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Discuss Flat with no earth at sockets in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

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peterpan

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I've been sent to inspect the wiring at a flat, it's a solid concrete flat with conduit (about 16mm) buried. So trying to pull singles through the old conduit is near impossible. Also none of the sockets have an earth. The flat is on a 2nd floor. What's your views? Idealy a rewire is needed, would a twin rcd be board be acceptable?
 
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Tiger

  • Thread Starter Thread Starter
  • #2
I've been sent to inspect the wiring at a flat, it's a solid concrete flat with conduit (about 16mm) buried. So trying to pull singles through the old conduit is near impossible. Also none of the sockets have an earth. The flat is on a 2nd floor. What's your views? Idealy a rewire is needed, would a twin rcd be board be acceptable?

Not idealy, It's an absolute MUST

No earths at the sockets, it wants condeming:eek:
 
S

Spudnik

  • Thread Starter Thread Starter
  • #3
In days of old the steel conduit was used as the cpc, which is why there isnt one present.

You will probably find the same with the lighting.

Although it is still allowed to use this method, you need to carry out the testing ensure that is adequate and still intact.
 
P

peterpan

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  • #4
Sorry was meant to mention the conduit is used as a CPC. But they haven't earthed from the back box into the socket.

If I was to earth every socket/back box, upgrade the DB. Also earth all the lights to, this should be enough to bring it up to todays regs? Obivously earthing main water/gas
 
G

Guest123

  • Thread Starter Thread Starter
  • #5
Hi.

I dont know if I'd be happy with leaving it on the steel conduit as earth. If you do then I would say you need to go overboard with your testing to ensure there is cpc continuity at every socket outlet lighting point etc. An r2 test with a long flying lead between the earth bar of your cu and earth terminal of every socket and light switch/fitting etc would be advisable aswell as your R1+R2.

Also make sure your earth fault loop is low enough to comply and to ensure that your disconnection times are met.

With old steel conduit the joints at boxes couplers can corrode over time and cause high resistance joints which may impair the safety of the installation.

Cheers.
 
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Spudnik

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  • #6
Agree with lenny (nice avatar by the way:D).

You really do have to make sure all your results are well within the limits.

But to be honest, cant say id be happy leaving the conduit as CPC especially considering the age of the installation.

You need to discuss with the client a possible rewire and the costs involved.
 

andyb

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Arms
Esteemed
If you run an earth into the conduit, how do you test it?
To get a true reading for r2 you would have to take every socket off the wall and disconnect the fly lead from the socket to the back box, otherwise when you test across the two ends at the board you would still get a reading even if the earth was broken somewhere.
At least with the conduit as your earth you can prove continuity by the method described by lennytheloon above.
I know using the conduit as your earth is out of favour nowadays, but it’s a lot easier to test.
 
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Guest123

  • Thread Starter Thread Starter
  • #8
Hey.

The other thing that has occured to me is that if you do change the c.u then how are you going to reconnect all the conduit to the new c.u to ensure cpc continuity is maintained??.

It'll be awkward as hell trying to make sure you get a good connection on every coupler, providing you can get the old bushes off without damaging them - maybe using serrated washers?? - if you can get ones to fit that old imperial conduit.

I have to say it's looking more and more like a rewire.:D
 
I've been sent to inspect the wiring at a flat, it's a solid concrete flat with conduit (about 16mm) buried. So trying to pull singles through the old conduit is near impossible. Also none of the sockets have an earth. The flat is on a 2nd floor. What's your views? Idealy a rewire is needed, would a twin rcd be board be acceptable?
Check first,(wandering lead method)for sound earth continuity at every point.You think you have 16mm conduit,its more likely old imperial half inch.IF it does need a rewire,ie is the insulation resistance too low?If you just need to take fly leads to your accessories,you will probably find that the back boxes are pre metric too and you will have to source size 2BA and 4BA screws to fit threaded inserts in boxes. As for changing the board,as you have earthed conduit protection,you only need to consider bathroom circuits and sockets for rcds. It is probably unlikely that you would have sufficient amount of sockets for todays requirements.
If you are going down the rewire route, using existing conduits,perhaps you could install radial circuits if you are having bother with the ring.
 
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sparkymaz

  • Thread Starter Thread Starter
  • #10
errrmmm, dont get me wrong. Saving money is something we all do. Esp. these days. However, in my opinion, a rewire is a definate must. This is obviously an old installation so cables would have degraded a great deal. by the time you have done all the extended testing, sorted any problems. realised someone who has done an alteration at some point and has done something dodgy, sorted that, found the right screws, earthed the boxes, sorted any testing problems out, finding out that the customer wants another socket the other side of the room etc. the list can go on.

after all this, how much longer (and how much more money) would it have taken to just rewire the place?

You've gotta think safety as well, would you really want your name on this installtion and to be held accountable if something should go very wrong?
 
Your remit was to inspect the wiring.This should preferably take the form of a pir.All you are doing is commenting on its present condition.Whether or not you think that "it needs a rewire" should NOT be mentioned on the form.You may of course mention that certain aspects do not comply with bs7671 (2008) etc. You may however submit a separate quote for remedial works which could include a rewire option or other remedial work options.
 
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