My pool pump stopped working. Power to the subpanel but not to the pump.
Pulled the breakers, Tested good. Noticed carbon deposit near block where
one of the hot lines connects. Removed the bakelite plate and the 2 hot
blocks. One was very clean after 30 years of use; the other had carbon
around and behind. The block is 2 pieces: literally a block and set screw
that attaches to the hot line and a "L" shaped bracket [where the breaker
fits] that sits under the block, held tight by a screw through the bakelite
plate. The prongs on the "L" shaped bracket looked fine. I separated the
block from the bracket and there was lots of carbon. I scraped off, cleaned
up [but nothing special], reassembeld tightly. Put everything back together
and all is working now.
My question is: should I have doen anything special to make sure I have an
optimal connection so this does not recur? Would an electrican have tried
to "mate" these surfaces or used a special cleaner?
Thank you for any comment.
The subpanel is in a shed and not directly exposed to the elements.
Exterior and interior are clean, no corrosion. A replacement subpanel is
cheap enough but would take me longer to rewire so I chose to try the
repair. If it fails again, I'll source a new subpanel.
Thanks to all responders.
*Sometimes a little sandpaper is all that is needed to get everything clean.
I am wondering what caused the problem. Was the screw terminal loose? That
would cause arcing which would explain the carbon.
One thought just in case...is the feeder Cu or Al? If Al, need to use
anti-oxidant on the connections. Wouldn't hurt to redo the other even
if still clean.
If there was any signs of pitting or other corrosion other than a
surface coating, it's possible there may be service parts available.
Then again, depending on the rating and the manufacturer, they may be as
much or nearly so as a new box.
I see no need to replace a good box for just a cleanup of a contact,
however. There are outside boxes on the farm here that are 50-60 yo
that are still just fine...of course it's moderately dry here as opposed
to areas farther east.
A relatively fine grit emery paper is the ideal tool for that; be sure
to remove all debris after.
The stores have grey paste, for aluminum contacts.
I'm not sure if I advise it, one time I used it
on .250 push in terminals, and it ate the teminals
away. Not good.
There has to be an approved coating, but I'm not sure
what it is.
Years ago, a friend had strange electrical flickers
in his house. I had a look, and find that the power
feed (through a 100 amp double pole breaker) was not
right. Had to pry the breaker out, and sand the bus
bars where the breaker clipped on. I may have used
some kind of protectant, but can't remember.
For automotive use, heavy water proof grease works
nicely to protect the wires.
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