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? The rest of the story: Trailer is a 2009 Arctic Fox 5th wheel. Only known electrical problem was probably 9 years ago plugging into a sloppy electrical pedestal at an Arkansas state park, and that burned the trailer's connector blade at the pedestal. Trailer is plugged into 120V power at the house all the time. We left KS and stopped overnight in Denver. Plugged into 120 and had power in the trailer for a few minutes, then no 120V power, so used 12V that night and went on to Ogden UT, plugged in no 120v power. Discovered that neither the 120V power nor generator power would come into the trailer, so figured that the transfer switch was bad. Changed out the transfer switch and then had 120V from both shore and generator. That's when I started smelling burning plastic smell in the breaker box. Can't say if they were burned before, but never a problem before this trip.

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.

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.

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

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

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.

Burned Neutral Wires at the Buss in the Breaker Box

MEXICOWANDERER
Explorer
Jun 03, 2019
TURN OFF all power THEN feel for a warm terminal :)

Sorry to be so grumpy in my prior post. There is only one correct answer to this and I have posted it numerous times and the response seems to be "HUH?"

Something that can kill you is slightly more inconvenient than something that merely breaks or doesn't work right.

The moment you get your 'new-to-you' RV home, grab a flat blade screwdriver go to the AC panel and 1 by 1 pull neutral wires and closely inspect copper wire ends. Shiny as a new penny is the rule.

If a wire end isn't shiny it's time for a replacement buss bar. Home Depot and others sell them.

Next, take several images of the buss before you disassemble. COUNT the number of wires.

Dip the shiny-as-a-new-penny in silicone grease then start inserting them into the newly installed buss bar

When you go to tighten the shiny-as-a-new-panny set screws, tighten the living scronche out of the set screws.

When all the neutrals are done, check the hot line voltage black wires. Every last one should be tighter than hell and it's it's common to hear a 'snap' as the screw loosens. As long as the screw has been loosened pull the wire out of the breaker and check for shiny-as-a-new-penny ends. These you can scrape shiny with a sharp utility blade. dip in silicone grease and then re-install.

After a hundred or so road miles, re-check all screws.

You will not be dealing with this issue again. Sleep tight.
Ductape
Explorer
Jun 03, 2019
Is it a 50 amp service?

If its not, it's loose connections = high resistance where the burn is. Resistant at location A does not cause a burn at location B. The problem is precisely where you see it.

A 50 amp service, if miswired at the source, can potentially overload the neutral. So long as it's correctly wired to 220v, the neutral carries only the DIFFERENCE between the two hot wire currents.

If the source outlet has both 50 amp sources at just 110v, the neutral will carry the SUM of the two hot wire currents. No outlet should be wired at 50 amp /110-120v but you hear occasional accounts of people who've encountered a "cheater" 50 amp plug.
2oldman
Explorer II
Jun 03, 2019
MEXICOWANDERER wrote:
Loose wire in RV electrical is a scandal. Holes in aluminum with set screws are NOT MEANT for fine stranded wire..
I've used Romex for inverter wiring for years. Not as much contact surface area, but no squashing either. My Cotek 48v inverter just died, but the 120v set-screw Romex was shiny and clean.. and I run air off it regularly. Just have to wiggle the heck out of it when installing to make sure it's really in there good.
dougrainer
Nomad
Jun 03, 2019
Your BUSS screws will appear tight because the BUSS got hot and seized some of the screws. If you have an Open/loose Neutral on a 50 amp RV, it will usually NOT burn or melt anything. It will supply 220 to the RV and burn out some appliances The Open on a 50 amp can be at the CG pedestal or on the Shore cord or at the Main electrical breaker panel. Doug
CA_Traveler
Explorer III
Jun 03, 2019
RVs vibrate and bounce down the road and connections become loose. All AC connections should be checked and tightened annually.
wa8yxm
Explorer III
Jun 03, 2019
BB_TX wrote:
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.

Ditto. I had issues with my A/C.. Poking around one of the wires moved (NOTE I do know how to poke around safely. REMOVE POWER FIRST (Unplug) well I got out ye old screwdriver and 3 1/2 turns later.. .Was happy

Decided it was a good time to take a tour-de-screws.

Now I tell folks many RVers have "A few screws loose".
I used to have a co-worker who fully agreed. but somehow I don't think we are talking about the same screws.

I also had a loose screw on the power inlet

And one camper I assisted had not one not two but SIX loose screws in his shore cord Outlet (The part that plugs into the RV).. Now in case you are wondering there are only six screws INSIDE that device (plus two more outside.. Those were tight)

We got him back in business.. But I'd have loved to be a witness to the chat he had when he got back to his dealer.. You see the Trailer was so new the sticker was still in the window. .I kid you not.
Ron_Nielson
Explorer
Jun 03, 2019
Latest update. I cut back the burned neutrals, cleaned the grounds and every breaker now has power and nothing is overheating after 3 hours or so. THe only remaining thing is that the A/C (air contitioning) unit will turn on, run for a few minutes, then shut off, but not restart. If I recycle the breaker,fool with the thermostat, it will again start briefly ad shut off. So the original problem and subject of my original message is win and a fix, thanks to all those who tok the time to share their thoughts. And it was really quite easy. Who knew that replacing the buss and cutting back the neutral wires would work so well.
MEXICOWANDERER
Explorer
Jun 03, 2019
Throughout Quicksilver I used marine duplex tinned twin wire.

The size No #6 uninsulated spade 12-10 gauge. This fits household receptacle screws.

Soldered onto the 10 gauge duplex wire

Meltable liner 1/4" shrink tubing.

Then smothered in dielectric grease and the grease was forced into the double contact slots until it oozed out.

When the spade terminals were slipped under the receptacle screws I tightened the scronch out of them. Bryant green dot 20-amp (hospital grade) pieces with nickel plated hardware.
larry_cad
Explorer II
Jun 04, 2019
Ductape wrote:
Is it a 50 amp service?

If its not, it's loose connections = high resistance where the burn is. Resistant at location A does not cause a burn at location B. The problem is precisely where you see it.

A 50 amp service, if miswired at the source, can potentially overload the neutral. So long as it's correctly wired to 220v, the neutral carries only the DIFFERENCE between the two hot wire currents.

If the source outlet has both 50 amp sources at just 110v, the neutral will carry the SUM of the two hot wire currents. No outlet should be wired at 50 amp /110-120v but you hear occasional accounts of people who've encountered a "cheater" 50 amp plug.

Sounds like you know what you are talking about! Good post.
larry_cad
Explorer II
Jun 04, 2019
dougrainer wrote:
Your BUSS screws will appear tight because the BUSS got hot and seized some of the screws. If you have an Open/loose Neutral on a 50 amp RV, it will usually NOT burn or melt anything. It will supply 220 to the RV and burn out some appliances The Open on a 50 amp can be at the CG pedestal or on the Shore cord or at the Main electrical breaker panel. Doug

Excellent post as usual from Doug.

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