Replacing Existing Immersion Heater Wiring

[topgazza]

So, as a qualified electrician some 40 years ago I feel happy replacing existing wiring but....no longer installing new since 1990
Thought I would check here for some confirmation please. My sons house has an existing immersion heater spurred off the ring main into a fused spur, 13 amp I think, with 2.5 t&e and then flex into the immersion heater. It’s all a bit tatty and he’s having a new cylinder installed.
Sounds simple and using heat resistant flex and fresh 2.5 is is still ok to do a straight replacement as is ?
He doesn’t have any spare ways on his CU anyway. Any advice appreciated

 

[EFLImpudence]

Well, if it has been alright until now, then it will be alright - even if it wouldn't be done like that nowadays - assuming the heater is 3kW.

FCUs and sockets/plugs don't seem to be up to it sometimes.

 

[topgazza]

Thanks. Yes, 3kw
I meant to add I was going to fit a 20A DP instead of the fused outlet as that seems a better protection. Existing flex looks fine in respect of being baked over time. But as before I’ll replace with good heat resistant flex.
Immersion is only used for emergencies if the boiler fails for instance. He has used it twice in 5 years. But immersion tank is clogged up s

 

[EFLImpudence]

I meant to add I was going to fit a 20A DP instead of the fused outlet as that seems a better protection.

Strictly speaking it is no protection: that will then be the 32A MCB. Is it an MCB or fuse?

However, technically it is satisfactory using the omission of overload protection regulations because the immersion cannot cause an overload and the MCB will cover the fault current.

To keep any skeptics quiet you could use 4mm² flex.

 

[topgazza]

I’d use a fused DP switch and appreciate the advice