Up front Rcd question

[Dirk boddington]

After talking to someone who's Rcd failed them recently during a regular test it got me thinking.

I have a TT system and regularly test my rcd however if it failed to operate during a phase to earth fault then there is no backup.

I considered upgrading the consumer unit and adding rcbos but that's well beyond my budget right now. (they may fit in mine now but it will be very tight)

My second thought was adding a rcd in line with my existing consumer unit to act as a backup. All of my circuits are fed from this single rcd at present as its not a split load unit.

I've spoke to several electricians about it and I've had varying answers so thought I would ask a wider audience.

Can this be done with 2 30ma rcd or would this create nuisance tripping or would one have to be a 100ma?

 

[swift_2]

Put a 30mA 80/100 amp rcd between the tails from the meter to the fuseboard. This way if one fails the other one hopefully will trip. There should not be any discrimination between the two. Small housing with the rcd on, mount it between the meter and fuseboard and sleep well.

 

[ackbarthestar]

calibrated test equipment but were really going off track here...

Why wouldnt you have two in series?

Well there are examples where two series connected 30mA RCDs are used. One might be marinas and the other might be Caravan sites.