closing the ring

[onzadog]

If the ring should close at the same place in the consumer unit, does it have to go all the way back to the consumer unti to terminate or can it joint back anywhere so long as all the sockets are inside the loop?

I'm asking as we had a new boiler fitted and the power is supplied of the old radial line for the water heater that's now gone. However, the new combi boiler only requires 5 Amps.

My plan is to convert this radial into a ring so I can have a spare socket in the loft and the main reason is someone at some point has run the bathroom extractor off the upstairs lighting circuit. I\\\'d feel happier is the fan/boiler and spare socket all ran off one 30 Amp ring.

Does this make sense?

 

[Dr_Doolittle]

The ring must start and finish in the consumer unit. Otherwise you effectively have a 5mmSq cable connected to a 2.5mmSq cable going back to an mcb.

 

[onzadog]

makes perfect sense when you put it like that. I guess my plan was a little ambitious. Maybe I should just run the three items off a radial line.

Thanks.

 

[davy_owen_88]

If the ring should close at the same place in the consumer unit, does it have to go all the way back to the consumer unti to terminate or can it joint back anywhere so long as all the sockets are inside the loop?

Think what you are proposing for a moment... The whole idea of the ring circuit is that current can flow through both legs thus spreading the load between them. If you connected one leg to the other somewhere further round the circuit, then all the current will have to travel through a single length of cable at the start of the circuit. Since 2.5mm² t&e is only rated at 27A, and the ring circuit at 32A that would be wrong.

I\\\'m asking as we had a new boiler fitted and the power is supplied of the old radial line for the water heater that\\\'s now gone. However, the new combi boiler only requires 5 Amps.

Has it been suitably fused down or fitted with the correct cable?

My plan is to convert this radial into a ring so I can have a spare socket in the loft and the main reason is someone at some point has run the bathroom extractor off the upstairs lighting circuit. I\\\'d feel happier is the fan/boiler and spare socket all ran off one 30 Amp ring.

Bathroom fans generally are powered by the lighting circuit because you want it to come on when the room is occupied ie when someone turns the light on.

Was that the reason you wanted the socket in the loft? If so you don't need to bother as what you have is fine. If there was some other reason then you don't need to go through the hassle of making it a ring just for one extra socket and extending the radial or running a spur would be more than sufficient.

 

[onzadog]

As the cable goes up through the old cupboard, it has a 13 Amp fuse, this then leads to the boiler and has another fuse, 5 Amp this time. I was thinking of adding a socket between these two fuses just in case I need power up there. The business with the extractor fan is that it currently doesn't work and there is black making of the exterior wall. So it looks like it suffered catastrophic failure at some point in time. It used to be operated by a pull cord that no longer moves. The supply for this comes from the back bedroom lighting but there is no fuse or isolator for the fan either in the bathroom or the loft. If I'm going to replace it, I obviously want it as safe as possible and without whatever happened last time happening again. The scorch /soot marks worried me at first but all the electrical stuff is on the inside end of the hole and as I said, the marks are outside the hose so I'm a little confused as to what killed it. Maybe it was just an old tired dirty motor and it's last effort was to extract it's own soot!!!!