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Discuss UFH T&E Cable Melting / Heat Damage in the Electrical Forum area at ElectriciansForums.net

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I was tracing some electrical cabling last night and noticed a ~6" section of 2.5 T&E cable that appears to have been subject to heat damage and the plastic has started to melt. It's about 1m away from the CU in the garage and connected to a 32amp MCB. It's a radial circuit that powers a small 4 sqm section of UFH int the utility room. I have no info on UFH as it was installed before we bought the house. Luckily we never really used it.

So from what I can see the circuit looks something like this:

32 Amp MCB (Contactum B Type) --> Damaged section of cable --> Switched fuse on garage wall --> into wall cavity --> Once it goes into the wall cavity i have no idea where it goes.

Needless to say, I've isolated the circuit at the breaker and won't be turning back on until an electrician has advised and fixed. There's a second identical circuit that provides power to the UFH in the kitchen. I've also isolated this despite there being no visible damage.

I'm interested to see what you guys think the problem is. Did the MCB fail or is 2.5 T&E no suitable for a 32amp circuit? Do you think there's a fault with the UFH or maybe just a faulty run of cable?

One good outcome from all this is that it's made me realise i need a fire alarm and CO2 extinguisher in the garage.


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B

Bobster

I would say that damage is actually caused by a plumbers blow torch.

With the PVC turning white like that, it's been exposed to a very hot heat for a short period of time.

The cable has been burned from the outside.

Edit:

A 32amp MCB isn't ideal for the situation. However not against the rules as it is a fixed load. Providing it meet other circuit tests that should have been completed on installation. I can't see UFH being anything other than a resistive load, so little to no inrush when powering up.
 

DPG

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Advent Win
Is it possible that the plumber did it with his blow lamp? It's very close to the soldered joints, and the damage appears to be at the bottom edge only.

If not then it's very very localised, and could possibly be e a cable fault.
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Rob got there before me. Only by seconds though - I'll get there next time!
 

Spoon

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I'd go along with @Rob post above.
 

telectrix

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agree with both above posts. deffo the wet-pants has been let loose within a mile of the cables. recipe for disaster. having said that, a 2.5mm radial circuit should be protected by a MCB <25A.25A MCB is not common, so a 20A or a 16A is usual. 4sq.m of ufh is generally < 1kW, so even a 10A would suffice.
 
  • Thread Starter Thread Starter
  • #6
I think you're both right. Hadn't even considered that. I had a new boiler fitted over the winter and the plumber needed to replace the existing pipe work with a wider diameter pipe. What an idiot. He'd have definitely noticed that but chose not to say anything. I couldn't stop him banging on about the importance of Gas regulation and health and safety.

So I guess the good news is i just need to replace the stretch of damaged cable.

Thanks guys
 

DPG

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You would have thought he'd have put a heatshield over the cables. And yes, he would have noticed the damage and not said anything - very disappointing. I'd show him the damage to be honest - you should at least ask for your first boiler service to be done FOC.
 

telectrix

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plumbers have limited vision. they can't see anything apart from their pipes and the fact that sh!t flows downhill.
Post automatically merged:

tell the wet-pants to invest in 1 of these:
1566989163584.png
 
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  • Thread Starter Thread Starter
  • #9
You would have thought he'd have put a heatshield over the cables. And yes, he would have noticed the damage and not said anything - very disappointing. I'd show him the damage to be honest - you should at least ask for your first boiler service to be done FOC.
No way he's coming back. I'll just make sure the local community know what he's capable of.
 

Spoon

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plumbers have limited vision. they can't see anything apart from their pipes and the fact that sh!t flows downhill.
Post automatically merged:

tell the wet-pants to invest in 1 of these:
View attachment 51706
Don't they have some heat proof material for instances like this. (You know what I mean... :tearsofjoy:) Some think that protects the surrounding area...
 
B

Bobster

If the cable runs to a switch fuse on the wall of the garage, an is all surface as the photo. Wouldn't take an electrician more than an hour to replace for you.

Being in London though, you could be looking at a little bit higher cost involved, especially if there's no parking nearby, congestion zones etc etc...
 

Spoon

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You would have thought he'd have put a heatshield over the cables. And yes, he would have noticed the damage and not said anything - very disappointing. I'd show him the damage to be honest - you should at least ask for your first boiler service to be done FOC.
Sorry mate. I must have missed your post or I wouldn't have posted a similar post.
I gave you a 'love' rating, hoping for forgiveness..
 
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  • #13
Out of curiosity, is replacing the cable myself in breach of any regulations? Looks pretty straight forward.
 

DPG

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Arms
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Advent Win
Out of curiosity, is replacing the cable myself in breach of any regulations? Looks pretty straight forward.
I personally think this is a job which could be done by a competent DIYer, but others may disagree. See what opinions you get.
 

Spoon

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Out of curiosity, is replacing the cable myself in breach of any regulations? Looks pretty straight forward.
Why are you offering to replace it mate?
If a car smashes into your car would you offer to fix your own car or get the person who caused the damage to pay for it?
 
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