine onto the work. Silicone grease preserves better but the parts MUST start out brand new. The tin coating on the bus must not be damaged.

Squeeze set screw conductors demand THHN type wire with far fewer but much thicker strands of copper. This type of wire is FAR FAR more resistant to crushing and becoming loose when coupled to a set screw tinned aluminum buss.

My findings are a result of many years of experience and not guesswork or theory of parroting Chapter 9 section C sub section a)21 of some idiot code. If your panel catches fire after reading and ignoring this tip -- blame no one but yourself. This is exactly the reason why the NEC stays well away from RV electrical. The level of ignorance is utterly absurd.

You have experienced a very common problem with RVs.
2 things can cause your problem.
1: Screws not tight enough from the factory.
2: Copper under compression will crush over a period of time and create a loose connection.
Take either scenario, shake it down the road and you have a problem.
Yes the copper wires need to be cut back.
The buss bar can be cleaned with a small wire brush or replaced.
Buss bars are readily available from Home Depot & Lowes.

Richard

It is usually caused by the Main Neutral coming to the buss bar being loose. Hopefully, you have enough extra romex wiring behind the breaker box to pull fresh romex and cut off the burnt/hot wiring and install on a NEW Buss Bar. Do NOT use the original Neutral Buss bar. Overcurrent draw will not cause this to happen as long as the Neutral wires are secure and tight. Doug

Shortly after buying our 5er I opened up the breaker panel and fuse panel and checked wire connection tightness on all hot, neutral, ground, +12, and 12 ground points. Around half the screws were not properly tightened. Would probably have experienced the same as you over time.

Ron Nielson wrote:
All of my neutral wires are burned at the buss at the breaker box about 2". Does this tell you anything about where a loose neutral connection is likely to be? I have read that the burnt wires need to be cut back to good copper and the buss replaced. Is that because the burned wires and buss has a higher resistance than clean connections?

No it doesn't, other than right there at the busbar. It tells me you have, at some point, drawn too much current for too long. My RV won't handle a/c and water heater at the same time.

Yes, burned wires have higher resistance.