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Topic Title: Underfloor temp probe - metallic sheath?
Topic Summary: Wet underfloor heating system
Created On: 28 January 2013 11:39 AM
Status: Post and Reply
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 28 January 2013 11:39 AM
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Avatar for sparkiemike.
sparkiemike

Posts: 1513
Joined: 24 January 2008

Working on a project at the moment where there will be a wet underfloor heating system. Some of the rooms will have temperature probes buried into the screed. The probes are connected to room stats which are connected back to the underfloor wiring centre, all at 230V.

Is there a requirement to have the cable to the probe covered with a earthed metallic sheath or conduit similar to the requirements for electric under floor heating?
 28 January 2013 12:21 PM
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alanblaby

Posts: 287
Joined: 09 March 2012

I fitted one last year, it was a 12 inch or so long 'probe' with L,N,and E connections, the outer covering was metal, presumably earthed, so if like this, I'd assume that was compliant.
As for the metallic earthed sheath of underfloor, I asked about this a couple of years ago, and was told the heating element(s) were earthed along their run (warm up brand), so no need for a separate sheath above them.
 28 January 2013 01:30 PM
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Avatar for OMS.
OMS

Posts: 18937
Joined: 23 March 2004

I think mike is talking about the cabling to the embedded probe.

I think we could take a lead from 522.6.100 which requires protection by location, mechanical means, earthed metallic covering or containment or SELV/PELV.

So there is no specific requirement, Mike, but personally, I'd be going for earthed metallic sheath or containment - typically steel conduit (which may also be advantageous when it comes to replacing the floor sensor due to lifecycle or repair)

Regards

OMS

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