Bathroom wiring regulations

[jeff]

I am presently getting a bathroom refit.

The bathroom previously had a supply on a spur to an electric shower. The spur is on an RCD at the main consumer unit, but it is not on a ring main.

I want to use the spur to feed the rest of the bathroom. My electrician is telling me that he needs to feed all the way back to the consumer unit to complete the ring.

This will cost $$$ since the path is covered in laminate floor.

Is this necessary or are there other options? Is a ring main a requirement by law? even if the spur is on an RCD anyway? can the ring start and terminate from the spur, so that I can split the spur at an accessible point instead of going all the way back the the consumer unit?

Thanks

[Gary Cavie]

What equipment are you having in the bathroom, to necessitate a ring circuit?

[Roger Mills (aka Set Square)]

Are you sure it's a spur? A spur is usually tapped off part-way round a ring. It's more likely that you have a radial circuit. Is this a single cable which goes right back to the CU with no joins? If so, this is fine for running anything within the current carrying capacity of the cable and its RCD. What size cable is it? What do you want to run off it?

As far as I'm aware, this is not specifically a bathroom wiring issue - the same considerations would apply wherever it was.

[jeff]

I am having a cieling fan, computerized steam cabin, 400w underfloor heating, computerized spa bath (1.5hp motor), shaver socket, lighted mirror, and 2 x downlights. I think that is everything.

[Gary Cavie]

So assuming that the fan, shaver socket, lighted mirror & downlights will run from the lighting cct, that leaves the steam cabin, spa bath and underfloor heating. Do you know what the ratings of those items are, and also what size cable the current 'spur' is fed in, and what the distance run if the cable is?

[jeff]

It is definitely a spur, and it does go back to the consumer unit. My house is really a mess as far as the electrics go. The last owner was a self appointed electrical engineer, and there are a lot of oddities. The wire is 6.0mm (I think. It is thicker than standard 2.5mm cable, but I can't get to it right now to measure exactly)

It might have once been part of a ring, or a spur off a ring, but the consumer unit was moved and it was wired in seperately to the new consumer unit on an RCD.

I am from Canada where the concept of a ring main is unbeknownst to me. Everything is off a spur.

I am not sure of the exact current load for the bathoom, but I want it isolated from the rest of the house as it is running a computerized steam cabin, spa bath (1.5 hp), vent fan, downlights, lights mirror, shaver socket, and 400w underfloor heating.

Obviously, I would prefer not to require a new ring main, as the spur is alreay available, and the ring main will cost me lots of money.

Thanks for any help.

[Gary Cavie]

Again, without knowing the loading of the items, it is impossible to say, but I would have thought that a 6mm cable, in good condition, run correctly etc, would take care of most bathrooms needs. If more power is needed for the items, it would be a better bet to install a completely new cable of 10mm or above, rather than trying to make a ring cct of 6mm cable. 6mm cable under best circumstances should take a load of 9.5kW or so.

Your electrician may be wanting to run separate ccts for the spa and steam cabin.

[jeff]

Thanks for your replies.

I think the fan is on the lighting circuit, as is the main lighting in the room. but the extra 2 downlights and the shaver socket is off the mains, with the steam cabin and spa, etc.

The "spur" is 6mm.

Steam Cabin 3000w Spa Bath 1000w Heating 400w Lights 100w

The total is about 18A @240V.

The cable is about 5m from the consumer unit to the first item in the line, and another 8-10m around the room.

[jeff]

If that is the case then I should be ok, without a ring main.

I would rather not fit one now, as I am getting an extension built which will see the wiring largely re-done.

If I have 9.5kw available, I am only using >5kw, which should not be a problem.

Thanks

[Tournifreak]

I think you may be confusing terms. In very simple terms: A ring circuit is one piece of cable where both ends end up in the consumer unit. A radial circuit is one piece of cable that only has one end connected at the consumer unit. A spur most commonly refers to a single cable joined onto a ring at some point.

As already stated, the lights, fan, shaver socket could all be quite happily wired into the existing lighting circuit - but your electrician should check the loadings. It would be very unconventional to wire then into a ring or radial.

I can't see any reason to have a ring circuit for the items you have described. The 6mm cable you describe should be OK for the other items

-, assuming it is a radial, not a spur. But there could be all sorts of reasons he's not happy to use it. (eg very old cable, unsure of whether it connects to anything else along its run, inconvenient location etc.)

