Adrian - The research I have conducted states that it isn’t too unusual to find this setup. I am not a professional so I won’t be investigating anything any further. Suffice to say the work I carried out, with the advice heeded from this forum, has resulted in a satisfactory and safe job.
Advice on this one guys please....
- Thread starter pp7822
- Start date
Adrian - The research I have conducted states that it isn’t too unusual to find this setup. I am not a professional so I won’t be investigating anything any further. Suffice to say the work I carried out, with the advice heeded from this forum, has resulted in a satisfactory and safe job.
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Anything can (or should!) withstand an IR test if one undertake the test from L+N to E.
Kind Regards, John
E
EddieM
I thought I read somewhere that a high voltage IR test can fry the USB electronics.?
Such a high voltage test has the potential to fry almost anything electronic (including dimmers etc.), if the test is conducted between the L&N conductors, thereby subjecting anything connected to the supply to the high test voltage. However, if L&N are joined together, and the IR test conducted between them and earth, then none of the test voltage should appear across whatever is connected (to L and N).
Kind Regards, John
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EddieM
I see, that makes sense.
I’ve zapped a few sockets with USB outlets with my IR tester with no ill effects.
Zapped what - L to N?
Even if it were, as I wrote high voltages only 'have to potential' do damage electronic things, and certainly don't always (perhaps not often) do so. Of course, potentially damaging the load is not the only issue - even when there are 'no ill effects' the IR measurement may well be appreciably affected, possibly markedly so.
Kind Regards, John
Yeah I’ve zapped L>N and L>E. It always gives a really low reading which is when I normally remember to disconnect them. 
I guess that conforms both the points I made - that L-N IR testing of such things doesn't necessarily damage such things, but that it is likely to 'markedly affect' the IR measurement seen!Yeah I’ve zapped L>N and L>E. It always gives a really low reading which is when I normally remember to disconnect them.
Kind Regards, John
FWIW my preference where there are two earth terminals on a socket is to put the two CPCs of the ring in separate terminals. That way, should a terminal work loose for any reason, the socket is still earthed even if the loop impedance will be somewhat higher. And it should get picked up on the next test - yes I test when I do work on the house electrics, and the rental properties get tests on change of tenant (and now, every 5 years).
Wow. Big assumption it will be tested!
I’m sure most places go 20 years without test
I’m sure most places go 20 years without test
Out of curiosity:
Looking at first picture i see 2 twin & earth wires going into the box.
Now, lets disregard live and neutral wires for what i'm asking.
One of the earth goes into the back box, then from there to the socket.
The other earth from the second twin & earth goes to the socket.
I have always seen the 2 earth from twin & earth connected to the socket and a third independent earth wire connected from the socket to the back box.
Is it acceptable as all earth is connected or there's some rules about this?
Looking at first picture i see 2 twin & earth wires going into the box.
Now, lets disregard live and neutral wires for what i'm asking.
One of the earth goes into the back box, then from there to the socket.
The other earth from the second twin & earth goes to the socket.
I have always seen the 2 earth from twin & earth connected to the socket and a third independent earth wire connected from the socket to the back box.
Is it acceptable as all earth is connected or there's some rules about this?
It is not a requirement to earth the back box. It is not an exposed-conductive-part.
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