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Well that would be a load of 4.58A, so in theory would not blow fuses but would be a hell of a drain on finances! However Live to neutral faults are very rare in T+E installations, A connected load would be much more likely, being that its in the hallway, this would be the most likely place for a spur which could be anywhere in the house! Also, since this is a likely load connected I would be very careful meggering it further as you could end up buying some form of domestic appliance! That would be far more of a pain then the fault :wink5:
My domestic experience only extends to testing/repairs and fault finding and I have yet to find a genuine L-N fault!
 
Cables from upstairs to downstairs can be damaged if they pass through the stair treads and are constantly trodden on, also are you sure that there is not something in the cupboard under the stairs as it is an easy place to spur from, tap in to get a light, etc.
1kW appliance sounds unlikely in that location but could be possible, or a failed accessory.
 
I've located the fault. A cable run just under the floor boards had worn. Replaced cable and all fine now on the live neutral ir front. However I've now lost continuity between the two ends of the ring. Going through everything I've done now but everything is connected correctly.

I've got a reading of 0.31ohms between neutral and earth (evetything is disconnected from cu). With this being an old installation this could be a bare earth touching a back box or neutral leg, is that a correct?

I'm going to connect a fly lead to each leg and go round to see if i can see where the live i as lost.

Pain in the arse these fault finding missions aren't they?

Ps all the meggering has been done at 250v incase of connected appliances ive missed.
 
Again an update for those who are interested.

The faults I found were, loose neutrals in a kitchen socket, a poor (very poor in fact) connection for the boiler - were loose strands were hanging out everywhere (British Gas so called fitters for you :innocent: ) and a broken cable under the floorboards were a wardrobe had recently been moved. All fixed and working.

But the biggest thing I found, which once realised made a lot of sense to my test readings, was that the sockets which were fed into the same 30A fuse labelled "Socket Ring Main" is actually two radial circuits. So I've de-rated the fuse to 15 Amp and moved one of the circuits to a spare fuse rating that at 15 amp as well as a temporary measure. I've notified my customer that if she uses too many appliances at once she may blow the fuse and that she really needs a re-wire and new CU. As expected she doesn't want the expense and mess of decorating. So I've said she really needs the circuits to be protected by a 20 amp fuse and have suggested replacing the re-wirable fuses with the plugin mcb's (its a wylex board). Because I found a short between earth/neutral I can't put rcbo's in so wondered if putting an rcd before the board would still work, although I think the short is happening between the installation and the building.

I suppose not finding that the sockets were if fact radials is due to a lack of experience and will be learnt from, not to take other peoples notation as gospel is one of them.

Thank to all that helped and allowed me to have a Sunday off for once :)
 
Glad you sorted it mate, it's a good feeling in the end. An upfront RCD will still trip.
 
It does, especially when you flick the switch and plug your tester in and you don't hear snap crackle pop and get the results you want :)

I thought it would do but thought I'd look into the idea. I've told her that she really needs a new CU, which in turn will mean she needs a rewire (mainly because of the N+E fault and the IR between L+N was 8mohms. Must be puzzling for her though because the system has worked for 40 years. I've told her to go and get a second opinion if she needs but at least give me a chance to quote :). She has taken me up on the suggestion of recplacing the re-wirables with plugin mcb's.
 
She has taken me up on the suggestion of recplacing the re-wirables with plugin mcb's.
Some people are even reluctant to do that. However I have pointed out the benefits even even just doing the lighting circuits so they're not trying to cram a nail in the carrier with a match between their teeth...
 
why not find the 2 ends of the radials and link them to form a ring,
then find the e/n fault and fix it
(btw what size cable are the radials ? some are 4.0 mill)
 
I've suggested that but she doesn't want to redecorate. Plus that would then be notifiable work and would need to comply, which it wouldn't because there is no rcd.

I've tried to find the E+N fault at each point and can't locate it. It is also in the lighting circuit. She doesn't want me ruining her house basically :).

It's 2.5mm^2 cable as well.
 
It does, especially when you flick the switch and plug your tester in and you don't hear snap crackle pop and get the results you want :)

I thought it would do but thought I'd look into the idea. I've told her that she really needs a new CU, which in turn will mean she needs a rewire (mainly because of the N+E fault and the IR between L+N was 8mohms. Must be puzzling for her though because the system has worked for 40 years. I've told her to go and get a second opinion if she needs but at least give me a chance to quote :). She has taken me up on the suggestion of recplacing the re-wirables with plugin mcb's.

Just out of interest why does a l-n ir reading of 8meg ohms make you think it needs a rewire?
Its still well within the allowable although low it still is acceptable.
Would it not be better to suggest finding the n-e fault and just a fuse board upgrade
 
I've tried doing the test on both 500 VDC and 250 VDC, where both gave me a 0.00mohms reading @ 0.8VDC (which has puzzled me).
Just for information -

This is because the meter has detected the very low reading ( 54Ω in this case ) and stopped the test at 0.8V rather than go up to 250V or 500V which may damage equipment.



Also, you haven't mentioned end to end continuity testing of the conductors.

This should be the first test on a Ring and would have told you right away that it wasn't a ring - because it never was or that it was broken.
 
Just for information -

This is because the meter has detected the very low reading ( 54Ω in this case ) and stopped the test at 0.8V rather than go up to 250V or 500V which may damage equipment.



Also, you haven't mentioned end to end continuity testing of the conductors.

This should be the first test on a Ring and would have told you right away that it wasn't a ring - because it never was or that it was broken.


Thank you for the info. Like I said, lessons obviously learnt and all down to experience.
 
bf2k--
take all of the sockets off of the faulty radial, and part the conductors--(its an old 70,s built, so there can,t be many sockets),
in the existing d/b, disonnect the l/n/e of that radial circuit, then test each leg,starting from the outgoing 2.5 twe then each loop to the last one, the final socket with only one cable
if you find some kind of fault on a leg trace it
 

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