A couple of electrical questions.

I'll be re-wiring the house over the next few months and replacing all of the electrical accessories.
Firstly, what type of switch should I use for the immersion heater and the central heating timer. A 13A FCU (Screwfix p/n D15777) or 20A DP Switch (Screwfix p/n D13639)?
Secondly, the existing consumer unit is one of the old bakelite ones which has probably been here since the house was built in the 50s. I've bought myself a new split load consumer unit with MCBs. I want to disconnect the existing wiring from the old CU and connect it to the new CU. This should make it easier for me to changeover from the old wiring to the new wiring as I have more ways on the new CU than I need.
My idea was to disconnect the existing wiring from the old CU, connect them to some terminal strips (e.g. Screwfix p/n 17672) mounted in a sealed box and then extend the wiring from the terminal strips to the new CU using twin & earth. Is this viable? If not, could someone recommend another method.
Cheers
Andy Kelly
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The immersion heater will need a 13A FCU. Are you using one or two switches? It is normal for two switches to be used (ie a FCU downstairs where the immersion is turned on/off and then a double pole switch where the 2.5 T&E changes to heat resistant flex in the airing cupboard). If you are using just one switch (eg it is in the airing cupboard) then use a 13 amp FCU
I assume your CH timer is conneced to a gas boiler or similar. If so you need a FCU and a 3 amp fuse. This must isolate all the power to the CH system not just the timer.

as
them
twin
This would work as it is only on a temporary basis
HTH
Adam
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of
the
switches?
Just the one switch. A radial from the CU. The CU is under the stairs and the airing cupboard is at the top of the stairs.

I'll have to do some investigating here. One thing I've learned since moving into this house is: Assume Nothing!
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I would not use an FCU -- I would use a 16A MCB protected circuit with no further fuses. The extra 13A fuse adds nothing safety wise, but is a potential failure point for poor contacts and overheating. Use a 20A DP switch adjacent to the immersion heater. Any additional switches can be single pole, but you'll probably find double pole ones easier to find.

If you can temporarily run the whole house off the highest current fuseway in the old fusebox, then use this to temporarily supply the new CU, and connect all the circuits into the new CU properly. If you have any high current appliances like an electric shower or electric hob, this isn't viable unless you leave it disconnected until the new CU is correctly connected in. You will need to temporarily interconnect tto the new CU with suitably sized cable; because of the requirement to derate conductors protected by rewirable fuses, this will need to be suitable for higher current than the fuse protecting it.
The earthing in a 1950's installation will be well below current requirements. Suggest you start by bringing that up to current requirements directly into the new CU, and don't simply take an earth connection from the old fuse box.
--
Andrew Gabriel

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"Andrew Gabriel" wrote in message

of
the
switches?
T&E
I agree this a most acceptable method (in fact my local council now use this on their rewires). I have somewhere in the depths of my confused/mad/pissed brain that BS 1363-4 is a FCU reg and thought it was a requirement. I believe either method is OK.
Adam
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