Cable query

Bodgeitandleggit · Posted: Sun Apr 01, 2012 8:54 am

Hi....putting new flooring down in the extension downstairs and noticed that the socket is fed from another socket on the other side of the room but the cable feeding it is going under the raised concrete floor which used to be a garage ....not sure if it is in conduit or just buried.....last home owner said the house had been rewired a couple of years before I bought it and new fuse box with breakers in and survey did confirm this but my query is ...is this normal to do this and is it safe and can be left, also the socket it is feeding is hardly used so I can disconnect

bowlingo · Posted: Sun Apr 01, 2012 9:51 am

I would disconnect it from the socket, mcb/fuse, fused spur, junction box etc thats feeding it. If the cable is linking the ring together (should be 2 cables in each socket) then I would rewire the leg of the ring. I have seen concrete react with the outer sheaf of a twin and earth cable and cause it to break down

Bodgeitandleggit · Posted: Sun Apr 01, 2012 10:11 am

bowlingo wrote:

I would disconnect it from the socket, mcb/fuse, fused spur, junction box etc thats feeding it. If the cable is linking the ring together (should be 2 cables in each socket) then I would rewire the leg of the ring. I have seen concrete react with the outer sheaf of a twin and earth cable and cause it to break down

Will do.........thanks

mfarrow · Posted: Sun Apr 01, 2012 10:30 am

The risk assessment in my head is telling me:

- The house has been rewired 2 years ago so it's pretty safe to assume that adequate precautions were taken when installing the cable, unless it's obvious that they were not.

- The circuit board feeding the socket I'm assuming has a modern RCD/MCB setup which will detect and disconnect any faults.

- If a fault occurs, it's under concrete so the risk of fire/electrocution is very slim to none.

Bodgeitandleggit · Posted: Sun Apr 01, 2012 10:55 am

mfarrow wrote:

The risk assessment in my head is telling me:

- The house has been rewired 2 years ago so it's pretty safe to assume that adequate precautions were taken when installing the cable, unless it's obvious that they were not.

- The circuit board feeding the socket I'm assuming has a modern RCD/MCB setup which will detect and disconnect any faults.

- If a fault occurs, it's under concrete so the risk of fire/electrocution is very slim to none.

1...I think it was rewired about 5 years ago and when looking in the socket it is all new cable and sockets but not sure why it was put under the floor and not run up/down the wall
2..yes its a modern RCD/MCB set up...done when rewire was..

3..dont want a fault occuring ...

I may just discon as I hardly use it anyhow

PrenticeBoyofDerry · Posted: Sun Apr 01, 2012 12:37 pm

If the CU was installed during rewire, can we assume the cable colour cores are all as new brown (phase) and blue (neutral) ?
Is this also true of the colour cores at the cable in question? If so the IR reading should have come up very high (>200 Megaohms) on your electrical installation certificate, does it?
Best way to prove safety, is have the circuit tested out.
If the IR reading stated on the EIC, have not reduced significantly, I would not be over concerned.

Bodgeitandleggit · Posted: Mon Apr 02, 2012 10:37 am

PrenticeBoyofDerry wrote:

If the CU was installed during rewire, can we assume the cable colour cores are all as new brown (phase) and blue (neutral) ?
Is this also true of the colour cores at the cable in question? If so the IR reading should have come up very high (>200 Megaohms) on your electrical installation certificate, does it?
Best way to prove safety, is have the circuit tested out.
If the IR reading stated on the EIC, have not reduced significantly, I would not be over concerned.

Cheers derryboy...it is the new colour code..tbh I have disconnected it anyway but if I require it again I will get it tested before reconnecting..

ericmark · Posted: Mon Apr 02, 2012 1:04 pm

Are you sure socket no longer works? It could be part of the ring and disconnecting in that case could produce an overload.

bernardgreen · Posted: Mon Apr 02, 2012 1:18 pm

mfarrow wrote:

so it's pretty safe to assume that adequate precautions were taken when installing the cable,

You are the eternal optimist

.

mfarrow wrote:

has a modern RCD/MCB setup which will detect and disconnect any faults.

Not all faults will be detected, a loose connection can over heat without causing over current or earth leakage so MCB and RCD will not be aware.

mfarrow wrote:

- If a fault occurs, it's under concrete so the risk of fire/electrocution is very slim to none.

Damp concrete is not an insulator. A damaged live conductor embedded in damp concrete without the CPC in contact with the concrete ( to provide route for earth leakage ) can present a shock hazard of live concrete that will not be seen by the RCD. It might be seen when something or someone provides a path from live concrete to an earthed item.