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Wiring Regs Help


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I need a bit of help! I'm a complete novice with wiring so apologies if I'm asking stupid questions...

 

I've got the timber frame drawings ready for me to sign off but before I do I need to make sure that the routing for wiring (and to a lesser extent the plumbing) will be ok - and both my electrician and plumber have just gone on holiday! The issue I have is that there are quite a few steel and timber beams in the construction due to a large open plan area and I don't know whether the few holes the designer has put in the beams will actually be sufficient.

 

So, what I'd like to understand is what the regs do and don't allow with routing the wiring. Ideally I'd like to go up to the joists from the plant room (where the consumer unit will be) and just route where needed but there are some areas that are more of a challenge. If I can't fully route through the joists could I take some of the wiring through the service cavities, either just above the floor/skirting or just below the joists? What are the rules about routing from ground to first floor?

 

The designer has offered up the possibility of a couple of 85mm holes in each beam (although accepts that this isn't really an area that he understands) but is this really sufficient? I realise this is a tough one to answer without seeing the plans (which I'm happy to share) but as a general rule, is there a mass of wiring everywhere or is it a case of 2 or 3 wires in a loop?

 

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The rules are simple and based on "safe zones"

 

You can only run a cable in a wall in a "safe zone" and a safe zone is either horizontally or vertically from any accessory, or within 150mm of the ceiling.

 

 

You cannot run cables at skirting board height, you cannot run them at an angle, only horizontal or verical.

 

Now, given most rooms have sockets on all walls and the normal socket height is 400mm above the floor, then you can run a whole bundle of cables around the rooms at socket height. So except in rooms that don't have sockets, that may be your route? there is aloways the within 150mm of the ceiling safe zone but personally I don't like that but it is legal.

 

I am wiring a house just now with some steel beams and there are just two 90mm holes in each steel, and it would appear the plumber has first choice at using the available holes, on the basis it doesn't matter so much if my cables have to take a longer route. But it is a PITA.
 

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I think one will do, it just means some cables have to be longer than they otherwise would.

 

In all probability, if you take the entire bundle of cables that connects to a consumer unit, they would all go through one 90mm hole.

 


 

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1 minute ago, ProDave said:

In all probability, if you take the entire bundle of cables that connects to a consumer unit, they would all go through one 90mm hole.

 

Cool. That's a lot better than I was expecting!

 

We're going to have extra cabling for internet, TV etc but not a massive amount, so hopefully a few 50-85mm holes will have us sorted :) 

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Have you thought about any low voltage or signal cables - alarms, ethernet, aerials, thermostats? They should not run parallel to 230v mains else signal will suffer. You might get away with passing them through the same hole in the steel but ensuring they are split apart before and after (i.e. minimise the length you have them bundled together).

 

Edit - sorry just re-read your post you have this in hand.

Edited by ragg987
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28 minutes ago, ragg987 said:

Have you thought about any low voltage or signal cables - alarms, ethernet, aerials, thermostats? They should not run parallel to 230v mains else signal will suffer. You might get away with passing them through the same hole in the steel but ensuring they are split apart before and after (i.e. minimise the length you have them bundled together).

 

Edit - sorry just re-read your post you have this in hand.

No probs. Re-reminders are always appreciated :) 

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4 hours ago, ProDave said:

 

I am wiring a house just now with some steel beams and there are just two 90mm holes in each steel, and it would appear the plumber has first choice at using the available holes, on the basis it doesn't matter so much if my cables have to take a longer route.
 

 

Priority trade mate B|

:D

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