ghad

now i know this will end up being something very simple but for the life of me im out of ideas.
i have ben called to a fault at a lighting retailer where a 100A CB protecting a set of 185mm sub mains about 70metres long keeps triping. after inspection it was aparent that it was just a bad connection at the private meter as one phase was almost completly burnt out and had started to melt the meter.
the meter and CB were replaced.

the new CB proceeded to triped later that day, and it came to my attention that the meter and CB were still getting very hot, so ...back to the drawing board for a good look.

Now this meter and CB is in a DB that houses 3 tenant meters and CB's and one community meter, a 3 phase chasis and CB. all are protected and isolated by 415A CB and MS respectively. none of the other 3 have a problem.

after testing continuity, polarity, current draw (at different times and conditions) and insulation resistance and found the results to be more than adequat, a closer visual insection found that the the internal wireing of this board was not uniform between phases so...

we replaced all the internal connections withe new cable and installed fuses to protect our meter.

we lost a phase the next day.

we have tried various other ideas and long shots but still we can not find a reson for the excessive heat being generated at this point.

an in depth testing of the shop itself is our next step any other ideas are more than welcome.

we have also tested connecting parts of both boards inc MS's and Chasis and have recorded the current on all circuits in the shop all seen normal.

please let me sleep
ghad

muttnik

Ask the holy spirit to help you. He knows.

randomkiller

Wow that was truly a well thought out educated responce. I'm sure the OP will be greatful.

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randomkiller

I would look over all the parts associated with the overheating from the original bad connection and see if some other part wasn't damaged by the heat.

__________________
A Veteran - whether active duty, retired, guard or reserve - is someone who, at one point in his life, wrote a blank check made payable to "The United States of America," for an amount of "up to and including my life."

"One Nation Under God"

muttnik

Bundle the neutral & the ungrounded conductors on the same side of the inclosure. (My people parish for a lack of knowledge)

MDShunk

You've done some good stuff, but I'd really like to see your DLRO and IR results. Those are the tests I'd think of first for a heating problem, rather than the tests you've done so far.

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muttnik

Hay random dog, what's that "heat inducing field" that is created when you run the conductors of the feeder up opisite sides of the panel?

76nemo

Give him a few more minutes, he's consulting his "Holy Spirit".

steelersman

yeah, especially considering that there is no such thing.

muttnik

In order to receive data from the HOLY SPIRIT, you must be prewired.