shower cable and switch

[sbelec]

Hi guys, like to just get your opinions on a shower I am going to cable.

I am putting in a shower feed 10.5kW, no problem 10mm with 40/45 amp MCB and rcbo but this becomes my problem. Preferred solution would be RCBO in existing box or MCB in existing box and additional RCD box outside. I am trying to get schneider to commit to suitable rcbo/MCB for Merlin Gerin box but this is painful. Alternative is to run cable from out going side of existing consumer unit main switch (then main switch in this CU would turn off all power to house) to a seperate dedicated RCBO feeding shower, my thought is that I could use 10mm cable and the RCBO would be protected from overload by the RCBO - any thoughts?
Can't use Henly blocks as tails comes through wall in steel and existing consumer unit is 3 inches from corner of 2 walls so no route for new cables or room to add Henly blocks (my normal preferred method). This is a well installed ground floor flat with NO absolutely thought to maintainence.

Also, any reason why I cannot put the shower switch in the airing cupboard? The little room is off the bathroom with its own door, the switch would physically be behind the shower and easily accessible with door open. Don't see a problem as it would be no different to putting the switch outside the bathroom. I can't use pull switch as no access into ceiling space.


thanks guys for sensible thoughts...

 

[decolad69]

Upgrade CU ?

 

[Andy78]

What type of Merlin Gerin board is it ? shouldn't be too hard to get something to match.

 

[sbelec]

CU (and flat) is about 12 years old and is of metal construction, more of the industrial syle and it appears to have been "plastered in" so it looks like part of the building fabric plus cabling is very short so it would not be a simple swop and I could imagine plastering / decorating the works. Seriously doubt if the customer would go for it, i wouldn't.

 

[hasel5]

Repeat thread?

 

[decolad69]

CU (and flat) is about 12 years old and is of metal construction, more of the industrial syle and it appears to have been "plastered in" so it looks like part of the building fabric plus cabling is very short so it would not be a simple swop and I could imagine plastering / decorating the works. Seriously doubt if the customer would go for it, i wouldn't.

If it's a multi 9 MCB you will find, I think, the older MK sentry may fit.

 

[Andy78]

If it's a multi 9 you can still buy them.

 

[sbelec]

What type of Merlin Gerin board is it ? shouldn't be too hard to get something to match.

I took all the details down and e-mailed schneider, apparently I missed something, so going to go back for second look. Marked multi 9 and schneider do a multi 9 ut there are 2 versions!
Always very wary of not getting CU manufacturers approval given the reason missives on "the integrity of the CU can be compromised if wrong MCB fitted" brigade. Never understood why 2 BS standard components of the design are not interchangeable - that could be a long thread....

 

[Andy78]

What does it say on the existing breakers ? Chances are the MCB code will be C60H. Schneider branded C60H are readily available, but not cheap.

 

[sbelec]

Seen 2nd hand but after schneider comment of 2 different types need to get one fully out. But will have another look.

Using a different make is the question mark and brings in this question of cu box integrity.

 

[sbelec]

Any thoughts on coming off the switch / cable size and location of switch?

 

[Andy78]

My thoughts on bodging a cable into the busbar side of the main switch ?
Don't !

I am pretty confident you will be able to get MCB or RCBO to fit this board. Whether you go for a RCBO or MCB and external RCD will be your choice depending on cost. I paid £7 for a multi 9 MCB a couple of weeks ago, and I know Merlin Gerin RCBOs used to cost around £70.

 

[Guest55]

Any thoughts on coming off the switch / cable size and location of switch?

seems reasonable , done it myself when other options are thin on the ground.
10mm t&e from CU sw to rcbo , current through t&e limited by downstream rcbo , crack on.
Murdochs tin hat on.
;-)

 

[sbelec]

My thoughts on bodging a cable into the busbar side of the main switch ?
Don't !

Without being disrespectful, why? What is the difference between this and the split cables of a high integrity board where a cable is fitted with the busbar.

My priority is to find an MCB, it was just a back up plan.

 

[Andy78]

Without being disrespectful, why? What is the difference between this and the split cables of a high integrity board where a cable is fitted with the busbar.

My priority is to find an MCB, it was just a back up plan.

The only difference really is that the cable in a split CU doesn't wander off into another enclosure. It's just not something I would do. Just working practices really. But like Biff says, when options are thin..........

 

[sbelec]

Understand that and certainly not my preferred option. I would fit second box within a couple of inches and enclose cable but it is backstop.

 

[sbelec]

As a footnote to this the existing MCB is multi 9 45n, schneider have responded that the H60C will fit with a "BCL" adaptor. H60C is not bad on price but the BCL comes in 10's at £30 and I need 1!!!

Many thanks for your input.