IET logo
 
IET
Decrease font size
Increase font size
Topic Title: Just how hot can cables get?
Topic Summary:
Created On: 02 July 2012 10:28 AM
Status: Post and Reply
Linear : Threading : Single : Branch
Search Topic Search Topic
Topic Tools Topic Tools
View similar topics View similar topics
View topic in raw text format. Print this topic.
 02 July 2012 10:28 AM
User is offline View Users Profile Print this message



SKElectrical

Posts: 912
Joined: 01 February 2009

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.
 02 July 2012 11:26 AM
User is offline View Users Profile Print this message



broadgage

Posts: 1359
Joined: 07 August 2007

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.
 02 July 2012 01:21 PM
User is offline View Users Profile Print this message



mikejumper

Posts: 1824
Joined: 14 December 2006

I can confirm that jump leads get hot enough to melt the insulation when they're connected the wrong way around.
 02 July 2012 01:59 PM
User is offline View Users Profile Print this message



AJJewsbury

Posts: 11784
Joined: 13 August 2003

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.
 02 July 2012 11:21 PM
User is offline View Users Profile Print this message



SKElectrical

Posts: 912
Joined: 01 February 2009

Originally posted by: AJJewsbury

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



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

I can confirm that they can set on fire when connected the wrong way round.
 03 July 2012 10:29 AM
User is offline View Users Profile Print this message



markespark

Posts: 87
Joined: 27 November 2010

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 !
Statistics

See Also:



FuseTalk Standard Edition v3.2 - © 1999-2014 FuseTalk Inc. All rights reserved.