Twin and earth over hot CH pipes

[thornton_chris]

Hi,

I am replacing my ceiling and have found 1.5mm and 2.5mm twin and earth drapped accross hot CH pipes. Is this acceptable?

The pipes have got lagging on but I am worried they may start to melt.

Am I being overly concerned?

Many thanks,

Chris

 

[ban-all-sheds]

If the lagging is doing it's job then the cables won't come to any harm - have a feel when the pipes are hot and see if the lagging is warm.

But if you can clip the cables out of the way then do so anyway...

 

[darksky]

PVC cable is rated at 70C. Hot water pipes can reach 60-65C.

I would not be happy with wires crossing hot water pipes.

Over time the heat will degrade the PVC insulation.

The local hot spot will derate current carrying capacity of the wire.

In fact I would not like to have a wire cross a cold water pipe.

Services should be separated and where found together it is much better to separate.

 

[JohnD]

if the pipes are lagged with a modern polyethylene foam, the temperature at the surface of the insulation will be much lower than 65C. If there is an air space as well the cable is unlikely to be at all hot.

check the quality of the insulation and renew it if not good. If there is room you could use the better BS grade of Climaflex which is very thick and will cost about £1 a metre from your DIY shed.

you can tuck a thermometer under the floor and see how warm it is, but if the cable is not actually in contact with the hot pipe it will not be damaged.

it is true that the life of PVC cable insulation reduces in warmer conditions.

 

[toasty]

central heating pipes, especially the flow pipe can reach 80C, depending on boiler setting.

With insulation in between I wouldn't worry, but without it I think it is only a matter of time...
-Dan