Running hot water supply and electrical cable together.

Hi all

I am doing up the kitchen and have internally insulated the three of the walls with 50mm thermoboard. I thought it would be a good idea to leave a gap at the bottom to run pipes and cables around the bottom of the walls and up to the kitchen units. I need to run gas, hot and cold pipes and the ring main cable. The guy doing my heating and electrics is uncomfortable with this and wants to drop the electricity cables down vertically from the ceiling thereby cutting a swath through my thermoboard. Is he being over cautious? Isn't there some way to run them together using conduit or lagging or even a decent spacing between the cables and pipes, I can make the width of the channel as wide as necessary.

Any suggestions appreciated.

Reply to
Rednadnerb
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I am not sure but I think there maybe legislation which dictates which route the cable goes.

Reply to
SS

If youre running them next to hot pipes, measure the max temp of the space, allow another 10C rise for summer conditions, and derate cables for use in that temp ambient.

NT

Reply to
NT

I just googled 'derating cables' and can now see why he wanted to avoid the situation. It turns out that running gas pipe buried in thermoboard is frowned upon so we're going to drop the pipes through the ceiling and box them in and leave the cables running around at floor level.

Thanks anyway.

Reply to
Rednadnerb

Rednadnerb wibbled on Thursday 01 April 2010 13:43

Gas pipe =25mm from electrical cables according to my OnSite Guide (the reference there is to BS6891:2005 clause 8.16.2). The distance may be reduced "if a pane of insulating material is interposed" or the gas pipe "is PVC wrapped".

Cold water and electrics - main issues are access to soldering joints by plumber (ie is he going to stick a blowtorch on the cable) or mechanical damage due to wielding spanners/wrenches.

Hot pipes - normally a reasonable gap and/or pipe insulation would be OK in free air (say under a suspended floor), but burying a pipe and a cable in an insulated trench which is what I understand you have, is not something I would contemplate. Reason - you'd really have to assume the ambient air temperature in that void *may* reach the temperature of the hot pipe at worst. If that is 70C, your PVC cables are now derated to zero (ie they are at their maximum temperature). Even at an assumed 50C air temp, you'd be upsizing your cables. I am assuming that the pipes will be covered? If not, sections may become implicitly covered by the units???

You really want a separate route for the electrics. You are going to have to apply derating for enclosing them in insulation anyway. A little more detail on your proposed "trench" could be helpful.

So, no, I think he is right to question this.

Given there is often a void at the back of the units, how about a surface run in conduit for good measure, somewhere upwards, where the cable is behind the units? This is what I have done.

HTH

Tim

Reply to
Tim Watts

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