This question keeps popping up on 2361 exam paper and instructors and sparks all seem baffled, wonder if anyone can shed any light, Q Fuses should be fitted in both conductorsdof a single phase circuit in a damp situations b high voltage circuits c direct current circuits d non earthed circuits
can find no mention of this in OSG or regs ( not saying it isnt there ) or text books any hlp much appreciated
Wonder how you can have single phase direct current?
I believe the answer they are after is (c), though in reality it's the wrong solution for any of these.
I'd be very inclined to go with a non-earthed supply as the answer, but a mains supply that isn't earthed on the domestic side of the service head isn't really a proper supply in my opinion.
If you look at most step down transformers on the grid, they have a breaker link on all conductors, so this is why I'd say it's a non-earthed circuit that should have a breaker on each conductor.
d is the only situation here where a fuse is even permitted in both conductors (see 131-13, 437-03-03, 530-01-02). However, I suspect there's some wording fault in the question.
There often seems to be a couple of badly worded questions; anyone who is that marginal on the exam probably deserves to fail as the pass mark isn't that high anyway. I wouldn't worry too much about it.
... and it's not OT...
Once fitted a 12v pmr raido into a 24v caterpillar thing with correctly rated voltage converter, Fused on the pos side as usual. Next day got a call, radio and wiring had burnt out... Stupid yanks had fitted master battery cut-out switch on the neg-earth wire, operator gets in turns ign key without turning on master switch. were did the starter motor now find its earth... ;-(
On 8 Jun 2004 21:23:14 GMT, snipped-for-privacy@cucumber.demon.co.uk (Andrew Gabriel) strung together this:
I'd go for that one too.
When I was an apprentice we went through some of the old exam papers and most of the questions were badly worded and depending which way you read them usually 2 or 3 of the answers would be the correct one! Obviously written in the same way as the regs, worded to sound extremely technical and spot on specific and definitive but in actuallity utterly useless and totally vague.
snipped-for-privacy@cucumber.demon.co.uk (Andrew Gabriel) wrote in news:ca5ao2$qqb$ snipped-for-privacy@new-usenet.uk.sun.com:
I went through a lot of pain in the sixties (or was it seventies) with double fused circuits.
I would have thought it was obviously lethal, and eventually lashings of time and money was spent on removing the neutral fuse on squillions of units.
I think they're referring to the outputs of isolating transformers, which are floating.
But I've been known to be wrong....
mike
Most of the very first electrical installations had a fuse on both conductors because they couldn't rely on the earth bonding through the old pipes with the wrapped wire around them. I've heard of the earth wrap blowing a hole through the lead pipe if the circuits got shorted over to earth.
Many years ago, I re-wired my parent's house which had DP fusing, and there wasn't an earth in sight. Apart from one for the radio, that is.
Hee Hee !!! You've been in my grannies house as well then ? She had that set up for years so she could hear the news. :-))
In message , Lurch writes
Agreed.
I found with the apparently weirdly worded questions that when you found the right regulation, it was worded in the same way.
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