quick confirmation on a 'leccy regs point

[JJ]

I think I've got this right, but confirmation would be nice.

I'm rewiring sections of my house (yes, under building notice and I have a friendly part P certified professional ready to check it all out for sign off) and I've designed my circuit and am busy implementing it.

Its a lighting circuit, and a section of it is in a utility area and looks are not important here - cost, access and correctness come first. I've chosen to use 20mm round conduit for cable protection and would like confirmation on use of connector blocks. BS7671 clearly states that they must be enclosed, so I'm using 15A connector blocks fastened securely in the round T's accessory (these things

on the junctions of the conduit - I think this should satisfy both the requirements for access and mechanical protection and allow me to wire up the three utility rooms clearly. Fyi, its obviously a 6A RCBO on the circuit and a standard lighting configuration.

Any comments?

I might use the remaining 20mm conduit for the mains spur in that area as well, but that would be a single spur on a 13A FCB from the ring and all junctions would be inside the sockets/FCB as I do not think

30A connector blocks would fit as handily in the round conduit accessory boxes.

And while I'm asking questions, has anybody used fire proof expanding foam as a sealing measure to block a missing brisk to meet fire regs? The old 60s wiring job passed a load a cables through a missing half brick which I will need to seal (just one of a multitude of sins from that old wiring job..).

[RobertL]

I thought they could only certify their own work.

Robert

[John Rumm]

Sounds fine. The screwed connections remain accessible but within an insulated enclosure.

What you describe is ok, however I would ask: Is 13A enough for a utility area? If you are only installing one socket (single or double) then there is no need for it to be a fused spur. If you are installing more than one, would you realistically expect people to connect more than one high current appliance?

Not used it, but I am sure it will do the trick. That is after all what it is for!

[dennis]

They can certify that they have tested someone else's and that its ok. Just like the guy that had the electrician go bust will have to do. The test is about £100-£120 around here in the midlands if the local BCO orders one.

[JJ]

Hi Robert,

As I understand it the inspection form is in 3 parts. 1 & 2 are circuit design and installation - and these can only be signed off for work that is done by the electrician.

part 3 however, is the test section and this can be done for any work and its this section that is filled in for wiring inspections only.

building control will sign off the notice on part 3.

at least I'm pretty sure thats the case, if anybody wants to correct me then please do!

[JJ]

a fair point - I've been giving this one some thought since you pointed it out.

whilst the only main appliance is a washing machine the spur is no problem, if I add a tumble dryer then it is a problem.

but a spur is much easier to route there then extending the ring - but as I have no yet finished the ring I have a few days to think about it.

I'm not sure that 2x2.5 TE would go in a single 20mm round conduit if I was to extend the ring - I seem to remember the regs being quite strict on the number and types of wires that can go through a conduit of any given cross section, but I can check that easily enough when I get home. Failing that this excellent link

everything I would need to check if I could not wait. It would be better to put 2x 20mm conduits side by side but that would be an absolute arse and only if I had to.

I might just stick to the the single spur for the time being.. but I now see that as the lazy option.

[JJ]

Bugger that, just done some quick research. It would go, just, but then I'd need to derate the circuit down to 20A from 32A. I will probably extend the ring and use 2 parallel runs of conduit. (not to mention even with inspection points feeding it through would be an total mare of a job)

Or run a spur on a 13A FCB as planned. I'll decide in a few days, thanks everybody for your input!

:)

[John Rumm]

While this is true - its not an official route to part P compliance. Many LAs have gone down this route however. It ought to be a part P registered bod can do the work and then self certify, or it can be done under a building notice. If the latter then LA may then choose how they verify the work is ok - this may include commissioning a PIR or some other testing. This ought to be at their expense.

There is no official way for a third party to self certify someone else's work - unless they are prepared to claim it was their work.

If the BCO wants extra payment then play hardball with them, and suggest they read section 1.26 in the part P approved document. ;-)

(This is no guarantee they will play by the rules, since the approved docs are not binding)

[JJ]

Cheers for that Mr. Rumm - it more or less echos my experience with BCO locally.

They tried everything they could do disuade me from getting a building notice.

They refused to be bound by the Part P section which explicity states that they should pay for the tests.

They came back to me a few days later and said that on discussion an inspection was all that was needed to close off the notice as long as its by a Part P competent. And paid for by me. And documented for their files.

