I was called to a job yesterday where there had been a problem with the boiler. In short, a room filled with very very very hot steam, plastic pipes warped , trunking warped, drline boxes warped, fire door seal expanded etc etc
A guess was made that temperature got to 100 - 120 degrees celcius.
So my question is.. will the twin and earth cables be okay? they feel a bit soft but IR is good. Also an FP gold which also feels very soft.

In my view the cables are probably OK, but I would replace them just in case. I dont think that "probably OK" is an accepted term where electrical safety is concerned.

Fully loaded cables can run at about 70 degrees, and should survive the odd fault that makes them hotter still before the OCPD operates, so they are probably OK.

I would be as concerned about water damage, steam may have spread suprising distances via conduit, trunking or openings in the building fabric, and then condensed in undesireable places.

I can confirm that jump leads get hot enough to melt the insulation when they're connected the wrong way around.

Table 43.1 seems to suggest that PVC cables should survive up to 160 degrees - but only for a very short time - <5s.

I would imagine that there's a risk of the softened insulation sagging from around a conductor leaving a thinner section at the top - perhaps snip a couple of likely candidates to see if it looks at all odd in cross section.

Gut feel is to replace if in any doubt though.
- Andy.

Probably stayed at over 100 celcius for more than 24hrs.
Anyway they've called another electrician, so not my problem. I would have replaced the cables (one 3 core and earth had shorted but im guessing it was already partially damaged).




I can confirm that they can set on fire when connected the wrong way round.

I had a similar experience with a faulty boiler - went to the job to find it had acted as one huge wallpaper stripper with all of it laying on the floor - one of the funniest things I'd ever seen !