Legal Part P Question.

[jlspam1]

I'll get the obvious out of the way so as to avoid silly posts and questions.

Yes I am rewiring my house. Yes I am aware of Part P. Yes I have a building notice in force allowing me to do this. Yes I have a friendly competent to help test and advise when needed. Yes I have spent months preparing and researching. Yes my house is currently a non-complaint mess that I am trying to fix. No, I threw out all my non harmonized cable and have no intention of using any. Yes I will sleeve up any remaining non-harmonized and test it thoroughly before using (I have some cable buried behind stuff I do not want to move at this time). Yes I have the correct test equipment. And, finally, yes all the work will be tested before the LABC will sign it off. (and yes, I realize the design/installation sections of the paperwork will not be signed)

There, now onto the questions (sorry about the preamble, but I am getting tired of this).

The existing CU is a Tenby, I've decided that even though 17th is a while off I'll be 17th compliant (why not, it makes sense). So I see three obvious options :-

1. RCBO the current CU - this is probably the easiest option, no doubt the most expensive.

1. Buy a 16th split and swap one RCD for a switch and then RCBO that half. Currently 16th splits are cheap as chips (no doubt wholesalers are getting cold feet about unsold stock and impending 17th). Also this is an expensive option as well.

2. Swap the CU for a 17th part CU.

1 is a problem because its a temby. I know its compatible with Legrand and I suspect Contactum - but the RCBO are a teary 48+VAT each. Thats probably going to be a show stopper for me - so does anybody know a cheapio source of RCBOs for this make. (no not fleabay, I don't want to have to play around testing them until the circuit is finalised). If I could get them for the more normal 26+VAT then I would probably go for this option as it is much less hassle.

2 should be compliant by my understanding, but then I'd still want a switch (cheap) and 3 or 4 RCBOS (not so cheap). But all the makes are flogging the 16th CU cheap and the main brands (MK would probably be my choice) have RCBOS for the 26+VAT.

3 my local wholesaler has a 17th contactum CU which seems like a good deal

I know they deliver next day as I have used them before. This seems like an attractive offer.

Any advice people?

Also its worth pointing out that I have not changed a CU before (fitted one out yes, so 1 is also an easy option) so any advice people can offer would be gratefully received. I do have a lot paperwork and a few instructional DVDs so I am not that concerned. Also, most importantly, when I had the meter and inlet moved a few years ago I had an 100A isolator fitted between the CU and tails so for me the job is much, much safer then for most people.

Still - I'm not proud and I gracefully accept advice from people with experience. My main question is making sure all fittings and attachments are good and tight and proper - I would guess there are some tricks of the trade to be learned there. I don't want to bother my friendly competent too much (I am relying on him to test all the works once finished, and that will be one time consuming job).

The last question is about isolation in kitchens. I have been reading up in my copy of 16th and it clearly states that isolation is only needed for fixed kitchen units and a switched socket counts as an isolator for non-fixed units. My friendly competent says that he would mark down any installation that did not have an isolator for all units regardless of if they were on sockets or not. I'm talking freezers and fridges that are not fixed but slide under the work surface. What is the viewpoint on that? how should 16th part be read on this issue? If he is correct then my only real option is the spur the two under work surface sockets up over the work surface and then back down and fit a FCB at he top as the isolation. A right royal pain that would be to remove some tiles and refit - but if I must. Also it would be more or less impossible to meet the recommended 2m distance, I could manage maybe 1m but my kitchen is tiny, I would more or less have to have the unit under the worksurface and the isolation direct over it 1ft over the worksurface. That is a recommendation naturally, not an obligation

- but one I could not meet. By my reading as they are removable items (floor standing) and on switched sockets they are isolated anyhow and do not need additional isolation. Comments?

Many thanks in advance to people to read this and have sensible helpful comments.

[Mungo "Two Sheds" Toadfoot]

Got bored here.

You're asking people to help you... FREE. If you can't put up with a few stupid answers go and get an electrician.

Si

[newshound]

er, yes. Isn't that the point of uk.d-i-y? Post seemed reasonable to me....

[Andy Wade]

Is that a list price or your wholesaler's best offer? It sounds to me like the former, with room for at least 45-55% discount. As you need several tell your wholesaler how much you're expecting to pay and see if they'll bite.

MK have long offered a "main switch and dual RCD kit" (hitherto for TT installations) making it easy to build a so-called '17th edition CU' with two 30 mA RCDs. Divide your lighting circuits between the two sides, for obvious reasons.

The best source of guidance here is the EGBR - the Electrician's Guide to the Building Regulations, published by the IEE/IET. It's fairly clear:

- sockets supplying equipment pushed under a work surface should be accessible when the appliance is pulled out, examples cited are dishwasher, tumble dryer, fridge;

- built-in (integrated) appliances should be supplied via sockets or FCUs that are readily accessible when the appliance is in place and in normal use, or supplied via sockets/FCUs that are controlled by a readily accessible DP switch or switched FCU;

- "readily accessible" above means that control switches must not be hidden inside storage cupboards;

- all wiring accessories to be mounted on the building fabric, not on kitchen furniture.

See first point above. No separate switching is required if the sockets are accessible when the appliances are pulled out.

What 2 m distance is this? Cooker control switches for ovens and hobs should be no further than 2 m from the appliance(s) they control (but should not be directly over the appliance) - that's the only 2 m rule I know of.

[John Rumm]

probably...

Not much better than 1

or make up an equivalent using MK like Andy described or by having more than one CU fed from split tails after your isolater.

Not tried Temby, so can' comment directly. Contactum / Hager / MK are all generally interchangeable though.

I have used lots of contactum CUs in the past, and generally find them quite nice to work on. Plenty of space.

Since you have a switch, changing the CU is hardly any harder than fitting one out.

If fitting one from scratch make sure to check the default wiring in them first - I had one out of the box that would have shorted the supply if it had been connected up as supplied!

Using a big enough screwdriver seems to be the main thing.

My personal preference is to have above counter isolation switches for anything that obscures it's socket. This is not actually required by the regs, but in practice seems to make sense. I have seen a tumble drier burst into flames before; and I want not want to have to pull it out of a recess under a worktop to be able to reach its plug to isolate it!

A common workaround is to place the supply socket at the back of an adjacent cupboard such that the plug can be withdrawn without moving the appliance. Its arguable whether this still counts as "readily accessible"

The only reference I have seen to 2m I have seen is as a maximum between a cooker and its isolator.

[Rumble]

If RCBOs turn out to be ubiquitous for 17th Edition compliance, then the price of them will fall dramatically as demand goes up 100-fold. Currently, RCBO's are rarely used for domestic installations (compared with MCB's), hence the ridiculous price.

Might be worth playing a waiting game and seeing what happens with the price of RCBO's over the course of the year.

[John Rumm]

It seems more likely that CUs with multiple splits will become the "normal" solution.