Bathroom Downflow Heater

[STEAMSPRAY]

Hello

I have an electric shower wired in 10mm T&E on a 40amp MCB. I no longer need the electric shower and decided to have a down flow heater installed. The electrician came round to give me a quote.

He decided that it was best to use the shower cable already fixed into the walls as it would be difficult to pull out and a lot of tiles would have to be removed. He stated that the MCB would be reduced to 16amp and that 2.5mm cable would be joined onto the 10mm cable via a junction box. The 2.5mm cable would then be connected to a 13amp FCU and then wired to the heater. He said all wiring would be channelled through he walls and there would be no need for heat resistant cable.

I'm not an electrician but I'm not fond of junction boxes as when I previously had the house rewired they got rid of all the junction boxes and used longer lengths of cable.

Can anyone be kind enough to confirm what the electrician has stated is acceptable or would a different approach be suggested.

Many thanks.

 

[flameport]

Provided the junction box remains accessible, then nothing wrong with what is suggested.
The junction box is being used because it would be extremely difficult/impossible to fit the 10mm cable into an FCU.

 

[winston1]

Don't know why he wants a FCU though. Why not make the MCB the correct value, 10A for a typical 2kW heater?

 

[JohnW2]

The junction box is being used because it would be extremely difficult/impossible to fit the 10mm cable into an FCU.

I would have been inclined to say the same - but, in fact, MK FCUs claim to have a terminal capacity of 2 x 6mm² conductors, which would require appreciably more terminal space than a single 10mm² conductor. Having said that, one would be fighting a bit with 10mm² conductors in the FCU's backbox and, given that there is no need for anything more than 2.5mm² (in fact, probably no need for more than 1.5mm²), the electrician's plan seems the most sensible one.

Kind Regards, John

 

[JohnW2]

Don't know why he wants a FCU though. Why not make the MCB the correct value, 10A for a typical 2kW heater?

True, but I suspect that there is probably a desire to have a local means of isolation, so one might just as well use an FCU, rather than a switch.

If an FCU is used (presumably not too far from the new JB), then , strictly speaking, there would be no need to replace the existing 40A MCB with a 16A one.

Kind Regards, John