cable identification(shower)

[saint elmo]

hi im redoing the bathroom and the 9.5kw shower is on this cable which has burnt at the connector block at some point its on a B32 MCB

im not sure what size this cable is, measuring the cable width it looks to be 6mm2 measuring the conductor looks to be a 10mm2

the diameter of the individual conductors is between 4-5mm

the width of the overall cable is about 14mm

the earth is significantly smaller, slightly thicker than a 2.5mm2 conductor

pictured next to 2.5mm2 cable for comparison

when i put everything through the IEC calculator it says the earth size should be the same as live and neutral cable wrong anyway?

 

[littlespark]

With twin and earth cable, the cpc (earth) is smaller…. Perfectly ok.

I would say it’s 6.00mm as it’s a solid cpc (2.5mm size)
With 10mm, the cpc is stranded (4.0mm size)


just curious, but where was that connector block?

 

[saint elmo]

part of the shower

 

[saint elmo]

With twin and earth cable, the cpc (earth) is smaller…. Perfectly ok.

I would say it’s 6.00mm as it’s a solid cpc (2.5mm size)
With 10mm, the cpc is stranded (4.0mm size)


just curious, but where was that connector block?

^^^

 

[Mikegh]

Looks like 240v 9.5 shower so breaker is undersized probably

 

[saint elmo]

Looks like 240v 9.5 shower so breaker is undersized probably

yea im in the UK so 240v in reality 230v in theory.
breaker is undersized and by the sounds of it the cable too

 

[Mikegh]

2nd pic of burnt out terminals recently

Common problem

I reckon plumbers and DIY are responsible for most of it, most trained sparks know to tighten the connections

 

[littlespark]

I just find it strange that a plastic connector is screwed down like that…. And I know that’s the way everyone does it.
Metal screw possibly cutting into the plastic, reducing the insulating material and creating a weakened path between the live copper and the cpc through the screw.

Not the problem here, I should add.

This is simply a loose connection causing heat

 

[Mikegh]

I was curious was that the original terminal block

 

[saint elmo]

I was curious was that the original terminal block

yes its the original i looked at plumbing spares for the model and they want over £18 for a new one!

 

[saint elmo]

so can anyone else confirm this to be a 6mm cable?

 

[timhoward]

I’m 99% sure it is looking at that, as above comparing the 2.5mm cpc with the 2.5mm T+E it looks spot on.

(If you have a micrometer you can just halve the measurement of a single strand, multiple by itself then PI, then by the number of strands (usually 7) to double check.)

 

[Mikegh]

Almost certainly by the looks of it

 

[littlespark]

Just a thought…. Have a look on the grey sheath of the cable, it sometimes has the size marked into it

 

[LukeD]

I have a thing about electric showers. I dont like using them and would never ever have one

 

[DPG]

I have a thing about electric showers. I dont like using them and would never ever have one

Lol. Is there a name for such a fear?

 

[Pete999]

Just a thought…. Have a look on the grey sheath of the cable, it sometimes has the size marked into it

Instead of mucking around cutting strands etc, try and work out the cable route distance, measure the resistance, look in the OSG or 7671 and check th /e mili ohm per meter and work it out from that. just a thought.

 

[Mikegh]

There was at least a couple of deaths here (Ireland) back in the day but they were badly installed

 

[DPG]

Instead of mucking around cutting strands etc, try and work out the cable route distance, measure the resistance, look in the OSG or 7671 and check th /e mili ohm per meter and work it out from that. just a thought.

If he doesn't know whether a cable is 6mm or 10mm then I suspect he's not going to have a copy if BS7671 and an Ohmeter. I don't think the OP is a spark Pete.

 

[Pete999]

If he doesn't know whether a cable is 6mm or 10mm then I suspect he's not going to have a copy if BS7671 and an Ohmeter. I don't think the OP is a spark Pete.

He says he is a trainee electrician

If he doesn't know whether a cable is 6mm or 10mm then I suspect he's not going to have a copy if BS7671 and an Ohmeter. I don't think the OP is a spark Pete.

The OPs profile says he is a Trainee Electrician and has 2365 so deductions would say he should own or have accessv to BS 7671 BUT YOUR POINT IS A VALID ONE