notching and drilling for cable

[essgee]

Hi All,
I am putting a loft conversion in my house and moving a few walls about internally, large sections of the house are being stripped back to the studwork.

The current Distribution board needs replaced, and given that some of the circuits include a mixture of sockets across 2 floors, and sockets and lighting in the loft I thought it might make sense to do a more thorough job of the re wiring.

In order to save a bit of money I will run the new wiring, and then as I'm not Part P certified a local electrical firm will come and make the connections, do the tricky/tecnical bits, test and fit the new distribution board. I have already spoken to them so I'm clear on what I can and can't do.

So to the question, well ok, so the FIRST question; when running cables Building regs state that cables have to be drilled through the centre of joists when running new wiring. I presume it is ok to use existing notches where they exist as 1- I am replacing existing runs, and 2- there is no point making swiss cheese of my joists when there is an existing notch I can use.

Doubtless there will be more questions to follow!

Many Thanks

 

[PrenticeBoyofDerry]

If you are routing your cable through notches, they need to be mechanically protected. To prevent nails and screws being put through them.

http://www.tlc-direct.co.uk/Main_In...Index/Necessities~Cable_Protection/index.html

 

[ban-all-sheds]

In order to save a bit of money I will run the new wiring, and then as I'm not Part P certified a local electrical firm will come and make the connections, do the tricky/tecnical bits, test and fit the new distribution board. I have already spoken to them so I'm clear on what I can and can't do.

Have you cleared this approach with the council? Are they happy with it?

Doubtless there will be more questions to follow!

You need to be careful asking them here - you'll be expecting the firm you engage to issue a certificate, so it's what they think that matters, not what anybody here says you can/should/cannot do.

 

[essgee]

Hi,
I've had an unofficial chat with a building control officer who recommended the firm I'm using because they are who the council use for testing. As far as Building Control are concerned so long as they have a completion and testing certificate they are happy.

You make a valid point about opinions on her versus what the local firm would want, and I completely agree, it is just that I thought this one was a quick and easy question and didn't want to bother the electrical firm with it, as really they are doing me a favour that saves me an awful lot of money.

The running of circuits isn't complicated, it is getting access to do, ( runnign under floorboards, chasing cables etc), that is time consuming and therefore costly. Also I get to be anally retentive about having switches perfectly level, and lights in alignment! I did a full circuit diagram which the firm have approved, and so they will just fit the new distribution board and do 'the difficult technical bit', and test as they would any other house they had just walked into.

Sooo, does anyone want to offer a quick answer to this one, or do I need to call the electricians?!

 

[ban-all-sheds]

You had an answer....

If you are routing your cable through notches, they need to be mechanically protected. To prevent nails and screws being put through them.

http://www.tlc-direct.co.uk/Main_In...cessities~Cable_Protection/index.html[/QUOTE]

Even if existing holes and notches are in the wrong places, not using them won't make them better.

 

[essgee]

Oh I do apologise, I managed to miss that reply as I scrolled down.
Thank you both.
Susie

 

[PrenticeBoyofDerry]

When a cable is installed under floors or above ceilings it must be run so it is not liable to damage by contact with floor or ceiling or fixings.
So cables routed through joist should be at least 50mm from the top or/and bottom of the joist.
If not they should be provided with some form of mechanical protection, that will prevent damage, this can be safe caps, steel conduit or the use of armoured cable.

 

[essgee]

It is interesting actually as I presumed the drilling through the centre of the joists was to protect the structural integrity of the joist- which is why I didn't want to turn the joists into swiss cheese just because building regs said to drill holes. I haven't come across these protection plates before but they would save me having to drill new holes.
Thank you.

 

[PrenticeBoyofDerry]

You should be able to get them from most electrical wholesalers, if you have a screwfix nearby, they sell them in packs of 20 for £3.36 per pack.
If holing joist or notching them they too should be done to a regulation size.

Heres a guide
http://www.eastdevon.gov.uk/bc-guidancenote7-notchingofjoists.pdf

but remember the 50mm(ceiling and/or floor) or mechanical protection for cables.