CW,
Back when I was small we had a similar problem with our main house
panel. My father and I smelled burning plastic when we wee in the
basement. He removed the front panel and we saw the plastic holding the
2 "phases" had melted.
Turns out we were just running too much continuos power through the
panel and had to upgrade.
We had an electrician replace the panel and upgrade the service.
Michelle
Seawulf wrote:
I have a home workshop and needed 220 V circuits for certain power
tools and 120 V circuits for lighting and receptacles.
Around the same time our central air conditioning system faded and
died. We live in southern California and do not have many really hot
days, so we decided to not repair it again and just let it be.
The 220V 50A circuit for the AC happened to terminate on one wall of
the shop. So, taking advantage of the situation, I decided to set up
a subpanel using the former AC circuit. I am not an electrician, but
have done other electrical work around the house, including wiring
attic fans, adding new outdoor circuits, etc.
I added the subpanel and ran a 220/20A line (10-2G NM-B cable) to the
tablesaw and bandsaw and two 120/20 A lines (12-2G NM-B cable) for new
receptacles. The saws are each rated at 220V/13A and are never run
concurrently, One of the 120V receptacles was dedicated to a dust
collector rated at 120V/18A or 220V 9A.
I have been running this setup for about two years with no apparent
problems. I recently removed the cover on the subpanel to check
something and found that the neutral wire for the line feeding the
dust collector, and connected to the neutral bar was charred for about
two inches from the bus. Most of the insulation had been burned off
along those two inches. Also, the black plastic around the neutral bus
shows signs of having melted around the perimeter of the neutral bus bar.
The circuit breaker on the dust collector line was still engaged. I
also tested the cb and found that it does shut off power to the circuit.
I checked the screw which held the charred wire to the neutral bus bar
and it was tight I also checked the screw holding the neutral wire
for the other 120V line, and it was also tight.
The 50A line from the main box to the workshop subpanel is Aluminum
(house is mid 70's vintage) and the Murray subpanel in the shop is
rated for both Al and Cu wire.
Does anyone have any ideas as to what the problem could be?
Thanks,
CW
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