How to cable to an electric socket in the middle of room with wet underfloor heating

[ey143]

We're soon going to screed our ground floor living room as part of a house rebuild/renovation project with wet UFH under the screed.

If we want a floor mounted socket in the middle of the floor between two sofas in a L shape, to power a lamp / laptop / charger etc, together with a Cat 6 Ethernet socket, am I able to do this given that the floor will heat up around both the socket and the cables that run to these sockets?

 

[winston1]

Never heard if people using floor sockets in a domestic situation, but underfloor heating is not that hot so I don't think it will be a problem.

You biggest problem will be in a years time when "she" wants to change the room around and your sockets end up in a walkway.

 

[bernardgreen]

Maximum safe current for a cable will be reduced by an increase in temperature. But not likely to be a problem.

What I would recommend is supplying the in floor socket via a two pole ( Live and Neutral switched ) FCU or similar means of fully isolating the socket. If ( when ) the socket is damaged or has liquid spilt into it and it is tripping MCB and / or RCD then isolator will allow power to be restored to other sockets.

 

[ericmark]

55˚C for a screeded floor is the maximum temperature, this is the whole problem with underfloor heating, there is a limit to how much heat can be pushed into the room, so it requires very good insulation and heat recovery units or some other form of heating as well. Using thermosetting cable rather than thermoplastic cable there will be no problem. Thermosetting is designed to run to 90˚C instead of 70˚C so it would be like having a ambient temperature of 35˚C with thermoplastic cable. Which is warmer than normal but still well within limits.

So 624B Twin & Earth LSZH Cable 300/500V BS7211 instead of [URL='http://www.batt.co.uk/products/view/685/624Y-Twin-&-Earth-PVC-Cable-BS6004-A05VVH4-U']624Y Twin & Earth PVC Cable BS6004 A05VVH4-U [/URL] it is normally white instead of lead colour slate I think it's called.

 

[chivers67]

Adaptor flex/copex might be able to protect it in the screed too. You can get proper small floor boxes - I know Hamiltons make floor sockets that have a flap for when not being used as opposed to a huge floor box

 

[bernardgreen]

Untitled

• bernardgreen
• 8 Dec 2009
• 1

I think this was an MK socket but it was a long time ago. Tool Station do a stainless steel version

 

[ey143]

With the layout we have in mind and the big TV wall on one side and a wood stove on the other side, it wont be possible to change the layout of the room later - unless you want to watch the fireplace instead of a TV

We have a large open plan kitchen and dining area (total area is like 10m wide and 8m deep with the living room area to one side 5m x 8m and the kitchen on the right side). I'm sure there must be people having two length sofas in an L shape connected with a table, but maybe they are placed against a wall rather than in the open.

 

[Steve]

Given you have yet to screed, can you alter the layout of the ufh pipes slightly so the few rows either side of the socket are spaced away from the socket leaving say 150mm either side? Then heat is no longer an issue at the sockets.

 

[DetlefSchmitz]

For the UFH to work the screed is obviously on top of the insulating layer, which prevents the heat from escaping into the ground. Ours certainly is. So put the cable in conduit underneath the insulation.

 

[ey143]

For the UFH to work the screed is obviously on top of the insulating layer, which prevents the heat from escaping into the ground. Ours certainly is. So put the cable in conduit underneath the insulation.

Yes that is the plan (under the insulation) but it still needs to come up through the insulation and the floor tile and the socket itself will probably get a little warm unless the pipes are kept a little away. Does the weight of all that above, have any baring on the cable itself?

 

[DetlefSchmitz]

The feed to our floor is typically 30°C. You would have a cable in conduit traveling through maybe 50mm of warm screed. I don't think that would be a problem. You could surround the socket with a little insulation too, without compromising the floor strength.

 

[SimonH2]

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• bernardgreen
• 8 Dec 2009
• 1

I think this was an MK socket but it was a long time ago.

Downright dangerous as well - just placed right to slice feet open (I've seen it happen).
Once got sent to help an old school friend of the boss, and being a bit of a yachty type he'd used brass desk fittings in the floor. Unscrew the plug to find a void underneath.

He also had one with hot and cold water and a drain underneath. That was so he could wheel a bath out into the living room, and have a bath looking out across the bay through the floor to ceiling glass.

 

[Spark123]

For the UFH to work the screed is obviously on top of the insulating layer, which prevents the heat from escaping into the ground. Ours certainly is. So put the cable in conduit underneath the insulation.

Yes that is the plan (under the insulation) but it still needs to come up through the insulation and the floor tile and the socket itself will probably get a little warm unless the pipes are kept a little away. Does the weight of all that above, have any baring on the cable itself?

The cable shouldn't be affected by weight if installed correctly i.e. in steel conduit.

 

[bernardgreen]

Downright dangerous as well - just placed right to slice feet open

It is positioned so as NOT to be dangerous.

It is under the second tread which about 14 inches of height above the socket. People starting to walk up the stairs are facing the camera.

That said this type of flapped socket can be a hazard if located where people can walk towards themwhen there is a plug in the socket

 

[SimonH2]

Sorry, I wasn't referring to your particular installation (though I see it looks like that) - but to the fact that when there's a plug in the socket, the flap is just the right height to get feet. At a previous job, they had these at intervals across the very large open plan office. Given that this office was wired BC (before computers), there weren't many of them, and predictably you'd end up with them being used where they were "out in the open". One of the office clerical lasses sliced her foot open with one.