Replaced a garage consumer unit in my SILs shed last weekend.
Easy enough because we could kill the breaker in the house.
But I wondered, how is it done if you change the CU in a house?
There isn't an outside 'stopcock' for electricity.
Is it done 'live'?
Dave - The Medway Handyman www.medwayhandyman.co.uk
1) Pull the cutout fuse;
2) Disconnect CU tails from henley block if you have one;
3) Work live;
4) Operate main isolator if fitted;
5) Operate meter's built in isolator if the right type.
1 - EDF charged me 35 squid to pull and refit the fuse - they took all
day to come back. This would be the most painful way, but arguable the
"correct" way in the absence of other options. My seals were newish.
If the seals are broken or are not new looking, they might "fall off"
allowing you to pull the fuse. HOWEVER be warned that old and flaky
cutouts fed by paper insulated cable dating to 1940 show never be
touched as a) The cutout may break up in your hands or b) the cutout
comes off the wall, bends the now brittle and dried out cable and it
dumps a short circuits worth of metal plasma in your face.
2) Technical working live, but with the right tools, good access and
done carefully is not particularly dangerous. I have done this. I do not
recommend anyone else does.
3) The most dangerous option - so much as to be a non option for anyone
who is sensible. It is probably done sometimes. But there is no need.
4) Some supply companies do fit these. I fitted my own. EDF were not
hugely keen but they put up with it anyway.
5) Do check - certain makes/models of meter do have an isolator built in
- some Siemens types.
Well they contain a contactor that can disconnect the supply. Even if
they offered a facility for you to call them and arrange a temporary
disconnection, would you trust it not to reconnect when you least
I replaced a secondary extra CU once where the main cutout was decidedly
dodgy looking. So opted to disconnect the tails to the CU in question at
the henley. Its very minimal live working since once the tails are free,
they are not live and you can stick the lid back on the henley.
The only challenge with that one was the henley had allen headed screws,
and I don't have any VDE allen keys. So I used a hex bit in a mag holder
cocooned in insulating tape, and stuck it in my cordless drill.
On Sun, 03 Aug 2014 09:44:33 +0100, Tim Streater wrote:
Most installations have that as part of the CU that is being
No one has mentioned the pole fuse outside. Ours was only about 8'
off the ground until they came round replaced it, the stays and
capping over the earth bonding etc. It's now about 16' above the
ground. It only feeds us so pulling that wouldn't cut anybody else
That is where I have head the term used. However the water supplies would be
in a wet riser (IMHO) and things get more complicated in high rise flats
where there are dry riser pipes intended for use by fire fighters.
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