Smoking Circuit Breaker

[Blaster 84]

The other night I noticed a hot electrical smell, similar to hot bakalight. I was unable to locate the source before it dissipated.
When we came back to the RV from playing tourist last night we found the AC breaker tripped. I reset it. After running the AC for awhile the hot smell returned. I pulled the AC breaker and it was very warm. I don't know if this is normal or not.
Thinking that it might be a breaker going bad I replaced it this AM with a new one. Running the AC with the new breaker the smell returned and now I am getting some smoke coming from the breaker where it makes contact with the central bar.
I did notice that the breaker is a 20 amp breaker, but the label on the breaker box is 15 amp.
I would appreciate any input on what to do next.

[wmtire]

Smoke from your electrical distribution panel is not good.

Most A/C circuit breakers in my experience on full size TT/5'vers are going to be 20 amps. I do know that the illustration sheet sometimes doesn't line up correctly for the breakers in the panel.

The circuit breaker you replaced, did you notice if the connection was burned on the backside where it attaches to the bus bar. If so, it could have actually melted the bus bar somewhat, and your new circuit breaker is arcing now there too.

Something is definitely not right, and needs to be corrected.

[5picker]

This is going to be one of those that's hard for us to give advice without being there.
We can speculate but in the end, that's all it is, a wild guess.

As mentioned, if you have smoke/smell coming from your breaker box, you need to get it looked at by a qualified person immediately.

[TitanMike]

I had this happen on a residential power panel once. The original breaker was apparently loose where it connected to the bus bar and it eventually burnt a spot on the bar.

I removed the breaker, taped up the shaft of a flat blade screwdriver and used the exposed tip to scrape the burnt area back to pretty bare metal. I then swapped positions, putting the replacement high amperage breaker (20 amp) in a 15 amp position that supplied power to a circuit I knew was little used (a yard light). I put the 15 amp breaker in the position where I had removed the old breaker. Before installing it I pushed the clip prongs a little closer together.

[Blaster 84]

Thanks for the replys. The contact points on the buss bar good good. No sign if arcing. Putting the new breaker in I had to really push hard to get it in so I'm confident it's making good contact. However when I get back to the RV I will try switching breakers around. It may be somewhat of a challenge as this duel breaker where two are put into the space of one

[mwdilday]

Are you sure the smell is coming from the panel? If the smell is from the A/C due to an issue then it could overload the breaker causing it to heat up. It is normal for a breaker to heat up when at or just above capacity.

[TitanMike]

Originally Posted by Blaster 84

Thanks for the replys. The contact points on the buss bar good good. No sign if arcing. Putting the new breaker in I had to really push hard to get it in so I'm confident it's making good contact. However when I get back to the RV I will try switching breakers around. It may be somewhat of a challenge as this duel breaker where two are put into the space of one

It may have just been a bad breaker. After all, they are mass produced and even the very best have a small percentage rate of failure.

If it was tight on the buss bar and the screw holding the wire in place is snug, I doubt it would be of any benefit to move the breaker.

Just keep an eye on the new breaker and see it it begins to heat up abnormally. Remember though, low voltage can cause motor driven devices to draw more current than normal. Might be a good idea to check the voltage at the panel when the A/C is running on high. If it's low then the current may be real close to the breaker's limit but not enough to trip it. Just enough to make it get hot and smoke.

[Blaster 84]

I moved the breaker to a different location, one that had not previously used. I turned on the 15 amp for 1 hour and no problem. I turned on the 20 amp side and ran the AC, after 30 minutes I get a strong burning smell I mentioned in my original post. I didn't let it run long enough so it would start smoking as before.
I do have a Progressive energy management system installed and a meter on one of my receptacles indicates 120 volts.
I suppose it is possible that I purchased a bad breaker.

[TitanMike]

Originally Posted by Blaster 84

I moved the breaker to a different location, one that had not previously used. I turned on the 15 amp for 1 hour and no problem. I turned on the 20 amp side and ran the AC, after 30 minutes I get a strong burning smell I mentioned in my original post. I didn't let it run long enough so it would start smoking as before.
I do have a Progressive energy management system installed and a meter on one of my receptacles indicates 120 volts.
I suppose it is possible that I purchased a bad breaker.

I'd see if you could lay your hands on an AC Ammeter, one that clamps around the wire going to the 20 amp circuit.

It's possible that one breaker is bad but unlikely that a new one would be bad unless you have incredibly bad luck

Before investing any more $$ see what the actual current draw is and address that first. Could well be an issue with the A/C unit, starting circuit, or motor.

