showers and rcd

[peter t]

I have 2 similar questions:

1. I have to replace an electric instant shower due to a faulty solenoid and the instructions for the new shower state that I SHOULD have an RCD as part of the consumer unit or separate (between the consumer unit and pull cord isolating switch). In my current set up I do not have an RCD. The consumer unit is an old Crabtree type (trip switch but not with RCD) and i am told by a local supplier that they no longer make replacement switches that encorporate RCD. Since the manufacturers are only saying i SHOULD have an RCD, can anyone advise me of the dangers and necessity if I dont. I have used electric showers for many years without one.

1. A family member has a similar set up (not Crabtree but with a replacment MCB installed in an old unit). Again the shower is not protected by an RCD. They may be selling the house in the new year. Will this omission hamper/ prevent the sale. Should they get an RCD installed. I am aware you can puchase shower upgrade kits. If the work is carried out after 1.1.05 by a qualified electrician will they need this new P form and is there a cost implication?

Many thanks. pete t

[peter t]

I have just read a number of previous topics on this matter and it clearly is not as straightforward as I first thought. I think i need to obtain more information about the MCB and distances from consumer unit to shower etc before a decision can be made. pete t

[Christian McArdle]

Personally, I would definitely install one, even if not required. However, if the manufacturer of the device specifies the device, it become a requirement, so you must install one.

It is easy to insert an additional RCD. Somewhere between the consumer unit and the shower (but not accessible in the bathroom), you just need an RCD, which will consist of a simple 2 way enclosure and a 63A 30mA RCD, such as the following.

[peter t]

consumer unit

Christian, Thanks for the advice and links pete t

[Tim (Remove NOSPAM.]

Stop right there. You need an RCD with an Electric shower. End of story.

If the shower frame is metal this must be earth bonded, and so must the copper pipe (if its copper) and any other copper pipes in the shower room. (Well whole house really, but here at least!)

Tim..

[Stefek Zaba]

I don't see that following strictly from the current Regs. Personally, I'm much happier with the idea that the combination of nakedness, water, earth-referenced bonding, and 240VAC is supervised by an RCD; but AFAIK the letter of the Regs doesn't (p'raps surprisingly) require an RCD for showers. The disconnect-time/touch-voltage with a 40A breaker in the event of a L-to-E are easiest to meet with an RCD, but for a short cable run calculations may often pronounce the "normal" MCB to be protection enough. Not to say that an RCD isn't a good idea, though...

[Dorothy Bradbury]

There is an MK 45A RCBO on Ebay UK - down at £28, new in box I believe.

If the shower isn't on an RCD, might be worth checking the cable is of the correct size at the CU - just in case someone cut any corners.

[Andrew Gabriel]

Well, that's simply not true, unless your eath fault loop impedance is such that you need one to meet disconnect times on earth short. You might choose to have one for piece of mind, or because you can't test your earth fault loop impedance.

[Dave Plowman (News)]

Why? Sorry to be brutal, but you don't *need* an RCD on any appliance which is also connected to or holds water - immersion, washing machine, dishwasher, kettle etc.

Remember, water itself is a very poor conductor of electricity.