connecting a shower consumer unit.

[the scriv]

i have fitted a new 9.5kw shower and run 10mm twin and earth, i am just about to fit an external 63A 30mA Rcd with a 50A MCB.
My question is can i come straight out of a spare 40A MCB on my board with my live and them into the RCD and get my Neg and Earth from the buzz bars within my Consumer unit. Obviously this would be in 10mm.

 

[dw3101]

No, 9,500w @ 230v is 41A

hence fitting the consumer unit, you need to use 16mm tails (min, 16mm are easier in the tiny CU's) And take these to a Henley Block (its like a large Junction box in the meter tails)

 

[ban-all-sheds]

Do you not think that maybe you've missed out a few important things in that answer, like dealing with the working-with-live-meter-tails problem, and the issues surrounding pulling the service fuse?

 

[the scriv]

Thankyou for your responses to my question.
The reason i suggested taking the live from my 40A mcb inside my Consumer unit and then my Neg and Earth from the buzz bars was due to the fact that this then got around the need to play with live tails and or pulling the service fuse. I could isolate my main breaker on my board and work safley.
As regards my shower pulling 41A could i not simply just increase my mcb to 45A and then go into my external shower consumer unit. I would still be using 10mm cable.

 

[dw3101]

yeah, I cant include everything..like equipotential bonding...

nor did I point out the problem with 'live and neg' and the supply being AC and not DC.

David

 

[ban-all-sheds]

Thankyou for your responses to my question.
The reason i suggested taking the live from my 40A mcb inside my Consumer unit and then my Neg and Earth

Neutral & earth

from the buzz

bus

bars was due to the fact that this then got around the need to play with live tails and or pulling the service fuse. I could isolate my main breaker on my board and work safley.

Indeed, and that would be the best way to do it.

As regards my shower pulling 41A could i not simply just increase my mcb to 45A and then go into my external shower consumer unit. I would still be using 10mm cable.

Check the small print - many manufacturers quote the rating at 240V, not 230V, in which case your 9.5kW shower might draw just under 40A (and only be about 9.1kW at 230V).

 

[sclement]

Hi

I did pretty much the same when I installed a Mira 9.0 kW shower last year and it is all up and running.
Used a 30 mA RCD between the 40 A MCB in the consumer unit (I was limited to this as this was the maximum current MCB that was available for my consumer unit) and the DP swicth in the bathroom.

The RCD was part of a shower consumer unit which also incorporated a 63 amp MCB. It was cheaper to buy one of these than the 30 mA RCD on its own.

Worst bit was routing the 10mm cable.

I did not really fancy working with live meter tails or pulling the service fuse also.

 

[ban-all-sheds]

Worst bit was routing the 10mm cable.

Great fun, isn't it.

 

[plugwash]

has anyone ever tried using split con for wiring showers?

 

[ban-all-sheds]

I was going to use SWA so that I could run the cable up the outside wall from under the stairs up to the loft, but then I decided I could run the 10mm² internally after all.

I also implemented the plan of using a contactor energised by the shower circuit to switch a feed from the lighting circuit for the fan - works a treat.

 

[securespark]

Got a call-out to a "fault" the other day.

The guy has a wet room with a shower for his wheelchair-bound missus and he swears that when you switch on the shower, it triggers the fan. Trouble is, I cannot see any evidence of wiring to support this. He is going to ring the installer to clarify....

 

[plugwash]

could be a humidistat fan?
i can imagine that would trigger pretty damn quickly in a wet room if a shower was used.