Standalone RCD question

[efiste2]

Can standalone RCD units still be bought. I want to install an RCD between the meter and the existing dis board, so the RCD device must be able to take the existing 16mm tails.

 

[Taylortwocities]

Yes they can be bought but you cannot do what you propose.

The RCD will be a single point of failure. So if the RCD trips then you lose all the power to the house.

 

[securespark]

He may just be wanting to give some temporary protection to some tails entering a metalclad board on a TT supply....or temp. protection for another reason?

 

[ericmark]

There are loads of RCD devices which can be box mounted but the self contained units like the picture

shows I have not seen for a long time. In fact the one shown is now banned as it is a voltage type.

We are required to:-
(iii) take account of danger that may arise from the failure of a single circuit such as a lighting circuit
(iv) reduce the possibility of unwanted tripping of RCDs due to excessive protective conductor currents produced by equipment in normal operation

Because of these requirements with the exception of caravans and the like we would not use a 30ma RCD to protect the whole installation under normal circumstances. However the use of 300ma S type (Delayed) is still common for fire protection and where a TT (earth rods) supply is used.

A garage or shower consumer unit can house these units without a problem. In domestic premises this would most likely come under Part P.

However now that so much needs 30ma protection in domestic premises it would be more normal to fit multi-30ma units rather than a larger RCD.

The 100ma RCD was the norm fitted with TT supplies but for fire we fit 300ma and for sockets over 32 amp we use 500ma so it may be hard to find the smaller 100ma units now but most likely the 300 and 500ma units would be OK for a TT system but would depend on the resistance measured on earth rod.

There are also combination unit like the Vigi where a MCB can take a unit to make it into a RCBO. As we go up in size there are add on units which can trip moulded circuit breakers but these larger units normally can be set as to what current they will operate at and what delay and as such must be fitted by a competent person.

 

[securespark]

Looks like a Wylex CO-ELCB to me. There's no earth connection to it, either.

The VO- ELCB's required an earth connection, without which they would not operate.

 

[RF Lighting]

This one has both earths in the 'out' terminal

 

[securespark]

You can rely on RF to come along at the right moment!

I've just come back from searching DIYnot for that image!!!

 

[RF Lighting]

You can rely on RF to come along at the right moment!

Not always at the right moment

 

[securespark]