New shower installation - couple of questions

[shedssssssss]

9.5kw shower, 10mm TE cable over a run of about 15m, MK Sentry Split load unit (100a / 80a RCD), switched via a crabtree 50a pull switch (neon / mechnical).

1. Considering using an "MK 45A 30mA SP 1 Module RCBO" instead of a 45a MCB on the RCD side of the unit. What are the merits of installing the RCBO over a normal MCB on the RCD?

http://www.screwfix.com/app/sfd/sea...k+45a+RCBO&pn=1&pd=1&pi=1&cn=1&cd=1&x=18&y=14

If i do use the RCBO, where do the two tails connect to? (I assume one is for earth)

I'm presuming the RCBO goes on the non-RCD side of the CU?

2. I'm installing a shower extractor fan / light combination and want this to come on when the shower is in use. What is the best method to achieve this, i've looked at "heavy duty" junction boxes but they only seem to go up to 30a .

 

[Adam_151]

1. Considering using an "MK 45A 30mA SP 1 Module RCBO" instead of a 45a MCB on the RCD side of the unit. What are the merits of installing the RCBO over a normal MCB on the RCD?

When the RCD nuisence trips, you don't have to stumble oput fo the shower naked and with shampoo in your eyes to go and reset the bugger

If i do use the RCBO, where do the two tails connect to? (I assume one is for earth)

The small white one is functional earth and goes to earth, the big blue one is circuit neutral and goes to neutral (both phase and neutral from the shower circuit terminate in the top of the RCBO)

I'm presuming the RCBO goes on the non-RCD side of the CU?

Correct

2. I'm installing a shower extractor fan / light combination and want this to come on when the shower is in use. What is the best method to achieve this, i've looked at "heavy duty" junction boxes but they only seem to go up to 30a .

Probably more hassle than its worth, but ban has a solution involving a contactor and some din rail terminals, personally I'd just have a second light pull cord next to the shower isolator pull cord

 

[HandyJon]

2. I'm installing a shower extractor fan / light combination and want this to come on when the shower is in use. What is the best method to achieve this, i've looked at "heavy duty" junction boxes but they only seem to go up to 30a .

You could get a humidstat extractor fan. The fan will come one soon after starting to have a shower. The light might as well be hooked into the bathroom light switch.

 

[shedssssssss]

Many thanks Adam_151 for the reply. As i've already got a 45a MCB waiting in the CU i'll use that and if trips become a problem consider getting the RCBO instead. I wanted to avoid a second pull switch in the bathroom for neatness sake and was aiming for when the shower was on the light / extractor would all come on together automatically from a single pull switch.

Cheers HandyJon, i'm putting in a humidstat extractor as the main bathroom extractor but wanted a more focused extractor directly above the shower hence the idea of a the light / extractor (with overrun) / shower all powering up off a single switch together.

 

[ban-all-sheds]

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[shedssssssss]

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Very nice, thanks .