All this inspite of the fact that Part P is meant to leave provisions for keen DIYers - they certainly do not make it easy.

Don't misunderstand me on this - I actually think Part P is a good move in concept, as there are some right ffing cowboy DIYers. But I've spent months reading up, have a mountain of documentation/books, have a complete set of test tools (ok some are slightly out of cal) and I'm doing my level best to do absolutely everything according to regs in the fashion that I want - I really really wish there was some clear clarification on how BCOs were meant to implement it.

[John Rumm]

Adding sockets to a ring such that they form part of the ring is actually quite easy - even if you need to take both new cables to one existing socket location. (disconnect one existing cable and crimp it to one of your new ends, and join the other new end to the other old cable with the socket)

link

> gives everything I would need to check if I could not wait. It would

Does it need to be in conduit. If appearances are not important then it could be surfaced wired. No de-rating needed there. Failing that, chasing in is not that difficult.

The choice is yours. Although if you do add a drier, you may be cursing taking the easy route ;-)

[Norman Billingham]

Bugger that, just done some quick research. It would go, just, but then I'd need to derate the circuit down to 20A from 32A. I will probably extend the ring and use 2 parallel runs of conduit. (not to mention even with inspection points feeding it through would be an total mare of a job)

Or run a spur on a 13A FCB as planned. I'll decide in a few days, thanks everybody for your input!

It will go but is very difficul to install - virtually impossible to install the conduit then pull cables through it unless its very simple straight runs.

As a general point is there any reason why you can't just use single strand cables in conduit? Most industrial installations seem to do it that way.

[Owain]

things

on the junctions of

Bad practice IMHO, using wiring in conduit all the connections should be made at the points, not in the middle of conduit using connectors. The unexpected location of the connection may make later fault finding difficult.

If you're doing it under a building regs application then you don't need an electrician to sign anything, Building Control should take care of all that for you.

Owain

[js.b1]

Is this a white painted brick utility room?

If the wall is bare...

- Fit 20mm Round Conduit to the wall

- Conduit shall be continuous AND erected before cables drawn in

- Draw in dual 2.5mm or single 4mm 6491X from the ring

Continuous means just that - 6491X is unsheathed.

Alternatively instead of using conduit you could use a surface run cable such as FP200 or BS8436 in white clipped to the wall. Their sheath is slightly tougher (medium impact rating) than conventional PVC flat-twin-&-earth and acceptable run on the surface in domestic (AG2).

If the wall is plastered...

- Create a chase in the plaster

- Fit in dual Oval Conduit or Capping

- Run dual FTE 2.5mm from the ring

What is the point of Conduit or Capping under plaster?

- #1 - to protect from the plasterers trowel

- #2 - to permit cable replacement without removing plaster

Obviously for #2 to be possible the conduit/capping would need to be a straight run be it vertically or horizontally between a) floor/ceiling & wiring accessory or b) wiring accessory & wiring accessory. Old capping was sized too tight to the cable making it difficult to remove cable if the wall is bellied outwards (bricks pinch cable against capping), modern capping is a little more generous but the problem can still remain - avoided by either channelling or use of oval conduit.

Generally domestic does not use 20/25mm round conduit much - BR "A" limit a chase to 16mm for a cavity wall leaf.

If the utility room will get a washer & dryer...

1 - Ring should remain balanced That is the load in each "leg" of the ring should be balanced rather than at one end. An imbalanced ring would be where one "leg" of the ring is 6m from the CPD whereas the other "leg" is 25m from the CPD - the load would be unevenly balanced between the two legs. 2 - Washer & Dryer should not be in the same double socket A double socket is 19.5A continuous rating, whilst a washer & dryer DO cycle their elements modern washers are "cold fill" so heat water for longer and a dryer can be running for quite some time in a busy familly. So it can be better to plug them into separate 13A sockets. 3 - Ideally I would run twin 20A radials for each of dryer & washer Some may prefer a dedicated 32A ring because otherwise if one 20A radial trips someone will no doubt try to plug both appliances into the remaining 20A radial which can be a short-lived solution :-)

If this is a "bare brick" utility room with surface wiring I would run twin 20A radials back to the CU in FP200-variant or BS8436. You could run two 13A radials spurred off the ring via SFCU, depends on whether that makes cable routing any easier.