RCD addon board from screwfix - can someone confirm what it does....

None - it's a 3 phase RCD

these are easy

It's a 3 phase RCD for industrial/commercial applications. It has no value in a house installation. Even if you use electrical heating in a large TT earthed house and hence have 3 phase, you are unlikely to want a whole house

To protect multiple circuits with RCD protection without putting an RCD on critial circuits, such as lighting and fridges, you have the following options:

1. Replace the MCBs for the specific circuits with single width RCBOs. (Best, if available)
2. Replace the consumer unit with a split load unit (Poor discrimination, but cheap)
3. Use a standalone RCD unit for each specific circuit (Expensive, takes space)

Christian.

Thanks for advice. I don't really want to replace consumer unit with split one as that involves paying someone to fit it :( Also there are only really

Must confess I've not come across a RCBO before? Is it a RCD / circuit breaker combo type thing, and do you get them single fitting size for consumer units?

Even better, anyone got links for them in 32 and 16 amps?

It is and you do. However, whether they are available for your specific consumer unit can't be certain.

Christian.

They're also generally 2 units wide - at least all of the ones that I have come across have been. Do you know if it is possible to get single width ones?

-- Richard Sampson

email me at richard at olifant d-ot co do-t uk

here

It is. However, whether they are available for your specific consumer unit can't be certain.

Example:

At about £40 that doesn't seem too far out of line with the double width ones I've seen in screwfix.

Hager CUs any good? Is it generally better to go for a plastic or a metal CU?

(this CU replacement project is beginning to gain momemtum, ahead of implementation of the new part P regs...)

-- Richard Sampson

email me at richard at olifant d-ot co do-t uk

actually, reading further, the difference between these single module RCBOs and the MK double module RCBOs is that the MK ones are double pole rather than Hager's single pole.

This might have a bearing on the choice of make... take it they're not compatible between makes/CUs?

-- Richard Sampson

email me at richard at olifant d-ot co do-t uk

Although Hager also make a double pole variety in a single module format, can't remember the cat. no. off the top of my head. The problem with trying to find everything on tlc and such like places is that they distribute common items whereas using wholesalers like what I do you generally come across most things when wandering about the stores or thumbing through vast libraries of catalogues!

SJW A.C.S. Ltd.