dodgy Scottish gas eingineer

[nicsin02]

Hi guys, I have a mate who's shower switch was overheating and could smell burning from it, I opened it up to find the red cable from the load was totally black and I checked connections and they were solid, I knew straight away what the problem was as the shower was only wired in 6mm, turns out they had a 6.5kW shower before but it went faulty and an "electrician" replaced it with a 8.5-9.2kw shower without upgrading the cable???? Anyway the circuit is protected by a 32a breaker which is fine but it never tripped before the cable started overheating for some reason? So I phoned my mates landlord and quoted him for increasing the cable size, renewing switch and upgrading mcb to 40a but he wasn't happy with price so he got an Scottish power electrician out and all he did was change switch and upgraded the mcb to 40a??? If it over heated with a 32a then y the hell upgrade to 40a, he seems legit by leaving a rest certificate with Scottish power headed paper with zs results and signed ect... I'm i missing something? This guy has made job worse? 6mm can't take 40a unless clipped direct which we a know never happens in a house? 6mm to small for size of shower, this post is to prove to my mate that the job is still unsafe so agree with me guys plz, cheers

 

[snowhead]

It's not the cable that's overheated it's the switch contacts or cable connections that have failed thro overheating.
No extra current so no tripping MCB.

 

[nicsin02]

I disagree m8, 40am mcb too big for 6mm cable, cable to small for shower

 

[polo1]

6mm - 32-46 amps depending on the reference method; I tend to agree with snowhead that the heat damage has probably been caused by switch contacts/cable connections rather than overload. Personally though, if I had doubts over how the majority of the supply cable had been run, I would have left it on a 32a breaker, as the likelihood of tripping (even if the shower is 8.5kw) is low.

 

[ChrisElectrical88]

I agree with the other lads. I would have just replaced the switch. I would not have upgraded the MCB. Run the shower on max next time you are there and get you Amp Meter on it if your that worried. Then you can address the landlord if your still not happy.

 

[odawire]

6mm cable/32amp breaker is usually ok for a 8.5 shower as people never put it on full blast coz it would burn you. I agree that upgrading to 40amp is the total wrong thing to do.

 

[ChrisElectrical88]

Exactly, you put a 8.5kW shower on full whack then your not going to be seeing anything but bandages for a few months. With a bit of diversity your well well within a 6mm 32a radial. What is the measured voltage? If it's around 240v then your only pulling around 34A? Max, and that's at full whack. The person in the right here is the geezer who fitted the new shower, unfortunately his switched failed him

 

[sjhall]

Showers pull full load at all times, you can't add diversity... That being said, I would say best option is to replace switch, fit 32a mcb and clamp meter it to see what it's pulling exactly and take from there.

 

[Flanders]

I've see this with cheep pull cords and poorly terminate pull cords, I've always used crabtree one's ,I agree with others if cable has over heated at switch then switch has been poorly terminated , if the cable could not take the load then there would be heat damage at the MCB and the shower, I do agree though that the 40 amp MCB is not going to solve the problem