dodgy wiring?

[wayneward25]

Hi,

Ive changed a double socket today and tested the 2 lives coming into the back and 1 was dead, I presumed it was a ring circuit as it has a 32a mcb.

I took off a couple of sockets to see if any wires had come loose from the back of them but everything was ok but again once I removed the 2 lives one was dead.

I checked the consumer unit as I was concerned this could be a radial circuit bearing in mind there are 24 double sockets on this circuit!

The cable is 2.5mm csa and has a 30ma rccb connected.

When I removed the cover there were 3 live conductors going into the mcb, although not to 17th edition I initially thought it could be a ring circuit and a radial going into the 1 mcb.

I removed all 3 cables and attached each one to the mcb to find out which was connected to the socket I was working on, I tested the other 2 that were not connected and they were both live also.

Initial inspection seems to suggest that each room has aprox 4 to 5 sockets and are spurred although I cannot locate where from,

But I cant figure out why all 3 cables at the mcb are live, any suggestions whats going on here??

no fused connection units anywhere

 

[ricicle]

Is this your own house ?

 

[wayneward25]

no a friends who has recently moved in but apparently it was rewired 2 years ago although there is no paperwork from who ever did it.

We wanted to get a periodic inspection done on it to get some uptodate paperwork but if its like this whats the chances of getting it passed, and if it needs floor boards etc taking up to inspect it further is it going to be cheaper to just have it rewired?

 

[EFLImpudence]

You should not be working with live wires.
Continuity testing should be used.

What were you using to test?

What voltage was at the conductors?

 

[wayneward25]

i used a unitest telaris voltage was 243 volts

 

[wayneward25]

so any ideas?

 

[EFLImpudence]

Ive changed a double socket today and tested the 2 lives coming into the back and 1 was dead, I presumed it was a ring circuit as it has a 32a mcb.

Not the correct way to test but same result, I suppose.
End to end continuity test should be used.

I took off a couple of sockets to see if any wires had come loose from the back of them but everything was ok but again once I removed the 2 lives one was dead.

Still leaves 21.

I checked the consumer unit as I was concerned this could be a radial circuit bearing in mind there are 24 double sockets on this circuit!
The cable is 2.5mm csa and has a 30ma rccb connected.

Ok.

When I removed the cover there were 3 live conductors going into the mcb, although not to 17th edition I initially thought it could be a ring circuit and a radial going into the 1 mcb.

That's reasonable.

I removed all 3 cables and attached each one to the mcb to find out which was connected to the socket I was working on, I tested the other 2 that were not connected and they were both live also.

Strange.

Initial inspection seems to suggest that each room has aprox 4 to 5 sockets and are spurred although I cannot locate where from,

How do you know if you have only removed three?

But I cant figure out why all 3 cables at the mcb are live, any suggestions whats going on here??

Well, the first thing to do is discover from where the power is coming.
Find which mcb turns off the power to these conductors.

Once you have done that you will have to disconnect sockets and trace the route of the cables by continuity tests, not live tests

 

[wayneward25]

the 32 a mcb turns off the conductors

 

[wayneward25]

i ended up removing nearlly all of them to trace the cable back but just goes under the floor

 

[wayneward25]

I would have thought it be could practise to have a radial and a ring circuit into seperate mcbs

 

[EFLImpudence]

It is allowed to have a spur wired from the mcb (in with the ring) but it shouldn't be more than 3m. and to only one socket or FCU.

Obviously it wouldn't be live when disconnected.

 

[wayneward25]

so could it be possible that they have run a circuit under the floor and just spurred off it and maybe parralel cables hence the 3 lives?

 

[wayneward25]

either way it sounds like a bodge job to me more importantly how would this effect a periodic inspection

 

[EFLImpudence]

Anything is possible.

Have I understood correctly that all three wires are live when disconnected from the mcb?

 

[wayneward25]

no when all 3 are disconnected they are dead but add any 1 and all three become live