HELP: What AMP should RCCB/MCB For Electric Shower ?

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Does the AMP rating of the MCB fitted with in a RCCB have to match up exactly with the showers AMP rating or can it be higher ?

For instance when fitting a 8.5KW 40A shower can I safely use a RCCB with a 50A MCB or does it have to be 40A rating ?


I would really appreciate a firm reply ASAP as i need to place the order tonight if possible.

Thanks


Archy
 
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The MCB does not have to match the rating of the shower, but it must be equal to or below the current carrying capacity of the cable fed from it. Don't just install the MCB with out considering the cables used.

A 40A MCB and suitable cable is required.
 
davy_owen_88 said:
The MCB does not have to match the rating of the shower, but it must be equal to or below the current carrying capacity of the cable fed from it. Don't just install the MCB with out considering the cables used.

A 40A MCB and suitable cable is required.

Thanks for the very clear reply Davy & thanks to you also Tim.

I wanted to fit a 9.5KW electric shower & use RCCB unit as my main consumer unit is fully populated. I was thinking of using 10mm cable & the RCCB that comes with a 50A MCB as opposed to 40A MCB. WIl this cable be sufficient for the 50A MCB ? Or is the 40A MCB adequate for the 9.5KW shower ?
 
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10mm² t&e has a current carrying capacity of 64A when clipped direct with no de-rating factors.

What route will the cable take? Will it go through any insulation? Be run in conduit/trunking? Run through any area with a high ambient temperature?
 
The main consumer box is under the staircase & bathroom is above & a little further back from it. I have not yet figured out the best path to take as yet.
Maybe through cavity of outside wall to roof ceiling than back down into shower point in bathroom.

BTW: To connect the RCCB unit from the main will i need some kind of distributir/splitter ?

This is the unit i plan to buy: http://cgi.ebay.co.uk/50a-Shower-Co...ryZ57215QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
 
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Remember that standard twin and earth is not suitable for outdoor conditions so will need to be run inside conduit if you plan on running it outside (this will reduce the CCC though).

For such a high load you should feed the CU directly from the tails using something like this.

Remember that if you are doing this work yourself that you must notify your BCO before you start the work.
 
I will not be doing the work myself but will get a professional to do it.
I just wanted to be able the buy the correct parts & know what work is involved so I don't get cought out by a cowboy.

Just to clarify one last point please: Will 10MM cable be ok for a 9.5KW shower using a RCCB with 50A MCB or do i need to step up to heavy duty 16mm ?
I can feed the cable from CU though wall cavity to roof ceiling or take it direct through the stairs & into bathroom.
 
If you are wanting a professional job, let the pro buy the parts. I don't know about that particular brand of CU but it looks cheap, I'd probably end up drop testing it.
 
Spark123 said:
If you are wanting a professional job, let the pro buy the parts. I don't know about that particular brand of CU but it looks cheap, I'd probably end up drop testing it.

Well shouldn't all electrical units sold in UK conform to certain regulations ?

I don't necessarily want to pay for brand name or looks. As long as it can do the job & meet safety standards its good enough for me. And to be honest it's not not so easy to distinguish real professionals from ones who think & make they are. I believe the skill standard in the UK was much higher in the past than it is today - bit like the 'o' level & gcse comparison. I would much rather trust an old school plumber/electrician any day than today's qualified ones. So I like to do what I can to ensure the job is done within my budget & to the correct standard rather than just blindly hand over a wad of money to someone with a certificate. I don't believe in being ignorant.

Still looking for answer to this one please:

Will 10MM cable be ok for a 9.5KW shower using a RCCB with 50A MCB or do i need to step up to heavy duty 16mm ?
 
you appear to have chosen the cheapest possible import, with no recognised brand name.

Would you buy an unbranded TV off a market trader? Or a Somali-built motor car with no guarantee?

Do you expect a professional electrician to warrant his work if you try to make him install rubbish that belongs in the bin?
 
archy121 said:
I would much rather trust an old school plumber/electrician any day than today's qualified ones

Not always the best decision, there are good and bad in all generations of tradesmen ;)
 
ricicle said:
Not always the best decision, there are good and bad in all generations of tradesmen ;)

True. But that's just my opinion based on experience in dealing with plumbers/electricians.

JohnD said:
you appear to have chosen the cheapest possible import, with no recognised brand name.

Would you buy an unbranded TV off a market trader? Or a Somali-built motor car with no guarantee?

Do you expect a professional electrician to warrant his work if you try to make him install rubbish that belongs in the bin?

Aren't you getting rather worked up & personal about my opinion ?
Some might take your Somali example as being on the fringes of being racial.
 
archy121 said:
Well shouldn't all electrical units sold in UK conform to certain regulations ?

Should but not all imported items do conform. Built as cheaply as possible and often the production standards slip below the standard of the carefully produced items sent to the testing laboratory to get type approval.
 
archy121 said:
I will not be doing the work myself but will get a professional to do it.

rofl5.gif
 

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