[Macrosill]

Check your neutral bus bar. Make sure the connections are tight.

[Blaster 84]

If the AC is pulling too much wouldn't that throw the breaker?
All contacts are tight.
I'll see if I can locate an clamp type amp meter tomorrow.

[TitanMike]

Originally Posted by Blaster 84

If the AC is pulling too much wouldn't that throw the breaker?
All contacts are tight.
I'll see if I can locate an clamp type amp meter tomorrow.

It would be logical that the breaker would trip but what if the A/C unit is drawing the maximum current that can flow without tripping the breaker. That could create heat and the burning smell.

Normally a circuit with a motor in it will draw a lot of current initially, when the motor starts, and then the current will drop to a fraction of the starting current.

Don't know what's happening in your case but just trying to work possibilities in my head. Find out what kind of current your have first. Start with the basics.

[Bama Rambler]

Have you checked the main breaker stabs? It could be that instead of the new breaker. It could be loose enough to heat up and not trip.

[Blaster 84]

Update-
I ran just the blower motor this AM with no detrimental effect. So it is probably the AC. It would take a week to get a new one. Since the weather has cooled down here and we are going to head home next week anyway, we decided to put off further analysis until we get home.
Thanks for everyone 's input.

[Blaster 84]

Up update-
As we were preparing for departure this AM the smell and smoke return, and the AC breaker was off. I pulled the breakers out one by one looking for the source of smoke.
There are three screws on the bus bar securing it to the cabinet and I presume some electrical connection behind it. All three were loose. I was able to tighten two of them. The third would not tighten, threads stripped or deformed from heat. I have not had a problem seance. Efficiently I have arcing going on behind the panel and it was melting the plastic case and it was coincidental with using the AC.
Having a hot circuit breaker may have been normal. I don't make a habit of pulling circuit breakers and feeling them.
Now I have to determine if tightening the two screws is sufficient, or I need a new box.
Thanks again for the help.

[TitanMike]

Originally Posted by Blaster 84

Up update-
As we were preparing for departure this AM the smell and smoke return, and the AC breaker was off. I pulled the breakers out one by one looking for the source of smoke.
There are three screws on the bus bar securing it to the cabinet and I presume some electrical connection behind it. All three were loose. I was able to tighten two of them. The third would not tighten, threads stripped or deformed from heat. I have not had a problem seance. Efficiently I have arcing going on behind the panel and it was melting the plastic case and it was coincidental with using the AC.
Having a hot circuit breaker may have been normal. I don't make a habit of pulling circuit breakers and feeling them.
Now I have to determine if tightening the two screws is sufficient, or I need a new box.
Thanks again for the help.

You have a problem that needs attention NOW. If you have "arcing" behind the Converter you have a fire that just hasn't broken out yet.

If it were mine I'd have that Converter out of it's mounting place and all wiring coming into it would be inspected. That heat is coming from somewhere and if it's enough to melt or deform plastic it is enough to be a SERIOUS problem. The fact it's smoking and stinking is your only warning.

I don't mean to overly alarm you but this needs attention now and from someone who knows electricity and wiring.

[Blaster 84]

I appreciate your concern Mike. I did remove the breaker box out of the cabinet and inspected everything visible. It appears the smoke came from melting plastic behind buss bar, but no visible damage on the back side.
Next week I will be consulting the manufacturer and the RV service I use.

[TitanMike]

Originally Posted by Blaster 84

I appreciate your concern Mike. I did remove the breaker box out of the cabinet and inspected everything visible. It appears the smoke came from melting plastic behind buss bar, but no visible damage on the back side.
Next week I will be consulting the manufacturer and the RV service I use.

If the buss bar is heating up that's an indication that something is loose. Merely tightening it without cleaning the connections can often lead to a return of the problem. Heat causes more resistance to be created due to "corrosion/burning" which creates more heat.

I know it sounds like a PITA but to me a proper repair would be either replacement or total disassembly, cleaning, and reassembly.

Also, something as simple as "connection grease" which is a conductive compound that enhances the electrical connection and prevents corrosion can be a big benefit. You just have to pick the right compound, copper based for copper connections and aluminum based for aluminum.

Here'a a sample of one Copper based product and it's only $2.50 a tube.



If's sold by Georgia Copper and is a great product to protect the main connections to buss bars and at the back of the electrical entrance to a TT/MH.

Electricians use the Aluminum based stuff when connecting the main power feed to your electrical panel and it's also used on high current cable ends when they are crimped.

[Blaster 84]

Thank you Mike. That's a good idea. I'll consult with the manufacturer next week and I'll let everyone know I find out.