Pete C. wrote:
Ian Malcolm wrote:
Iggy is considering working on the feed to his panel. We presume there
is a supply company fuse somewhere upstream but with Iggy, who can tell?


The fuse will be on the primary side of the distribution transformer and
is unlikely to blow if someone shorts one phase in their panel.

I'd expect the screwdriver, wrench or whatever to loose a fair bit off
the end then. Over here, we tend to have a *LOT* of households tapped
off each phase in turn of a three phase 240 V main. Due to the
extremely large current available, the feed to the meter comes through
an electricity company owned fuse, (or one per phase). Wireing up to
that fuse is NOT MY PROBLEM and after the meter is my responsibility. I
can pull that fuse if I need to work on the board, but have to get the
company out to check and reseal it on reconnection.


The construction details of all the code approved distribution panels in
the US take care of pretty much all the clearance issues.

And so it is with modern consumer units (thats what they call the
domestic ones with an integrated masin disconnect) over here.

With that in mind, does the fact that he's not likely to get
himself accross more than 120 V (though there is 240 V in there phase to
phase) make a lot of difference compared to 240 V panels over here.


Not a lot, only a small difference in the insulation necessary and any
decent electrical tape will be good for either.

Yes.



As
I said, vaporised copper & steel is not your friend. If one of the
screws shears and the driver slips, what happens next?


Can't happen in the US panelboards (from the last few decades at least),
the top of the Allen setscrew is generally close to flush with the top
of the connector block. It's also a decent size Allen setscrew, like
5/16" or possibly 3/8" so it's unlikely to strip internally either.

Good to know.

I've stripped out some real horrors over here. Pre war as far as I
could tell. Mahogony case with a mica window, two brass buss bars with
*thumbscrews* !!! and either side more thumbscrews and terminals for the
other end of the fuse wires. It had fuses in both live and neutral, (I
belive there used to be a DC system that was symmetrical about ground in
the area) and it had a couple of its set of little sprung flags left
that would pop out into the window when the fuse wire broke to indicate
which circuit was blown. The disconnect feeding that was a knife switch
which had a metal guard that wasn't grounded. The whole lot was wired
with cotton covered wire with totally powdery hard rubber insulation.
Not supposed to still be in service, but the previous owner had been
there since the place had been built back in the 30's. She used to plug
her iron in the kitchen light socket. Between that and a three phase
panel and sub panel in our workshop where some idiot had ripped out the
conduit which had been the sub panel ground and rewired it without one,
and the bare unlabelled buss bars inside, there are plenty of ways to
get in trouble over here.

The government has finally brought in a law that all domestic
installations must be inspected by an approved contractor (who will
normally insist in being paid to do the work as well as to inspect) and
changed the wiring colours so as to keep the DIYers honest. Looking at
some of the stuff I've seen, I guess its probably for the best, but
those of us DIYers who were working to code are slightly ****ed off
because previously, unless you were very lucky, you'd wind up having to
sort stuff out that wasn't up to spec if you had occasion to open up
any part of an installation that had passed a full inspection, or even
find remedial work you had paied for 10 years ago hadn't been completed.


Nearly everyone was concentrating on insulating the tool, not on
protecting Iggy. IMHO he needs to do *BOTH* so that if something goes
wrong, he's got a chance to come back and tell us how he *nearly* had a
bad accident, rather than the alternative.


We must presume that he has enough sense to not try this while standing
barefoot in a puddle, after all he hasn't killed himself with his RPC or
welder yet.

Pete C.
Well he's gone and done it without running into any trouble, thankfully.

Its been an interesting discussion. Thank you.

--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
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