We're building new house and need some advice on the electrics...how long do the tails have to be from meter to consumer unit? also, where does consumer unit have to be in relation to water supply?
Ideally the CU should be fitted in a suitable place, taking the envirioment located in to consideration.
Being close to the incoming water supply is no big deal, in fact it will be quite handy have the meter and the mains earth terminal close so you can bond the earth conductors to the water pipe.
Meter tails no longer than 3 metres and voltage drop will need to be calculated.
I think the only requirement is they have to be protected from hot pipes.
the length is open to interpretation as it isn't specified. I have heard from 2M to 5M and everyone swears their interpretation is correct. You can do longer, but there must then be a double pole isolator close to the meter. This is common, for example, in blocks of flats. Be aware though that running long meter tails can be a nightmare when it comes to the regs on mechanical protection/RCDs/discrimination/burying cables etc etc.
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