But did you say you're in Canada? This is a uk newsgroup so I suggest rather than paying any attention to any of us, you do what your electrician suggests. He presumably knows the regulations in Canada better than anyone you're likely to find here...

Regards, Jon.

[jeff]

No, I am not in Canada...I am from Canada, but I now live in the UK.

My reason for questioning my electrician is a question of faith. When I asked about the regulations he seemed a bit shakey, and I dont want to pay for something that is unnecessary. Also adding extra work for which a price has not been agreed in advance means the price could be anything. I like to be cautious, as I was stung by a builder before.

You are right in that it is a radial circuit that I have, not a spur. sorry for the confusion.

[Owain]

To carry out electrical work in bathrooms in England and Wales the electrician's employers must be registered with a self-certification organisation under Part P of the Building Regulations[1]. This doesn't necessarily require the electrician himself to have any technical qualifications, but you might want to ask which self-certification organisation (eg NICEIC, NAPIT, BSI, etc) his employer is registered with.

Unfortunately membership of a self-certification organisation isn't a guarantee against less than honest or competent traders.

Owain

[1] If he / his employer isn't registered then (strictly speaking) you're supposed to make a Building Regulations application to the local council. Most people in here treat Part P with something less complimentary than derision.

[Dave Plowman (News)]

If it is a dedicated electric shower circuit direct from the CU it is a radial circuit - not a spur. A spur comes off a ring main.

If you wish to use this radial to feed a variety of things as you've said you'll need to add a second local CU to give correct protection for the wiring to each of these devices - ie treat it like a feed to an outbuilding. Of course the radial must be up to the total load.

[Grumpy owd man]

OP only said it was bigger than 6mm^2...hope it is not 4mm^2!!

[John Rumm]

That is what we would call a radial then... a spur is a term used for a specific case of a single branch from a point in a ring circuit.

More than adequate for you total load by the sounds of it.

See above.

There is no requirement for a ring circuit. The situation for which ring circuits are ideal (and designed) is for providing many sockets covering a wide area - where the loading will be diverse and variable.

Ring circuits are not designed for fixed high current loads (heaters, cookers etc) or loads where there is no real need for the flexibility.

If you ignore the fan and shaver point (typically on the lighting circuit) that leaves you about 4.5kW of fairly fixed and deterministic load - ideally suited to a radial circuit. Depending on lenght of cable and installation method you could just squeeze it onto a single 2.5mm^2 radial with a 20A MCB. If you have as you susspect a bigger cable - even better!

[David Hansen]

On 1 Feb 2006 13:15:50 -0800 someone who may be [e-mail] wrote this:-

It would be worth finding out.

Assuming it is not too heavily loaded, the downlights and shaver socket should be connected to the lighting circuit. I take it that this shaver socket is suitable for bathroom use, ie it has an isolating transformer?

If you get this bit done now then re-wiring will not be necessary when the extension is built.

Presumably this was a radial circuit for an electric shower. There are sometimes advantages in leaving this available for future use. However, if you are sure that this is not necessary then this should be suitable to feed the following loads (but note that nobody here has seen the circuit).

Each of these will need a controlling switch, in a suitable place in relation to the bathroom Zones. I would probably extend the radial circuit to switched fused connection units in a suitable location and then use smaller cable to a suitable outlet. I might use 4mm cable (or even 2.5mm) to make it easier to get the cables into the terminals, reducing the protective device in the consumer unit accordingly.

There are other ways of doing this though and it depends on the circumstances. For instance were the wiring not to be re-done during the extension then I would probably leave the existing radial circuit for possible shower use and install another radial circuit for the steam cabin and so on. This would be a 20A circuit.

[Mark]

Surely the extra cost of the wiring would be negliable compared to the cost of all that? (What is a "computerized steam cabin" anyway? ;-)

M

[Christian McArdle]

Absolutely no problem running this lot off the existing 6mm radial, provided it no longer supplies a shower. A 6mm radial would normally be good for a

32A MCB.

Quite frankly, any electrician that says otherwise (unless there is further information that we don't have) I would regard as incompetent.

Christian.

[John Rumm]

Seems a bit excessive don't you think? Even if you wanted the lights powered from the same radial (not adviseable since its on the RCD), a FCU would sort out the fusing requirements.

[Owain]

If any of the devices are >13A then FCUs can't be used.

Owain