Changing A Rcd

[DanniW]

Hiya all, we have one of these in our house:

tinyurl dot com/p3vrouo

to complete his work, my electrician told me it needs to be replaced with an 80A 30mA version, which i could get off ebay.

I have looked on ebay and on the internet at large, and cannot find a 80A 30mA version with the same physical dimensions as the one above.

Does such a thing exist?

Thanks,

Danni

 

[ProDave]

That's an old obsolete style rcd.  You won't find one new so need to find a second hand one.

Why has your electrician lumped this on your? Surly he should be getting the parts he needs.  What exactly is he doing that needs this?

 

[DanniW]

Thanks for the reply ProDave

He is trying to keep the cost down for us.

He added a spur (I believe that is the correct terminolgy)

 

[Doc Hudson]

That looks like it is the main switch for the whole installation, in which case I would consider your electrician is wrong recommending you install a 30ma RCD to protect the whole property. If you are trying to keep costs down, just put a 30ma RCD Spur where he is doing his additional work and only test the new work. Otherwise he should do full tests on every circuit before putting in a 30ma RCD as a main switch, which may cost more in labour than a £25-£30 RCD spur. Why was this a 100ma RCD originally do you have overhead incoming power and your own earth rod?

Doc H.

 

[DanniW]

Thanks for the reply Doc, the additional RCD spur was an option, but it was thought that the replacement RCD was a better option. No idea why it was 100mA to begin with. No idea about incoming power or earthrod, sorry.

 

[Doc Hudson]

All new work should comply with current wiring regulations, as such a single 30ma RCD protecting the whole of the installation would not comply with regulation 314.1. So replacing your 100ma RCD is possibly not the best option if compliance with wiring regulations is the objective. There is no obligation to bring unaltered parts of any installation up to current regulations. Only new work must comply, so an RCD spur could actually be the easiest option both to source, fit and have some known quality, reliability and warranty of the product should it fail in an unreasonable timespan. I am not sure what warranty you would get off a secondhand e-bay purchase? It could be false economy for a device that is intended to reduce the risk of electric shock.

Doc H 

 

[DanniW]

Thanks, I will take your advice Doc.

 

[ProDave]

How much spare space is there in your existing consumer unit?

If you really want to do the job for the minimum, then I probably have somewhere a 30A/30mA double pole rcbo and the dual busbar for it that they used to fit in those old Wylex consumer units.

 

[DanniW]

Very kind of you ProDave, but I have no idea??

 

[Blue Duck]

Is it broken?

Is it installed in the fuse box or external?

Has it been tested?

Yeah its old but if it works within 200ms then its okay? 

 

[Andy™]

Is it broken?

Is it installed in the fuse box or external?

Has it been tested?

Yeah its old but if it works within 200ms then its okay? 

its 100mA.... needs to be 30mA

 

[batty]

Be careful installing RCD spurs had this recently when installing a towel rail in a bathroom. Same situation 100mA  RCD on mains problem is when testing Spur with test button it faults main RCD also and takes that out. Some of these old RCD's are very sensitive OK if its easily accessible but the one I had you needed steps to reset not good. 

 

[Bruspark]

The early 100mA ones did not have the time delay that was included in later ones to provide discrimination and immunity to the disconnect spikes from other RCD's being tripped or even tested.. 

 

[DanniW]

Thanks for all your help, I think it's a moot point anyway, I don't think 30mA 100A exist.