Now that my rewire is about there, my thoughts have returned to my elusive earth fault on the downstairs (radial) lighting circuit.

There is a distinct, though slight,  current at present flowing to earth regardless of whether lights are switched off or on.  ??? It gives you a definite tingle if you touch it - don't ask how I know........and lights up  my neon screwdriver - and I don't want to start any more arguments about that one either.......

This bothers me as I assume that whilst this problem may be caused by impedence it may also be caused by the earth wire cutting into the positive somewhere.  The other circuits don't do this, thankfully.

I have bought a multimeter but the most useful instruction which came with it with it is how to put the battery in  - the instructions aren't detailed whatsoever - along the lines of  'Touch the electrodes to the component you wish to test.'  Great.

What sort of current is acceptable?

Also, can anyone suggest a test procedure - is it a case of disconnecting the supply cable section by section until the problem goes away?

I have tried to interest a professional electrican in doing a periodic inspection, but, reasonably,  he doesn't want to come and test until the plastering is done and a new ceiling up in the dining room as he says we may produce further faults. I can see his point, but I know that I have THIS fault, and would rather sort it out before the floorboards go back down - it will never be quicker to sort out than now.....  

Thanks

JohnD

thats an idea TT, i think there probrably isnt a county without a spark member in it, somone can go ava look .....and then tell us if the wiring is bad, if it is then everyone must accept part p.

john the fate of the whole....well no one really
rests on your shoulders with your earth problem

ss

Sorry - meant induction, not impedence.

Insulation resistance test - is this a megger test?  How do I do one?

Thanks

JohnD

Right, that seems beyond me then!  

Will just try to find out manually which section of the supply causes the fault.

Thanks L.Spark

JohnD

Don't you ever sleep?!!

in theory the earth fault loop has a complex impedance when considered at mains frequency

in practice this is always approximated by a resistance. whilst not a perfect way of doing things this seems accurate enough for the perpose.

[quote author=L.Spark  link=1109720157/0#9 date=1109769562]Nice to know you're not completely out of it   [/quote]

Well I do admit that when I was doing my OND/HNC I didn't take a whole lot of notice of the Tesla experiments and that heavy electrical stuff, it wasn't my bag because I was more into the electronics low voltage/high frequency stuff.

But I took enough in to remember over the years I guess. We had a fantastic teacher at college, an older guy who must've been pushing up the daisies for some time now.

Hmm, I remember Southampton Tech showing us this wonderful piece of equipment - an analogue computer. That was in the days long before before PC's and digital computers were invented - to make the analogue computer do something you twiddled a knob!

HM

Thanks for asking!

Couldn't find fault with my neon screwdriver (no, I don't want to start that debate again ,  so simply replaced all three lengths of feed cable to be on the safe side.

All floorboards were still up and a ceiling down, so it didn't take long.

All now seems o.k. - there was a very, very slight glow, possibly due to induction - a length of wire straight off the reel did the same - but nowhere near the same 'glow' as before.

I am happy now to wait until the installation can be professionally inspected.

Thanks to all who responded

JohnD