Consumer Unit question

[PaulP59D]

Hi,

I want to take a cable off to my garden shed from my consumer unit in the garage. The problem is that the consumer unit is an old model and I have had to buy a retrofit kit from MK Electric so that I can fit an MCB type that is currently available.

Fitting the retrofit kit means that I have to go into the CU and extend the busbar. I don't have much experience of working inside CU's. Is it the case that if I turn off the main trip the entire busbar will be dead and safe to work on? I have a DVM, so I am not about to put myself in harms way without checking what is there voltage-wise, it's just that I dont want to commit to turning off the power (with all the ramifications with regard to resetting clocks inside the house) only to find that there is something else that needs to be done for which I am not prepared.

Secondly, since I will be installing a small CU in my new shed/cabin, do even need an MCB for this link in the main CU in the garage? I would guess so in case of shorting/damage to the SWA going out to the shed?

 

[ban-all-sheds]

Fitting the retrofit kit means that I have to go into the CU and extend the busbar. I don't have much experience of working inside CU's. Is it the case that if I turn off the main trip the entire busbar will be dead and safe to work on? I have a DVM, so I am not about to put myself in harms way without checking what is there voltage-wise

Main incomer will isolate.

Do the following to confirm that the DVM is working, and genuinely indicating dead.

1) Measure voltage on busbar

2) Turn switch off, confirm voltage now zero

3) Turn switch on, confirm meter still working OK

4) Turn switch off.

Also, look closely at the switch - there may be a set of holes that you can put a piece of wire through to prevent you accidentally knocking it back on....

Secondly, since I will be installing a small CU in my new shed/cabin, do even need an MCB for this link in the main CU in the garage? I would guess so in case of shorting/damage to the SWA going out to the shed?

You absolutely must have one, for the reason you suggest.

 

[PaulP59D]

Thanks, much appreciated.

 

[JohnD]

Don't know if you've bought the MCB yet, but you might think about an RCBO. This provides the functions of an RCD and an MCB in a single device. Very handy for an outbuilding supply (though an alternative, equally reasonable view is that if the supply fails in the shed, it's more convenient to be able to re-set it in there).

In my opinion more convenient than putting the shed on the RCD side of a split-load, as it means the rest of the house isn't inconvenienced in the event of a shed trip (I love RCBOs but they are a fairly expensive way of doing things, unless you can get them cheap, e.g. used ones on fleabay)