running cables to a kitchen island
- Thread starter baxtec1
- Start date
Sponsored Links
You need to ensure:
1) That the cable has an earthed metallic covering, so if it is penetrated by a fixing, that it fails safe.
2) When chasing the floor, that you do not compromise the damp proof course.
Now if it were me, I'd be tempted to cut a small grove in the floor and run PVC sheathed MICC in it before filling over with cement. However MICC is not a DIY job and you'd need an electrician with experience of it (not all do - some domestic only chaps would never have done any)
1) That the cable has an earthed metallic covering, so if it is penetrated by a fixing, that it fails safe.
2) When chasing the floor, that you do not compromise the damp proof course.
Now if it were me, I'd be tempted to cut a small grove in the floor and run PVC sheathed MICC in it before filling over with cement. However MICC is not a DIY job and you'd need an electrician with experience of it (not all do - some domestic only chaps would never have done any)
Why earthed metal covering?
As far as I am concerned this is not required, and the cable could go straight in the floor, though I'd recommend the use of some round PVC conduit or similar.
As far as I am concerned this is not required, and the cable could go straight in the floor, though I'd recommend the use of some round PVC conduit or similar.
AFAIAA, although it's perhaps a little surprising, you are right in saying that there is no equivalent of 522.6.202 - 522.6.204 (cables buried in walls) for cables buried in floors. However, in a more general sense, 522.6.1 requires measures to minimise risks due to mechanical damage, including penetration - and I personally would not think that would be satisfied by, say, T+E buried without adequate mechanical protection within, say, 50mm of the surface of a concrete floor, would you?
Kind Regards, John
Sponsored Links
I would like to see the cables at least 50 mm from the surface of the concrete.
If that depth or greater, I would be happy for the cables to be in PVC conduit - afterall, that's how purpose built flats were built before suspended ceilings became the norm - and those flats had cables criss crossing everywhere in the floor.
If that depth or greater, I would be happy for the cables to be in PVC conduit - afterall, that's how purpose built flats were built before suspended ceilings became the norm - and those flats had cables criss crossing everywhere in the floor.
Trenching a concrete floor deep enough to get a cable 50 mm below the surface has the risk of weakening the floor enough to make it structurally unsafe.
What is underneath the concrete floor ? If there is a room below this floor do not even consider trenching into it.
If the floor concrete is laid directly on the earth then the weakness created by the trench may fail as a result of ground movement that the floor would have resisted if not trenched.
What is underneath the concrete floor ? If there is a room below this floor do not even consider trenching into it.
If the floor concrete is laid directly on the earth then the weakness created by the trench may fail as a result of ground movement that the floor would have resisted if not trenched.
Indeed - in fact, as far as electrical considerations (rather than re-wiring) are concerned, directly buried in the concrete without any conduit would presumably be OK - i.e. directly analogous to the requirement for cables buried in walls.
Whether is is usually/often possible to bury >50mm deep in a concrete floor without compromising structure and/or damp-proofing is a different matter - shallow burying in earthed metal conduit may be safer in those respects.
Kind Regards, John
Yes, again it's the common sense factor.
Don't know how deep the op can cut into the floor, for all we know the island may be having a sink fitted, and a waste pipe!
I guess some discretion can be used about the depth of the cable, and likelihood of it getting penetrated, as it's not a wall, but instinct tells me 50 mm deep is LESS likely to get drilled.
Usually I've seen trenches cut this depth in floors by builders, rightly or wrongly, but impossible to guess what the op's floor is like.
Ultimately I would like to save the op the trouble of using earthed metal conduit or similar - if one is inexperienced in this a right mess could be created.
SWA could be used, but again could be done extremely wrong by the inexperienced.
Don't know how deep the op can cut into the floor, for all we know the island may be having a sink fitted, and a waste pipe!
I guess some discretion can be used about the depth of the cable, and likelihood of it getting penetrated, as it's not a wall, but instinct tells me 50 mm deep is LESS likely to get drilled.
Usually I've seen trenches cut this depth in floors by builders, rightly or wrongly, but impossible to guess what the op's floor is like.
Ultimately I would like to save the op the trouble of using earthed metal conduit or similar - if one is inexperienced in this a right mess could be created.
SWA could be used, but again could be done extremely wrong by the inexperienced.
Sure, my instinct says the same.
Yes, I understand that - and if it were possible to bury unprotected T+E >50mm deep without compromising the floor in any way, then that is probably the simplest approach.
If one were burying more shallow than ~50mm, proper conduit has the advantage that it may well prevent the cable getting damaged (one usually feels a drill hitting it, before any significant penetration occurs) - whilst SWA would give 'electrical' protection, the cable would still probably be damaged by a drill, so the floor would have to be dug up to replace or repair it.
Kind Regards, John
E
Essex1
If the cable is buried at a depth of less than 50mm then it must be in an earthed metallic protection.
Says who, and under what circumstances?
We all have cable buried under our floorboards and there is no requirement for "earthed metallic protection". What scenarios / regulations are you quoting?
Why are you going over this ground which has already been discussed in this thread? Even though what you say is sensible/reasonable, in contrast with the situation with walls, AFAIAA there is no regulation which imposes any explicit requirements in relation to cables buried in floors.
Kind Regards, John
Ironically, if the cable passes through a joist or batten <50mm from the top (which might well violate other Building Regs), there is such a requirement (or alternative), since 522.6.201(ii) invokes 522.6.204 (the same reg we are very familiar with in relation to walls)!
Kind Regards, John
E
Essex1
Says BS7671.
I have not got the regs on me but I am guessing that running a cable in the floor would mean it is being installed outside of the zones agreed in BS7671.
So when this is the case you have two options.
1. Install shallower than 50mm but install earthed metallic protection (conduit, trunking). This is to prevent someone drilling the floor and damaging a cable they do not know is there.
2. Install deeper than 50mm and no earthed metallic protection is required BUT the cable needs to suitable.
E
Essex1
In this case the floor should be treated the same as a wall.
DIYnot Local
Staff member
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local
Sponsored Links
