Originally Posted By: bbadger This post was automatically imported from our archived forum.
We do not really know the cause, insulation failure
is the assumption.
This was recorded by a security camera for 1.5 minutes
before the power went out to the security equipment.
I did not see the tape but my friends say it was
shooting sparks, metal etc. out about 75' into the street.
There are houses about 100' away and the occupants
must have wet themselves if they saw it happening. 
Here is the generator we had to bring in, you can see
the houses.
The power company also had to replace the transformer
as the oil in it (oil keeps them cool) boiled over exposing
the coils leading to a short circuit which is what finally blew
the power companies 13,800 volt fuses.
Had the transformer not expired this would have kept
burning back like a wick on a fire cracker.
-- Bob Badger
Electrical Construction & Maintenance
Moderator at ECN
Originally Posted By: bbadger This post was automatically imported from our archived forum.
jtedesco wrote:
Bob:
Was there some relationship to 310.4 and 300.20?
I was not there but I am sure my friends would have noticed that.
jtedesco wrote:
If I can get a copy of the video I can burn it and post it
If it was possible I would already have it. 
jtedesco wrote:
Was the junction box rain tight?
Yes that would have been a NEMA 4 Galvanized, gasketed, screw cover box.
This service is virtually identical to 50 + other locations of this retailer.
The box is directly referenced in the job specifications along with the rest of the service conductor installation.
It might have been as simple as a foreign object in the raceway when the conductors where installed However that is pure speculation and I really do not know what caused the problem.
This installation had been up and running for a long time before it self destructed.
Heck for all we know the conduit took a bullet, it would not be the first time.
-- Bob Badger
Electrical Construction & Maintenance
Moderator at ECN
