Bathroom circuit for heated mirror from redundant immersion circuit

4 Feb 2007
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United Kingdom
I’m in the process on renovating our bathroom and taking out the copper cylinder etc, well not me a plumber. At the back of the airing cupboard is an old 16amp immersion circuit that is no longer used. The immersion heater was removed when I installed the CH about 35 years ago. The outlet is roughly in the position above a new vanity unit being installed. Can I put a 3amp fused outlet on the end of the cable after removing the immersion heater switch. The idea being to power a heated mirror/shaver outlet. The immersion circuit has nothing else on it and has been turned off at the CU.
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you probably need RCD protection if you don't have it already ?

an RCBO in CU ? or fused /RCD FCU if its not in the bathroom
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There seems to be a lot of discussion on other forums about putting an FCU in a zone 2 area of a bathroom. Some say it is classed as switch gear, i.e. removing the fuse cartridge is in effect a switch by then isolating the connected unit. The idea was to place the FCU higher up the wall and run a cable inside the wall to the illuminated mirror. Thoughts please.
Unless your FCU is IPX4, or IPX5. no.

Zone 2:

"The minimum degree of protection for equipment installed in zones 1 and 2 is IPX4, or IPX5 where water jets are likely to be used for cleaning purposes. An exception to this requirement is a shaver supply unit complying with BS EN 61558-2-5 which, although it does not meet the requirements of IP4X, is permitted in zone 2 but must be located where direct spray from showers is unlikely. This type of shaver supply unit is the only type that is permitted in a bathroom or shower room."

My vanity unit 600mm wide will be next to the end of the bath, so I guess within zone 2 with the FCU located just below the ceiling. I have to build a small partition wall leading into the bathroom, and wondering if it’s better located there I would pull back the cable from the current location drop it to the FCU high up on the partition which will be outside the bathroom then run a new cable from the FCU to the mirror light. Obviously this is only if the FCU is not acceptable in a position above the vanity unit.
Well you could just change the Mcb in the cu to 6A or 3A if you are comfortable working in the cu.

Maybe the tidy way.

Do we need an fcu or protective device reducing ?
Yes could do that, just thinking that the circuit could be used for other services possibly, not sure what, so thinking the CU stays at 16A and I step down outside the bathroom.
Unless your FCU is IPX4, or IPX5. no.
Does the fact that unswitched FCUs are not marked as IPX4 mean that they are not? Can only things marked as such be so?

What IP rating would you give an unswitched unfused flex outlet plate even if not marked? That is a blank plate with only the screw holes obviously filled with screws.
Does the fact that unswitched FCUs are not marked as IPX4 mean that they are not?

I would not expect an ordinary FCU to have any particular resistance to water.

Protects from splashing water, no matter the direction. IPX5 – Protects from water jets at any direction. IPX6 – Protects from powerful water jets. IPX7 – Protects in water up to 3 feet (1 meter)

Are you thinking of IP4X?
The enclosure must provide protection against solid bodies greater than 1mm in diameter. The test uses a 1mm dia. 100mm test probe wire which when applied with a force of 1N+/?10% must not be able to enter the enclosure.
Or forget using the redundant immersion circuit and power the vanity unit from the lighting circuit. That's the normal way, and no FCU needed

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