Proximity of 2.5mm T&E to GCH pipes?

Been off-plot for sparkying for some years, but did many rewires, kitchens, etc, before Part P arrived. Just had new GCH installed, ladder principle across the ground / first floor void with 2.4m drops to ground floor radiators.

There's an ugly two-pipe drop into the living room I'm about to box in with 9mm MDF, then paper over the box. Easy. I want to add a pair of two-gang mains sockets, and share the pipe-run box with the 2.5mm T&E. The GCH pipes are 50mm apart, so I'll make the box 100mm.

I've read the rules and interpretations online, no firm guidance there. The T&E is rated at 70 degs C max, and GCH is nominally 60 degs C max when it leaves the boiler 20 feet away. Obviously, that temp will drop after 30 mins and the house is up to heat, but being boxed in, that temp might well hit 60 degs C inside the box. I can stuff the gap between pipes and cables with insulation, or I could vent the box discreetly at ceiling and floor level. The wall is a single pile of extremely hard 2'x2' block, which I'm unlikely to be able to chase out because it supports half the front of the house and I don't have a diamond cutter or the tools to chase.

To the assembly, is this do-able: your views, please?
 
Been off-plot for sparkying for some years, but did many rewires, kitchens, etc, before Part P arrived. Just had new GCH installed, ladder principle across the ground / first floor void with 2.4m drops to ground floor radiators.

There's an ugly two-pipe drop into the living room I'm about to box in with 9mm MDF, then paper over the box. Easy. I want to add a pair of two-gang mains sockets, and share the pipe-run box with the 2.5mm T&E. The GCH pipes are 50mm apart, so I'll make the box 100mm.

I've read the rules and interpretations online, no firm guidance there. The T&E is rated at 70 degs C max, and GCH is nominally 60 degs C max when it leaves the boiler 20 feet away. Obviously, that temp will drop after 30 mins and the house is up to heat, but being boxed in, that temp might well hit 60 degs C inside the box. I can stuff the gap between pipes and cables with insulation, or I could vent the box discreetly at ceiling and floor level. The wall is a single pile of extremely hard 2'x2' block, which I'm unlikely to be able to chase out because it supports half the front of the house and I don't have a diamond cutter or the tools to chase.

To the assembly, is this do-able: your views, please?
Any cables boxed in and surrounded by insulation, will under normal loading, be inclined to heat up quicker than cables in normal containment, and break down earlier,than cables in standard containment. IE:- conduit, trunking etc. depending on the diversity of the circuit, ( Assume 100%) give thought to up grading the size from 2.5 mm to 4mm. I have know domestic circuits being installed with MICC "cable" ( PYRO) only by sparks doing their own properties, thats an extreme solution. The up side is that it will last considerably longer than T&E ( Appx 30 years.)
 

OneTenner

LE
Book Reviewer
You could use CY LSOH which is rated 90deg. C static & 70deg. C flexing, you'd need to use the correct glands to terminate the braid though.
Otherwise some flexible conduit with tri-rated singles (105deg. C.)
Pyro would be my choice though.

ETA, due to the temperature, i'd be inclined to run it as a radial using 4mm rather than 2.5 as the circuit should be derated for a high ambient. (my knowledge is 16th Edn./, not current regs so may be wrong).
 
Last edited:
You could use CY LSOH which is rated 90deg. C static & 70deg. C flexing, you'd need to use the correct glands to terminate the braid though.
Otherwise some flexible conduit with tri-rated singles (105deg. C.)
Pyro would be my choice though.
How many trained in domestic installation only, have the ability, and knowledge to terminate PYRO, let alone install it?
 

OneTenner

LE
Book Reviewer
How many trained in domestic installation only, have the ability, and knowledge to terminate PYRO, let alone install it?
Hence my other suggestions ;)
If every sparky was equal, then Pyro would be the only recommendation.
I have seen some right messes made of Pyro - and some pure art, a small church with bare copper Pryo & saddles with black jap screws, lovingly polished by the churchgoers - only let down by some halfwit running some plastic trunking to the boiler 'stat....
 
I've seen and added to MICC in the early 80's, the difficulty was getting the parts. Think the wiring was part-labelled Southampton Electricity Corporation, from 1928 onward. We've moved on a bit, looking like 4mm T&E radial from contributions at present.
 

anglo

LE
Been off-plot for sparkying for some years, but did many rewires, kitchens, etc, before Part P arrived. Just had new GCH installed, ladder principle across the ground / first floor void with 2.4m drops to ground floor radiators.

There's an ugly two-pipe drop into the living room I'm about to box in with 9mm MDF, then paper over the box. Easy. I want to add a pair of two-gang mains sockets, and share the pipe-run box with the 2.5mm T&E. The GCH pipes are 50mm apart, so I'll make the box 100mm.

I've read the rules and interpretations online, no firm guidance there. The T&E is rated at 70 degs C max, and GCH is nominally 60 degs C max when it leaves the boiler 20 feet away. Obviously, that temp will drop after 30 mins and the house is up to heat, but being boxed in, that temp might well hit 60 degs C inside the box. I can stuff the gap between pipes and cables with insulation, or I could vent the box discreetly at ceiling and floor level. The wall is a single pile of extremely hard 2'x2' block, which I'm unlikely to be able to chase out because it supports half the front of the house and I don't have a diamond cutter or the tools to chase.

To the assembly, is this do-able: your views, please?
Why not just use something like,

3093Y 2.5mm² Heat Resistant Flexible Cable White​

up to 90C, for the feed cable for the sockets, it’s protected by the MDF box
you're going to fit over it, or you feed it though some plastic tubing
just make sure it stays as far away from the CH pipes as possible
 

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