Two CU's??

[Milky17]

Hi I need a bit of advice please. I've been removing a burglar alarm which is fed from a fused spur on 1.5 T&E. When isolating the circuit I found that it wasn't fed from the main CU, there is a seperate box next to the CU with a single switch protected by a 5a cartridge fuse and the only thing this powers is the alarm.

Would it be ok to just leave this switched off and cut the T&E back as I'm getting the wall plastered in the next couple of weeks

 

[Adam_151]

No, someone might come along at a later date and accidentally switch it on.

You should disconnect the live and the neutral inside the switchfuse, snip off the stripped copper and tape over the ends, ideally label it as to what it was

Be carful when opening the switchfuse, the incomming terminals will still be live when the switch is turned off, and often the plastic shrouds which are supposed to cover them a little bit are missing

 

[Milky17]

Do you mean disconnect in the switch next to the CU of in the fused spur? The fused spur is on the wall I'm getting plastered so i want this gone completeley?

If it was accidently switched on and the cable had been plastered over what would happen?

 

[Adam_151]

Do you mean disconnect in the switch next to the CU of in the fused spur? The fused spur is on the wall I'm getting plastered so i want this gone completeley?

disconnect in the Switchfuse thats adj. to your CU (you may have called it a 'single way cu'...)

If it was accidently switched on and the cable had been plastered over what would happen?

Depending on how the end was, one of the following:

i) If shorted, you might be lucky and it go bang
ii) You have a live cable in the wall with no visible accessory waiting for someone to drill into it
iii) Water gets into end, you get a volatage gradient across the wall and gives those touching it a shock

 

[Milky17]

Ok thanks for your help, I'll disconnect the cable in the switch.

Why would this be here in the first place? It's obviously older than the main CU, so wouldn't this have been incorporated into the CU when it was installed?

 

[Adam_151]

Ok thanks for your help, I'll disconnect the cable in the switch.

Why would this be here in the first place? It's obviously older than the main CU, so wouldn't this have been incorporated into the CU when it was installed?

Are you sure its older? these things normally get added in when the CU is full and theres a need for an additional circuit, if its a DIYer job it may be one thats been ripped out from elsewhere!

Or if the CU was changed, it may have not been incorporated for various reasons, possibly installer couldn't be bothered to, couldn't trace where it went, etc. Probably amounts to corner cuting, but don't have enough info to fully understand why it was done

 

[bernardgreen]

, there is a seperate box next to the CU with a single switch protected by a 5a cartridge fuse and the only thing this powers is the alarm.

Where does this box get its power from. Is it from one of the fuses / circuit breakers in the CU or direct from the cable between the meter and the CU ?

If it is direct from the meter then its removal is NOT a DIY job.

A photo would help.

 

[Adam_151]

Bernard, I read it as that he wants to get rid of the final circuit and fused spur, not get rid of the supplying switchfuse

 

[bernardgreen]

Hi Adam

I was being super careful about what the OP was going to and the advice offered. Removing the wrong cables in the switch box next to the consumer unit would be very dangerous.

I have seen at least one wired "upside down" with the feed going the fuse and the output taken from the switch.

 

[Milky17]

The switch doesn't get it's supply from the cu as the alarm circuit was still live with the main switch open.

I have test equipment and insulated tools so I would be very cautious while doing the work.

and no i'm not removing the switch, i just want to disconnect the alarm circuit so there's no chance the cable can become live