Cable Routing/Depth in Kitchen

[jc001]

Hi,

The kitchen in my timber-framed house will be gutted..out comes plasterboard & insulation, and in goes new. Essentially all walls are constructed as per a partition (75mm deep studwork).

Consumer unit is modern MCB type, with RCD protecting lighting (but not sockets – just on the master). Some re-wiring is likely in the kitchen – existing looks ‘bodged’.

I am planning on notching out the studwork by 10/15mm or so and then securing horizontal cables in the notch – plasterboard on top.

Question –

1) is this acceptable based on part P (assuming the cable is protected by an RCD?)

2) The sockets are not RCD protected – sockets are likely to need re-wiring/locating – how easy/feasible is it to retrofit an RCD onto the socket ring? (Consumer unit is MK, 1980-ish, not sure of the make but can check if it helps)

Thanks for any help

(N.B All electrical work will be done by an electrician for part P compliance. I am just planning everything at the moment..)

 

[ricicle]

I suggest you leave everything to your competant 'Part P' registered Electrician considering this :-

RCD protecting lighting (but not sockets – just on the master). Some re-wiring is likely in the kitchen – existing looks ‘bodged’.

Who knows what other horrors will be uncovered.

 

[ericmark]

The protect cables within a stud wall you can either use Ali-tube cable or a RCD. Since one also requires RCD protection on sockets then it would be normal to use a RCD to protect the whole ring main.
However, where it is hard to do this then using either RCD sockets or RCD fuse connection units can allow you to protect just the new installation.
The real criteria used selecting which method is cost.
Using Screwfix prices which can normally be bettered we have around £100 for new consumer unit populated. For an RCD socket around £20 against £3 for standard socket so if you fit 6 sockets then a consumer unit is cheaper.
There is also the 13A RCD fuse connection unit which can feed any number of sockets but kitchen equipment is quite high in current usage and chance of blowing fuse would be quite high. Again using multiple RCD FCU you could spread the load but then cost at £25 per unit means a max of 4 units before it would be cheaper to change the consumer unit.
There are other options a garage or shower consumer unit with one or two MCB’s and a RCD can be used at either main consumer unit position or local in kitchen and at £50 it can be cheaper but room to fit can be a problem.
As to fitting in kitchen I am unsure if replacing a ring socket with a consumer unit will be permitted. Although it would have a 32A supply it would be from feeds of unequal lengths and since registered electricians under Part P have their work checked on random basis if I was the electrician doing the work I would not want to connect a mini consumer unit to a ring main.

 

[333rocky333]

how easy/feasible is it to retrofit an RCD onto the socket ring? (Consumer unit is MK, 1980-ish, not sure of the make but can check if it helps)

If you want one to fit in the board.
Mk changed there sentry range about that time.
New ones are obtainable, only for the later versions

You can tell the range by the part number on the mcb's

 

[ban-all-sheds]

N.B All electrical work will be done by an electrician for part P compliance.

Sorry - do you mean that he is planning on notching out the studwork by 10/15mm or so and then securing horizontal cables in the notch with plasterboard on top?

 

[jc001]

Thanks for your advice all

Im thinking that extending the RCD on the CU to cover all of the kitchen(/house) electrics is the way to go (as opposed to earthed conduit) - Im checking with MK to see that my CU can accomodate this.

Its me that is planning on notching the studwork as opposed to the sparky - why do you ask?

Cheers!

 

[davelx]

Its me that is planning on notching the studwork as opposed to the sparky - why do you ask?

Cheers!

Because sparkys are not permitted to self-certify compliance with building regs of work that they have not done THEMSELVES.

 

[jc001]

Bizzare?

Hypothetical scenario - a new, longer run of cable is needed. It must pass horizontally through a timber upright. To comply with part P, a sparky could not run a new length of cable through an existing hole in the timber upright, but they could (to comply) drill another hole in the upright (say, next to the existing), pass the cable through that and be P-compliant?

Cheers!

 

[rebuke]

No, the sparky could quite happily run it through an existing hole (as long as it complies with all relevant regs), because he can then self certify that the cable he installed complies. If you run the cable yourself, he then can't certify that the cable is installed correctly, as he doesn't know for sure (he can't rely on your word as to how it was installed).

 

[jc001]

Ahh..Now I see..lost in transaltion...

I was planing on notching the studwork so that he can fit/fix the cable! I have a tight timescale on this so every little thing I can do myslef will help me stick to my deadline!

Thanks!

 

[ban-all-sheds]

Have you already found and contracted with an electrician, and discussed your plan and your routes etc, and got his full agreement?

If not, and your plan is that at some time after the event you'll get someone in to do whatever you think is the "final stage" and sign it off, I fear you'll crash and burn....

There's absolutely nothing wrong with you presenting the electrician with notches already done, but you must discuss where they will be with him, as he is the one who has to sign to say that he designed the routes and depth etc.

What about the insulation? How deep is the air-gap between the front face of the battens? Is there another layer of insulation directly under the internal surface boarding, or is it insulated board?

Will you be able to maintain integrity of the vapour control layer given the cut-outs for accessories?

Will the installation method of the cable mean that particular attention needs to be paid to its current-carrying capacity?

 

[Zambezi]

Normal practice would be to drill through the centre of each stud to run the cable.
Plumbers notch joists for pipes though

Also if there is going to be insulation in the stud walls then the cable will have to be de-rated, which means you would need bigger cable. Your electrician would know that.

 

[jc001]

Thanks for the suggestion

I have a sparky lined up (had one in recently to do some other work) but have not discussed my plans with him in detail yet - wanted to get clear in my mind what my options were.

 

[ban-all-sheds]

Get him to pop round asap....

 

[jc001]

Thanks for all your help mate