quick question regarding removing redundant circuit CU
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quick question regarding removing redundant circuit CU

by dan_m2k » Fri Apr 24, 2009 9:12 am

I'm after a bit of a 'sanity check' on my part...

Through trial and error I've discovered that some wall lights that I intend to remove are connected to the upstairs lighting MCB in the CU. I've taken the front of the CU and it appears that there are 2 lives coming from the top of that MCB. I've traced one to lead downstairs and the second to lead upstairs-- see pic (it's no.2 from the left)


So, to disconnect the redundant wall lights all I need to do is:
1) Main switch off the CU, Cover off the CU.
2) Loosen the screw top of the MCB
3) Remove the live to the wall lights from MCB 2.
4) Remove the neutral from the same cable from the row of neutrals on the right.
5) Cover back on the CU, Main Switch on.
6) Test to see the dead circuit is indeed dead with a multimeter and test the upstairs lights work.
7) Remove the redundant cabling.

Thanks for any help.

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by kbrownie » Fri Apr 24, 2009 10:15 am

I can't view your picture.
Your nearly right,
Before you take step 2, you need to prove the circuit is dead that you are working on, just opening the isolation switch does not prove that.
So test for voltage before you continue to step 2 onwards,
I must also add that each circuit should be protected by it's own Breaker/fuse so having two lighting circuits(down and up stairs) on the same breaker is not recommended.
When you test your circuit you should make sure that your test equipment is functioning correctly prior to and after test by using either a proving unit a or known supply.
Do use an approved multi meter or a voltage indicator to test circuit not a neon screwdriver they are a bit like the banks, they can't trusted.

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by moggy1968 » Fri Apr 24, 2009 2:35 pm

in essence, thats ok, BUT
check that the consumer unit is really dead when you flick the mainswitch. If you don't have a remote main switch (i.e. the only one you have is on the consumer unit) be aware that the CU input is still live and will give you a fairly nasty (and possibly terminal!) shock if you inadvertantly touch it.
I would suggest using a pair of proper electricians insulated pliers to handle everything, and insulated screwdrivers, they aren't terribly expensive, keep your fingers out!
don't forget to remove the earth from the cu
remove the detached cable from the CU immediately after disconection and before switching on. you don't want loose cable flapping around in there!
Be extremely careful, going into consumer units, if your not used to it is dangerous, if your at all unsure, get an electrician in.

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