swapping a 30 year old electric shower.

[Fredstudio]

Hi I have been to look at swapping a electric shower that is about 30 years old. Can I swap this like for like same kilowatt shower. The fuse board is an old one, I think with one single fuse doing the whole house. So I am guessing there is no rcd protection on the shower circuit. I am a plumber by the way not an electrician.

 

[sparkwright]

You would be very wise to make sure you have an RCD protecting the shower.

It would also be sensible to check that the wiring and fuse or circuit breaker IS the correct size.

If in doubt, send pictures if you can.

 

[Fredstudio]

Thanks can I ask what rcd's do?

 

[winston1]

RCDs detect an unbalance in the supply usually caused by leakage to earth (through you possibly) then trip the supply.

Modern showers seem to be higher power than old ones which were 6kW max. The wiring, fuses, etc may not be suitable for modern ones, around 8.5kW.

 

[JohnW2]

Thanks can I ask what rcd's do?

I don't know how technical an answer you want, but the basic idea is that they may stop people dying - by disconnecting the electricity supply if there is a fault which could, or does, result in their getting a shock. Situations in which electricity, water and wet naked human beings come into close association clearly have their hazards.

Kind Regards, John

 

[Fredstudio]

RCDs detect an unbalance in the supply usually caused by leakage to earth (through you possibly) then trip the supply.

Modern showers seem to be higher power than old ones which were 6kW max. The wiring, fuses, etc may not be suitable for modern ones, around 8.5kW.

Thanks are you saying its possible the shower could be fed of less then 6mm cable with it being so old.

 

[Fredstudio]

Would it be a huge job to add an rcd with it being an old fuse board. And is it a must that the new shower needs one?

 

[flameport]

Would it be a huge job to add an rcd with it being an old fuse board. And is it a must that the new shower needs one?

Not usually a problem to add an RCD - typically a separate RCD would be added just for the shower.

Manufacturers instructions and BS7671 both require RCDs for electric showers - ignoring both of them to save a few quid on a potentially lifesaving device would be rather negligent.

 

[Fredstudio]

Were would the rcd be added if its an old fuse board?

 

[flameport]

RCD could be added somewhere along the existing cable, either next to the fusebox, or in some cases on the wall outside the bathroom (can also be used as an isolator there if required).

An example would be one of these: http://www.toolstation.com/shop/p94629 fitted into one of these: http://www.toolstation.com/shop/p30350
connected to the existing fuse in the fuseboard.
However this is only possible if the existing cable and fuse is suitable for a new shower.

Other options include a totally separate consumer unit for the shower only, such as http://www.toolstation.com/shop/p29044
Or the entire fusebox could be replaced.

 

[Fredstudio]

Can I also ask what size shower can be feed of 6mm cable an what needs 10mm? I am just trying to learn more about it, but I will an electrician to look at this job.

 

[JohnW2]

Were would the rcd be added if its an old fuse board?

Most commonly, close to the fuse board - but it can be inserted into the cable anywhere between the CU and the shower.

Kind Regards, John

 

[Fredstudio]

Thanks have you by any chance got a link to a picture of how a rcd connected some were on the shower cable would look like?

 

[Taylortwocities]

It looks like this
http://www.tlc-direct.co.uk/Products/WYWRS80slash2.html

But don't worry about the details as

I will an electrician to look at this job.

He/she can tell you if the cable size, CPD and the existing fuseboard are up to the job as well as advising you where the RCD can be located.