New Shower

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At the risk of incurring much wrath over Part P (who told the great British public that their ability to do their own thing in their own castle was to be removed ?)some advice would be welcomed. I have changed a normal bath for a whirlpool and connected the motor to the twin earth 6mm feed from the consumer unit (fitted with Memshield 2 RCCB 63A - was the feed for a 8Kw shower). I am now putting in a new 10.5KW shower. I am using twin earth 10mm and going back to the same consumer unit. Am I correct in believing that I can connect to the same Memshield 2 RCCB? It is a Memera 2000 unit.
 
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breezer said:
you will have to remove your connection for your pump!

He could use a spur from the shower feed that is appropriatly fused down. This would be perfectly acceptable as the shower and the bath are unlikely to be used simultaneously for one, and secondly the combined loading would be within the operating characteristics of the cable and the protective device.
 
i was thinking more along the lines of the 10mm cable, he would have to use that to feed an fcu
 
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Thank you FWL_Engineer and breezer. I am a little confused. What I had intended was to take the 10mm from the shower back to the rccb and the 6 mm from the pump to the rccb. There will not be an occasion when both would be used together.
However, what I think you are suggesting is that I take only the 10mm back to the rccb and connect the pump via a spur using 6mm cable. Is this correct. I assume I would want some form of switch so that I could ensure that only the shower or pump could be used at one time. If this is correct what sort of switch and where would I have to position it?
 
cjashower said:
6mm feed from the consumer unit (fitted with Memshield 2 RCCB 63A - was the feed for a 8Kw shower).
Never mind the RCCB, what's the rating of the MCB?

I am now putting in a new 10.5KW shower. I am using twin earth 10mm and going back to the same consumer unit. Am I correct in believing that I can connect to the same Memshield 2 RCCB? It is a Memera 2000 unit.
No, you are not correct - firstly you aren't connecting to the RCCB, you are connecting to the MCB, and secondly whatever was there for an 8kW shower on a 6mm² cable will not do for a 10.5kW shower.

cjashower said:
Thank you FWL_Engineer and breezer. I am a little confused. What I had intended was to take the 10mm from the shower back to the rccb and the 6 mm from the pump to the rccb.
No - this will not do at all - after you've replaced the MCB with a 45A one for the shower the protection will be inadequate for a 6mm² cable.

I think you need to read this: //www.diynot.com/forums/viewtopic.php?p=81696#81696

what I think you are suggesting is that I take only the 10mm back to the rccb and connect the pump via a spur using 6mm cable. Is this correct.
You don't need 6mm² to supply the pump - it probably only draws a few amps. What is it rated at?. You do need the supply side of the FCU to be fed via preferably 10mm², but a short length of 6mm² in free air where it is unlikely to be disturbed would do. But have you thought about how and where you are going to join 2 x 10mm² or a 10mm² & 6mm² cables together? You'll not get both into the same terminals of an FCU....

I assume I would want some form of switch so that I could ensure that only the shower or pump could be used at one time. If this is correct what sort of switch and where would I have to position it?
You don't need a switch - as you said, they won't be on together, and even if they are, the additional load of the pump is probably of no importance. If you do want one, you'll need a DP changeover switch rated at at least 45A, positioned in Zone 3 or outside the zones, but be warned - they don't look too good from a domestic decor POV...

Are you sure that you know enough to be doing electrical work?
 
woahh. Lets not get muddled up.

The shower needs to be on 10mm, and a 40 or 45A breaker (check the instructions). The RCCB on its own is only part of the story - it may well be quite capable of feeding two circuit breakers, one large and one small, for shower and pump respectively, but where does it get its supply from - is ther already a breaker or fuse upstream ?
The pump, which will be a few hundred watts, could likely share the shower cable, but it is unusual, and as it could be fed from just about anywhere, but WILL need its own fuse or circuit breaker of appropriate size. (check the instructions or read the motor rating plate and add a margin for inrush)
hope that helps clarify what is suddenly getting very cloudy.
 
Decided to install the shower first. Used 10mm and connected to the RCBO with a 45A MCB. Works perfectly.

This now leaves me with the requirement for connecting the whirlpool that will not be in use at the same time as the shower - ever.

I am attracted to the idea of a DP changeover switch that I could locate in the airing cupboard that is outside of the bathroom as suggested above. Anyone care to point me at a suitable product and supplier. The whirlpool is connected to the 6mm used by the previous shower (seemed a waste not to utilise what was already in place). Accept that a DP switch may not be elegant but hidden in a cupboard we are not too bothered by looks.

Grateful for help so far and future suggestions.
 
Thank you for pointing me in the right direction. I appreciate I'll have to go to a 63A version but can anyone suggest a slightly cheaper solution - the house is costing a fortune to refurbish!
 
cjashower said:
Thank you for pointing me in the right direction. I appreciate I'll have to go to a 63A version but can anyone suggest a slightly cheaper solution - the house is costing a fortune to refurbish!


you could use a 2 way light switch, mind you it will over heat, catch fire, burn house down, ahh, but it was cheaper.

do not take any chances, as with most things quality costs, houses are also not cheap.

also think how much you are saving by asking on these forums, you should be paying us. buy the suggested switch
 
Bought the switch as suggested. Now fitted and working. Thank you very much for your assistance and advice.
 

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