shower

[gooner1984]

im about to change a cu for a friend for my assessment with napit, the only thing worrying me is a 7.5kw shower is on a 32a CB and is wired in 4mm2 twin and earth i no it ant right, but not sure what to do do i take it out of use, or do i tel my friend that its best to run say 6mm or 10mm, some advice would be great

 

[rocker]

It's OK on that

 

[nickblake]

Generally shower cable is 6 or 10 mm , as its a low power shower then 4mm may well be big enough this depends on installation methods insulation etc i would prefer a 6 or 10 mm but its 7.5kw you can use 4mm on a 32 amp mcb as it draws that 7500/230 = 32.6 amps so depending on installation methods, think its an A2 Radial circuit you'll find it in the on site guide table 8A page 158

 

[gooner1984]

yeah mate its A2, its run in conduit all the way up to switch plate

 

[rocker]

If they do pull you up on it, just say to the best of your knowledge the cable was installed to reference method C - clipped direct and plastered directly in walls.

EDIT yep cond is fine too, 32A

 

[gooner1984]

thanks mate just wanna make things go smooth bricking it as it is

 

[rocker]

That's perfectly natural lol

 

[Geoffsd]

i no it ant right, but not sure what to do do i take it out of use,

You are correct.
If I were you I would disconnect from CU. Tell the assessor that you are going to replace with 6mm².

The assessor's chief concern with your work will be SAFETY. It won't look good for you if he sees it like it is.

Good luck.

 

[rocker]

Geoffsd, what are you basing this on? The cable will take in excess of 32A, the protective device will activate at 32A. Where's the concern?

If you tell the assessor you are going to replace with 6mm, he is going to ask you why, and wonder why you haven't bothered reading the regs for your assessment.

 

[telectrix]

if you've got a clamp meter, measure what the shower is actually drawing. bet it's under 30A!

 

[Geoffsd]

4mm² T&E in conduit (method B) is rated at 30A which is, I presume, why gooner is asking.

This is exactly the sort of thing the assessor will be looking for.
When, not if, he notices the cable then the conduit he will then wonder and ask where else it goes - through insulation in the loft?
It's not much but 30 is not 32 and, like speeding, there's no argument.

It would be a pity if gooner fails because of something he knew was wrong.

 

[topquark]

How long is the cable run?

 

[Des 56]

You have more faith in the ability of these assessors than me, if you think that they will instantly see a 4.0mm cable not a 6.0mm or whatever and begin asking questions about installation reference methods and whether it complies or no

They do a regimented and very basic inspection of the install that has been lpresented and are more concerned with the ability of the candidate than the installation compliance

Some of these assessors also come up short on assessor abilities as well

In the end, the money that has been paid, and will continually be accounted for by the scheme ,is the all important entry requirement



Cynical ? Yes I am

 

[Geoffsd]

But does gooner, or would you, want to take the risk?

 

[Des 56]

Well a 4,0mm radial on a 32 amp mcb is a standard circuit
He is changing a consumer unit,not installing the circuit
The initial design of the circuit was not his,the routing of the cable that will determine the reference method and the current carrying capacity of the circuit was that of the designer
He can only go on test results being satisfactory
You are unlikely ever to know what route and reference method applies without the designers information
The 4.0mm on a 32 amp will present no risk to his assessment
If he is concerned,do what as been suggested by others and disconnect the circuit for that assessment