Breakers tripping? Getting hot? Check your neutrals.

[Wayward]

A safety check worth making..............

As I'd assume is the case for most Airstreams, the neutral wires for all AC circuits connect on to a common bus bar with small set screws (just like residential breaker panels). As I just found out, the neutral wire connections can loosen in our trailers. When they do, the poor connection will cause a voltage drop and/or arching. Then, the copper wire heats up, the breakers heat up, and a breaker trips.

Bottom line maintenance recommendation is, pull the cover over the breakers, check all the neutral connections and firmly re-tighten.

longer story.....

The first night into a long road trip, a hair dryer tripped a breaker. I opened the breaker panel and reset it. I remember it odd, that maybe it had been the main breaker - not the bathroom receptacle breaker.

A week later during the first hot evening, the air conditioner tripped off. It was indeed the main breaker that tripped, not the air conditioner breaker. So, I started looking around. The main breaker and the metal panel were hot to the touch.

I pulled the panel cover. The shore power neutral feed wire was loose and showed signs of heat - as did a couple of the branch circuit neutral wires. I trimmed the ends, cleaned the exposed wire and reconnected all neutrals. All is good now.

A search of the WWW turned up similar stories so this may be a problem common to RVs. I've never had this happen in a house.

It is definitely worth a check for this during maintenance.

(note: some internet posts I saw say to re-tighten the ground wire connections. While this too is good to check, grounds should not normally be carrying current.)

[richard5933]

This is quite common on automatic transfer switches. My theory is that the frequent clanking of the transfer switch slowly works the terminals loose.

On our first RV I learned that there are actually torque settings for these terminal screws. It was surprising how far from the spec the they were in my first coach. As I worked to tighten them all to spec I learned that it's not enough to just put a torque driver on them and check for the click - quite often there is a bit of corrosion holding the set screw in place which will fool the torque driver into thinking that there is adequate torque. But what's being measured is just the torque necessary to break the corrosion, not the torque being applied by the set screw to the wire conductor.

All the new equipment I installed, including the Victron and Progressive Dynamics equipment, also has torque settings on the terminal screws.

The way I check torque on these set screws during the annual maintenance is to loosen them slightly be hand and then use the torque driver to re-tighten.

A torque wrench is usually not going to be good for terminal screws since they are measuring foot-pounds. A torque driver measuring inch-pounds is what's needed, and I find a T-handled model makes quick work of it.

I've got one similar to this: https://www.amazon.com/ALEAPOW-Screw...s%2C335&sr=8-5

[SSquared]

Very good point. We detected a mystery burnt smell in our 2014 25FB and could not track it down. We eventually found brown/charred insulation on most of our neutral wires. We replaced those wires, and now re-tighten them every year or two.



I posted a picture of my damaged wires in a thread here, but I can't find that thread.


Thanks for bringing this up for the benefit of others.

[Wayward]

Originally Posted by richard5933

A torque driver measuring inch-pounds is what's needed, and I find a T-handled model makes quick work of it.

nice tool. thx

[TerraYacht]

"A search of the WWW turned up similar stories so this may be a problem common to RVs. I've never had this happen in a house."
There are similar issues in some house wiring. Some homes use aluminum wiring, often from a mains breaker to a remote panel, and the changing current makes the aluminum expand and contract which can loosen the screw clamp. Plus, the dissimilar metals contribute to the different rates of expansion and Corrosion also happens. I lost a phase in my home and using my infrared thermometer found that one phase was very loose!
I also recommend an infrared thermometer so you can occasionally scan the breaker box, look at wheels/hubs temperatures to hunt for issues like dragging brakes, etc.

[Wayward]

[QUOTE=TerraYacht;268 dissimilar metals contribute to the different rates of expansion and Corrosion also happens. .[/QUOTE]

True. I keep a tube of Ox-Gard around. I think it was originally made for aluminum wire connections. I use it on any and all types of electrical connections on the Airstream, vehicles, boat, house etc. Even on breakers and box connections.

https://www.lowes.com/pd/Gardner-Ben...mpound/4514334