help with ring circuit

[davelx]

thanks Sunray, I thought of that but believed that might not be safe as someone may drill into the wall thinking the cable is always runs vertical to the socket either from the bottom or from the top.

The cable path Sunray indicates is within a recognised safe zone and is by far the best way to do it.

 

[Zehroni]

the rightmost socket is too close to the edge of the safe zone for my liking (and it may even be outside it).

what is the safe zone? do you mean it is very close to the corner?, if so, what is the safe distance from the corner. can you please elaborate more.

 

[davelx]

what is the safe zone? do you mean it is very close to the corner?, if so, what is the safe distance from the corner. can you please elaborate more.

If you search the forums you will find loads of posts on safe zones which should answer your questions.

This:
https://www.diynot.com/wiki/b66e76b43318302be55eab5dbeb45ff3

 

[securespark]

Very simply, there is a "safe zone" in line with any accessory, whether it be horizontally or vertically, but not diagonally.

A cable can be run outside these zones as long as the cable is protected by an earthed metal sheath or conduit.

In addition there is a 150mm wide zone on each side of an internal or external corner between walls and walls & ceilings, but not including the floor.

 

[Zehroni]

In addition there is a 150mm wide zone on each side of an internal or external corner between walls and walls & ceilings

I have inspected the new rewiring of the whole house and the extension and there are 3 double sockets that are very close to the corners, about 75mm. I am hoping to get an electrician to inspect the house once I am done to provide domestic electrical installation condition report. will those sockets fail the inspection?, if so what is the remedy please? is a matter of just block them with blank plat and do not use them. there is no way I can move them now.

 

[BS3036]

There is no rule to stop you having a socket close to a corner.

 

[Zehroni]

still need help with this ring circuit, the RCBO tripped again after 2 days and does not switch on. But this time is a soft trip. it is not like the first one with a bang and spark. this tells me that there is no short in the circuit between live and any of other 2 conductors. the tests I did as follows;
replaced the RCBO with normal breaker (the old one) and it works ok without issue

1. measured the resistance L & N for each cable and the values are r1=1ohm, rn=1ohm and r2 =1.3 ohm
2. then I connected L from one cable to N from the second cable and vis versa and the resistance at each socket is 0.8 ohm
3. connected L from one cable to earth from the second cable and vis versa and the resistance at each socket is 0.9 ohm
4. visually inspected the socket and all the connection are in the right place and well connected.

why the RCBO still tripping?

 

[davelx]

You need to measure the insulation resistance between L-E and N-E. You cannot do that with a multimeter, you need specialised test equipment. You are not looking for a short circuit, you are looking for a fault of quite high resistance - it only takes 30mA to trip and RCBO,

 

[EFLImpudence]

Reworded:


Disconnect the cables from the socket and from the CU so you have this"

View attachment 240306

Test between L - N, L - E and N -E (not one end to the other end) on both cables.

There should be very high MegaOhms or infinite reading for all of the tests.

If you have a relatively low Ohms reading on one of them, then that is the faulty cable.

 

[Zehroni]

Test between L - N, L - E and N -E (not one end to the other end) on both cables

this test did not show me the faulty cable. perhaps my multimeter is not sophisticated to measure low ohms. however, I did what I call live test; I connected the wires at the cu to the RCBO, took of all the sockets off and left the 6 wires sticking out from each metal box. then switched on the RCBO, which did not trip. therefore the cable that is going to the first socket from the cu and the cable that is coming back from the last socket are no faulty. then I witched the RCBO off and connected the 6 wires of the first socket with connector blocks, see pic, switched the RCBO on. I repeated this process until I got to the forth socket then the RCBO did no stay on. at this point I realised it is the wire between the third and the fourth socket is faulty. I undid this socket and started testing the ring from the last socket and all worked ok until I reached the same faulty wire. I then replaced it and everything is working . However I am not holding my breath. this is the forth cable I am replacing in the ring. And I hope it will be the last. however, my question is why this worked for few days then went faulty again. this is electricity, and the way I understand it is either it works or not.

 

[EFLImpudence]

Well done.

You obviously have an illusive fault somewhere.

I don't really know what else to advise.
Even with the proper equipment, it can sometimes be a hell of a job to find the fault.

 

[securespark]

Is the circuit wired with a dodgy brand of cable?

 

[Zehroni]

the circuit wired with a dodgy brand of cable?

it is brand new one.

 

[securespark]

Do you know what brand the cable is or where it was bought from?

How long has it been in service?

If you have had several issues already with insulation resistance, you may have more.

 

[AndyPRK]

yeap, I would be replacing some lengths (the ones easy to get to now, but very difficult when its finished. - i.e under floor ones)