Fused spur from ring RCD protected?

[pcboffinuk]

Me again

Can anyone confirm the following - I can't find anything in the OSG and while I think I know the answer I always like to gain confirmation...

Sorting out my mother's kitchen ring, I've discovered that there is a spur running from a single socket behind the washing machine, feeding freezer, two double sockets, and via plugs all the outside lighting, water fountain, etc.

I don't need to be told that this is 'a bad thing(TM)' and I'm currently planning to make it a fused spur, at least initially, as its easier than pulling the entire floor up.

When the CU is replaced, the kitchen ring will be RCD protected - my question: is a fused spur connected to an RCD protected ring, also fully protected by the RCD? If not, is it better practise to install a rcd FCU for the spur? If so is there any problem with diversity if that is 30ma, and so is the main RCD for the ring...?

Gavin

 

[Adam_151]

If the ring is RCD protected, anything connected to it via FCUs etc, will also be RCD protected so no need for RCD FCU, however you may want to consider using one to afford RCD protection to the load in the mean time while you get round to swapping out the CU.

I'm guessing you meant to type discrimination instead of diversity? The 30ma rcds will NOT discriminate with each other, a fault downstream of them both might trip either, or even both!

 

[pcboffinuk]

Thanks Adam,

That confirms what I thought - and yes I did mean to type discrimination

I'm hoping to swap the CU in the next week (already have the unit ready) so it will shortly be sorted.

Having seen the mess the fitters made of it though I'm expecting to uncover horrors for years to come

Cheers

Gavin

 

[securespark]

The only time to worry if a 30mA RCD will still be effective is where the EFL is higher than 1666 Ohms..... I have seen it, but it's rare!!