CU change for assessment

[bodders22]

Hi Guys, Hope you can help. I'm doing a cu change on my grandads house for my elecsa assessment next friday. The problem is theres a 9.5kw shower with a 6mm cable, the run is about 9 meters partly ran in surface conduit partly clipped direct(in an airing cupboard). The shower has been in for about 7 years with no signs of damage to the cable,switch or shower. Do I have to change the cable to 10mm or can it stay as it's an existing circuit. If it can stay what size mcb 40a or 32a ? thanks in advance.

 

[Jimmyb]

Most of shower are worked out @ 240volt for sales purposes which if worked on this it needs 39.6 amp. If done @ 230 which is what we should work on then the amps are 41.3 you need to really check current draw with clamp meter to verify.

6mm cable will not be bigger enough because the fact that it is run in conduit and it is also in a hotter place (Airing cupboard) if not for these reason i would say 40a mcb on 6mm but i would install a 10mm and keep it on a 40mcb otherwise you could be looking at a 16mm.

 

[telectrix]

put a clamp meter on the 6mm with shower at various settings, i would be extremely surprised if it pulls more tha 35A at most. most manufactures over rate the showers. i've seen 9.5kw running on 30A MCBs with no trouble. personally, i would leave the 6mm in .

 

[bodders22]

Thanks guys but how would i stand for my assessment if i leave it in (its my first and want to get it right) bearing in mind i wont be getting paid for cable or work as its a freebie so i can use the house for my assessment

 

[tonys]

Thanks guys but how would i stand for my assessment if i leave it in (its my first and want to get it right) bearing in mind i wont be getting paid for cable or work as its a freebie so i can use the house for my assessment

What size protective device is the shower on at the moment?

 

[telectrix]

as i said, first measure the current drawn. if it's under 40A, 6mm on 40A MCB is fine. mention to assessor that you have raised the issue as borderline with the client. bear in mind, it's the CU change you are being assessed for: by pointing out a possible concern with the existing shower wiring, you are showing understanding. BTW, GOOD LUCK .

 

[bodders22]

Hi tonys, the shower at the moment is on a 30a wylex rewirable

 

[SirKit Breaker]

You are on the border with 6mm, but i dont see any problems. Put it on a 32a MCB, and make a note something to the effect of recommend upgrade of 6mm cable to 10mm in the near future.

The 32a type B MCB will run in over current for much longer than it takes the average person to have a shower, and so will the cable short term anyway. The thing most likely to fall over will be the pull switch.

Cheers.......Howard

 

[tonys]

Hi tonys, the shower at the moment is on a 30a wylex rewirable

Can you not get your hands on a Wylex 32Amp push in MCB to see if its holds up? or fit the new cu and put it on a 32Amp MCB to see if it holds up?

 

[bodders22]

Yes , i'll try it on a 32a mcb when i change board tomorrow(hangover permitting!) so is the general opinion that if it holds and i make a note on the eic that i recommend a cable upgrade in the near future the assessor wont fail me (on this at least!). My assessor is Richard Giddings from elecsa anyone had him before whats he like?

 

[tonys]

Yes , i'll try it on a 32a mcb when i change board tomorrow(hangover permitting!) so is the general opinion that if it holds and i make a note on the eic that i recommend a cable upgrade in the near future the assessor wont fail me (on this at least!). My assessor is Richard Giddings from elecsa anyone had him before whats he like?

If it operates on a 32Amp MCB that's fine, so no need to make any notes imo.

 

[ezzzekiel]

as stated you are replacing cu the shower is not your concern, carry out usual tests and note results, if the shower circuit fails disconnect it and state why, if it passes all tests leave it alone but write up your observations on the Eic, your covering your back, that way if any future problems you have the evidence that it was brought up but you were refused the go aheah for any additional works.

 

[Jimmyb]

6mm cable ok, what about the installation conditions ??????

 

[telectrix]

6mm cable ok, what about the installation conditions ??????

on original post. it is in conduit and clipped direct.

 

[Dec]

Hey Bodders, How did the install go?