New ring main but have solid concrete ground floors

[Mr M]

I've done a search for this and have read several posts and where a new ring main is to be installed on the ground floor and the floors are solid concrete, the concensus seems to be to chase the wall vertically upwards from the sockets upto the ceiling and drop the cables from the floor above however, the property is also going to have a full damp course done, which means all of the existing skirtings on the ground floor are going to be taken off and replaced.

Would it be acceptable to chase-out the plaster down from the socket positions to the concrete floor and then run the new cables behind the skirtings. The new plaster will finish about 25mm off the concrete floor so perhaps the cables could be tucked within this gap between floor and plaster and be clipped to either the floor or to the bit of exposed brickwork between the floor and the plaster. This would also ensure that the fixings for the skirtings do not catch the cables. Thanks.

 

[Adam_151]

What you propose would not be in a safe zone, and you need to either put the cable at least 50mm deep from the finished surface to avoid penetration from fixings that may be put in now or later (I'm not actually sure I like this method)

Or afford protection via an earthed screen (MICC, FP200, SWA, etc) or mechanical protection such as steel conduit (which should be earthed)

The steel conduit in my opinion is the best way, with a cable with an earthed screen, if you drill into it, you'll short it out and it'll trip out, but you'd still have to fix it (I'd be pretty damn annoyed if it was me that'd drilled into such a cable), metal conduit will hold upto the drill long enough to stop drilling

 

[Job_n_knock]

If someone asked me to chase steel conduit into a wall at skirting level Id walk away and say get someone else or price it too high....sod that for a game of cards. The screen in FP200 isnt an effective earth connection at all. You might consider using skirting trunking. It can be an expensive option but installation is a lot cheaper than chases up above every socket. Work out what you need and ask for a quote from a wholesaler. If you ask the spotty kid behind the counter theres a chance he'll give the max. discount to get the order. Unless he works for CEF where youd need a small mortgage Just a thought

 

[plugwash]

you could use 4mm split con if you can get it.

another option thats allowed by the regs (though many don't like it) is to chase horizontally from socket to socket.

 

[dingbat]

...you need to either put the cable at least 50mm deep from the finished surface to avoid penetration from fixings that may be put in now or later...

I'd also like to point out something that few people consider. The affect on the structural integrity of a wall of a horizontal chase is somewhat more drastic than for a vertical chase.

For a vertical chase the depth should be not more than one-third of the thickness of the wall or the thickness of the leaf of a cavity wall. (not including plaster finish)

For a horizontal chase this limit reduces to one-sixth.

In most cases, cable in safe zones will be accommodated within the depth of the plaster finish, but complying when you run horizontally outside those zones is a different matter.