QuestionDear Larry,
On a recent camping trip in our 1989 class C Glendale we awoke to the smell of electrical fire. I quickly noted it was the main breaker, which is a split Seimens 30/20 amp. The 30 appears to be the main,while the 20 runs the a/c. The a/c had been running fine for about 3 hours and there does not appear to be any problem with it. The 20 amp side of the breaker appears to be weak as the switch double clicks. In the morning I was unable to replace this breaker with the same type so I bought a 30amp breaker and an left the a/c disconnected. Everything worked fine except I noted the bus bar on the breaker box had eroded (burned), so I moved it over 1 spot in the box.
My question is this, can I just put a single 20 amp breaker in the box for a/c, as there is room or do I need to use the same type of 30/20 breaker. A couple of notes. My coach battery was shot at the time of the incident and was replaced in the morning as I thought this may have lent to the problem. Also we needed to use two 30amp extension cords to reach the outlet and I wonder if this may have added to the problem. Also I thought the breaker should have tripped prior to burning on the bar and on closer inspection I noted the other breakers are getting loose, possibly from age. Probably worth changing them too.
AnswerHi Bill:
I see no problem, with the replacement breakers, being exchanged as you did. You still have the 30 amp main for overload protection, and the 20 amp for a/c protection.
The cause of the burnt breakers, was primarly due to resistance where the breaker locks onto the bus bar. The breakers all should be checked to be sure they fit snug onto the bus bar. If not, depending on type, they can sometimes be squeezed together, to form a tighter grip onto bus bar. Over time, corrosion builds up, causing resistance, and resistance causes heat. The heat build up is what lead to the breaker over heating.
You should lightly sand the corroded area on bus bar, to remove any accumulation of dust or debris. Then lightly coat the bar with the gray, electrical corrosion paste. This is a graphite mixture, assures good connection properties, and resist further corrosion. Can be purchased at most home supply stores or any commercial electrical supplier.
The two extension cords should have been ok to use. The only problem is that they may cause a fair voltage drop, due to longer runs. I've had to use these before as well. As long as the other breakers fit snug on bus bar, should be ok. As far as the coach battery going bad, I think this was just coincidental. Ive had the very same experience with my coach battery dying when I started to leave a campground once, also. Could not find any reason for failure, except perhaps age and heat.
If I can be of further assistance, please do not hesitate to contact me.
Regards, Larry
