faults, cables spur from mcb.

[KNIPEX]

i did a perodic test today and have opened a right can of worms.

have to say cant switch main switch of in db so

1st circuit, switch of the mcb disconnect the line from the breaker, disconnect the neutral, and its sparks, ok wrong neutral, however while that cable is still out of the n bar and the same phase is out of the mcb the phase cable becomes live, even though its out of the breaker ???? 170v on it.

put the neutral back in, pull out another neutral and the phase cable becomes live again, only way to stop this is switch off another 3 mcb. a right mess.

2nd prob they have spured off the 32a mcb in the db 2.5 to feed sockets down the other end of the building.
a big no think im right in saying that you can only spur once from a socket outlet not from the mcb.

also in another location they have spured of a double s/o to a single s/o in 2.5, that fine. but then spured of the single to feed another single, bushed together so even though its really a double s/o as such as its so close its still been spured off, again NO not allowed

your views on this would be intresting, thanks.

im back there tommorow to continue my investigation, i dread to think what i might find

 

[eskimo39]

I think you are allowed to run a spur direct from the MCB to one socket only as long as it is on the same breaker as the ring. If it then went to a second socket you are effectivly spuring off a spur which is not allowed.

I also remember reading that you can only spur the same number of sockes as on the actual circuit and these must be from the back of an existing socket or using a JB.

 

[beaver74]

i think you might find that 2 1g sockets will be ok as total load will only be 26A
but appendix 15 does'nt show this set up

 

[hughesy]

i did a perodic test today and have opened a right can of worms.

have to say cant switch main switch of in db so

1st circuit, switch of the mcb disconnect the line from the breaker, disconnect the neutral, and its sparks, ok wrong neutral, however while that cable is still out of the n bar and the same phase is out of the mcb the phase cable becomes live, even though its out of the breaker ???? 170v on it.

put the neutral back in, pull out another neutral and the phase cable becomes live again, only way to stop this is switch off another 3 mcb. a right mess.

2nd prob they have spured off the 32a mcb in the db 2.5 to feed sockets down the other end of the building.
a big no think im right in saying that you can only spur once from a socket outlet not from the mcb.

also in another location they have spured of a double s/o to a single s/o in 2.5, that fine. but then spured of the single to feed another single, bushed together so even though its really a double s/o as such as its so close its still been spured off, again NO not allowed

your views on this would be intresting, thanks.

im back there tommorow to continue my investigation, i dread to think what i might find

Hi mate sounds like a right pain this one just wanted to say you can have a spur from the mcb as long as you only have one single or one double its just one more example of where diversity is allowed

 

[eskimo39]

In the onsite guide, appendix 8.2.4 it states that in a A1 ring and A2 radial circuit a non-fused spur should feed only 1 single or 1 twin/multiple socket outlet. Such spur should be connected to the circuit at the terminals or a socket-outlet or junction box or at the origin of the circuit in the distribution board.

Hope this helps

 

[WarrenG]

I would suggest telling the customer that you are going to have to drop the power untill you can rectify the system. For both yours and their safety.

Unless of course they would like to work on a live board?.........

 

[KNIPEX]

thanks for the replies guys, very helpful

really intrested on your views on the first prob aswell, had anything like this before??etc

 

[randyrat]

Sounds like a bad case of shared neutrals to me......

 

[montybaber]

We were taught at college (a while ago maybe) that spurring from an mcb is perfectly acceptable (only for single outlet though).

why not?

 

[12345aob]

We were taught at college (a while ago maybe) that spurring from an mcb is perfectly acceptable (only for single outlet though).

why not?

whats the feeling on spuring off the ring 32amp mcb with 2.5 t&e -I've seen this alot and when I see this I think to myself I would not do it.

 

[KNIPEX]

here is another one for you, ringmain wired in 4mm2 singles, off 32a mcb, then spured of the socket is 5 double s/o on 4mm2 i know 4mm2 is ok for 32amp however your still spuring of a spur.

have to agree with the above yes neutrals mixed up, however that should cause the line cable to become live when its out of the mcb??

 

[montybaber]

whats the feeling on spuring off the ring 32amp mcb with 2.5 t&e -I've seen this alot and when I see this I think to myself I would not do it.

just out of interest why not?

 

[Tapouchoke]

whats the feeling on spuring off the ring 32amp mcb with 2.5 t&e -I've seen this alot and when I see this I think to myself I would not do it.

od job men and have a go joes who have the therory if the kettle boiles it works

 

[montybaber]

but its fine if the spur is taken from a s/o on the ring?

od job men and have a go joes who have the therory if the kettle boiles it works

i suppose that is me then

 

[randyrat]

Yup....Unfused spur straight from the ring cct MCB in the dist board.....17th says its fine....