Damn fool electrical questions

[GB]

We have a combined heat and light unit in the bathroom that has failed. One of these.

It's a pretty ancient and lethal design, but apparently it's approved for Zone 3 in the bathroom. This particular light is actually in zone 2, but it could be moved pretty easily to zone 3.

Can anyone suggest a combined heat and light fitting that is less lethal than this one and suitable for zone 2, please? Or even zone 3?

The right way to do this is to run a spur off the ring main, but that would involve channelling the walls, as there's no 13 amp supply above the ceiling. So, I think it's sensible to opt for something that runs off the lighting circuit.

Finally, there is an immersion heater in the bathroom. I suppose I could take a spur off the supply to that, but I'll have to check the fuse rating and the immersion heater power consumption.

[Brian Gaff]

I have a 750 w heater in the bathroom running off a light circuit its been in for years. Not being able to see what you have, what makes you say its lethal? Brian

[ARW]

Does it have to be combined heat and light?.

[GB]

No. That was just what's there.

[GB]

It's got a radiant ring heater. The whole unit is made of metal. The user who was present at the time says it went bang but didn't blow any of the fuses. It may not even be earthed!

[ARW]

Maybe something along the lines of

might be better with a separate light.

If set to 1kW you may be able to power it from the immersion supply if the immersion supply is a standard supply ie In old money an immersion is 3kW at 240V so ran at 12.5A Adding an extra 1kW would push this up to

16.6A, Normally this would be fed from a 16A MCB or 15A fuse and would not cause a problem.

If the immersion is only used for emergencies then it is not a problem.

[ARW]

It's a round quartz heater and light.

Used to be used in bathrooms some years ago before central heating was used.

[tabbypurr]

looks like a tubular metal element. no problem.

no problem

element failure is the most likely culprit

it may be anything, but most likely it's a heater that has been installed sanely.

NT

[GB]

Thanks. I'll get one of those. I suddenly remembered the built in wardrobe, so I can run a cable up inside that and across the ceiling, so that will power a decent fan heater.

The immersion is the only source of hot water. :)

1970-built house, with a central electric storage heater. Gas only came to the area much later. Fortunately, I like Artex.

My new neighbour has just installed a gas boiler in his bedroom. And he's replastered the ceilings, so I assume he doesn't like Artex.

[GB]

But I don't think it's legal to replace it like for like, as it's a zone

3 heater going into zone 2.

It was earthed, btw.

[FMurtz]

We use things like this sometimes in Australia.

[ARW]

No chance of taking power from the sockets?

BTW if you wanted to swap the fitting like for like your chances of death in that bathroom is no greater than it was in 1970. You are hardly likely to try touching the light whist you are in the bath are you.

[Tim Watts]

There's no Zone 3 anymore.

If this light is >2.25m above the floor, it is outside the zones (even if over the bath) so you can do what you like:

[T i m]

So if my bathroom ceiling is 2.4m high ...

"Yes, 230 V fittings may be installed above a shower or bath but they must be at least IPX4, i.e. enclosed and water protected."

Was that heater / light IPX4?

And it would (now?) have to be on an RCD (and would a light cct typically / traditionally be on a RCD)?.

Cheers, T i m

[Harry Bloomfield]

[e-mail] expressed precisely :

Looks like a silica element to me, a sort of glass. There is certainly a problem if all that metal is not properly earthed.

[Tim Watts]

Green book: 701.512.2:

"Installed electrical equipment shall have at least the following degrees of protection:

(i) In Zone 0: IPX7

(ii) In zone 1 and 2: IPX4

...

Nothing is said (as far as I can see) for anything outside of the zones.

But that doesn't preclude using common sense. I would not install the unit described over a bath.

[T i m]

Ok.

No, me neither, or not on any ceiling height where it could be touched anyway. ;-)

Cheers, T i m

[ARW]

The OP did say it was earthed.

Now he also said that the house was built in 1970 (lighting circuits were required to be earthed from 1966).

However as you have pointed out it needs to be properly earthed. The presence of an earth wire (cpc) does not mean that it is earthed.

It would now be a good time whilst replacing the fitting to test the earth. It does not need to be a earth loop tester, a simple multimeter is all that is needed.

I would, if at work, take an earth loop reading and record it on my job sheet.

[John Rumm]

What makes you say that?

That brings an additional circuit into the room, and requires another circuit to be included into the bathroom's equipotential zone - not a big deal, but it does require a bit more work than might otherwise be expected.

If its a 3kW heater on a 16A circuit, then you will probably get away with a 1kW heater in addition.

[tabbypurr]

it could be either

but no basis for claiming it's not earthed.

NT