Part Pee?

[Tim S]

Dave Osborne coughed up some electrons that declared:

Is it though?

What in engineering terms is different between a sub board of one over current device, and a fused spur? One is clearly allowed to change an fuse spur device.

What about a breaker in a shed on the end of a distribution circuit from the main house CU?

How does having a mini board in the shed (sockets and lights) fed from, say a 32A circuit differ conceptually from taking a 32A circuit directly to the shed sockets, with a 5A fused spur for the lighting (a common enough arrangement)?

What about using a 3 module "CU" in the same example above, fed by a 32A circuit, with the shed sockets coming off the load side of the isolator, and a 6A MCB for the lights (we assume the 32A feed is RCD protected)?

I don't think it's actually that clear cut. The MPs would probbaly like it to be, but it isn't IMO.

Cheers

Tim

[Frank Erskine]

I suppose a 'straight replacement' is literally like-for-like, i.e. a maintenance replacement rather than an upgrade.

Then again, is 'like-for-like' an identical replacement, or. for example, changing say a fused Wylex to a fused MK?

Or changing a Wylex 4-way to a Wylex 8-way?

Is, in fact, a 'consumer unit' legally defined, or is it just a posh switch-fuse?

[John Rumm]

I think "part P" is the approved doc - I don't think the SI has a letter as such does it?

ok, perhaps "all" was too strong. The "vast majority" may have been better.

Made worse by the SI now being the tool of choice since it can delivery a cartload of legislation without the troublesome business of having to bother parliament with it. (IIRC for 2007 there were something like 2700 new bits of legislation that were enacted - less than 30 were actually debated in the house, the bulk were rubber stamped through under a SI.

It would be easier if we were French. We could then just ignore it and not lose any sleep over it!

[neverwas]

Grovel, grovel.

While looking for other building regs stuff I have just come across S.I.

2006/652. That amended S.I. 2004/3210 so the let-out from Part P in Schedule 2B (Descriptions of work where no building notice or deposit of full plans required) applied to:

"Work consisting of -

(a) replacing any fixed electrical equipment which does not include the provision of-

(i) any new fixed cabling; or

(ii) a consumer unit;"

So the Approved Document is in line with the regs. And I guess I'd better go hunker doen in my foxhole .

On the other hand, it does seem to put the position of consumer units in t'other strand of this thread beyond doubt.

[neverwas]

The 2004 SO.I. inserted a real "Part P" in Schedule 1 to the 2000 regs. You can see it on

It looks bloody harmless too: around half a page of stuff you cannot argue against.

Spot on. And MPs don't even scrutinise primary legislation properly any more.

True. But then again, I don't deserve any sleep in this cold and damp foxhole after getting the law wrong :(

[John Rumm]

I don't think there really was doubt - only wishful thinking.

Still, another thought experiment to demonstrate the law is an ass:

According to the notification rules; you can extend an existing circuit, but not install a new one. Presumably this is because adding a new one means opening the CU and making connections in it.

So you could add a spur to a ring circuit. However BS7671 allows a spur to be placed anywhere on the circuit - including at its origin. So you can't open a CU to terminate a pair of cables at a MCB for a new ring, but you can open it to terminate a pair of cables for a couple of new spurs on a ring.

[Simon (Dark Angel)]

I take it then, as long as the installation was correctly installed in the first place and it's a like for like swap than that's OK then?

The reason I ask was in the program they were saying if you are not Part P registered and were doing ANY alectrical work in the bathroom you had to notify the council.

[The Medway Handyman]

Where would we be without any rules eh?

[Mike]

Surely you don't replace the whole thing in one go, you do a breaker at a time :)

[Andrew Gabriel]

There's a lot of misunderstanding about Part P, most particularly in the electrical contracting industry and the Press.

[Dave Osborne]

Well, I guess what I'm saying is that your argument seems a bit too hypothetical.

I think the spirit of the legislation is that changing the consumer unit is a big job and shouldn't be tackled by amatuers.

I have to say I agree with this, because I've assisted friends on a number of occasions who would happily tackle any electrics in their home, but bottled out when it came to changing the consumer unit without someone there to hold their hand.

Further, you are unlikely to change a consumer unit like-for-like. The new one's probably going to be split load, with more ways, etc.

You also are obliged to sort out your main equipotential bonding (i.e. bring it up to the standards of the current regs) when you change the consumer unit, so again it is often not a case of replacing like for like.

If you have a mess of Henley blocks and various switch fuses, then are you really going to want to leave that arrangement as it is? When you want to strip it all out and put a nice new integrated solution in, then that's not changing like-for-like, so it's notifiable.

OTOH, I wouldn't worry about a 3-way consumer unit in a shed. If it's broken, swap it out.

[Tim S]

Dave Osborne coughed up some electrons that declared:

I agree with all of that, especially as the action of changing the protective devices effectively alters all the circuit charactersitics[1] and ideally one would (should) test the circuits to ensure Zs compliance with the breakers, and to locate any long overlooked faults (especially on ring final circuits as these aren't always apparent) - and as you rightly say, bonding (main and supplimentary).

[1] Through replacing an open wire fuse with an RCBO or RCD/MCB combo box is generally going to improve things, assuming you don't whack a load of type D's or higher current C's in!

I was just being hypothetical...

Cheers

Tim

[<me9]

Replacing old plug in wylex open wire fuses with wylex plug in MCBs is not replacing fixed equipment.

Or is it?

[<me9]

And it says somewhere you're allowed to replace the case.

[John Rumm]

Agreed, but that was the point really, highlighting the inconsistencies in the wording.

Presumably because they don't like the idea of unpaid people doing work they can't tax?

You agree with what; that changing CU is a big job, or that legislation ought to proscribe non professionals from doing it?

Applied to other electrical accessories that would still be like for like. e.g. replacing a single pendent lamp holder with a multi bulb chandelier. So swapping one domestic CU for another could be "like for like"

(note I am not arguing that part p permits changing CUs without notification)

Upgrading main EQ bonding is specifically stated as not notifiable though.

Other than the time required to do the job, there is not much difference between them really. You need comparable levels of skill, and knowledge to do either.

[ARWadsworth]

Can you change a dbroken MCB via the DIY route?

Adam

[Dave Osborne]

John, Thanks for your comments. I've no more to add.

[John Rumm]

Can't find much in there on changing protective devices... it would not be a CU replacement, so perhaps you could argue you could.