RCD's in series

[SPARTYKUS]

Always a way La Poste!

 

[richy3333]

Always a way. If you can't do he job pro

 

[richy3333]

There's always a way. If you can't do the job properly don't do it. A good reputation is hard earned and easily lost.

Do you have any photos of this concrete bunker?

 

[mydigitalhome]

I have been doing some testing work on a Nursing Home (new client) which had two 30ma RCDs in series (1 x DB supplying 5 x DB's approx 40m appart) and while testing it was tripping at both RCDs 1 x on one and 5 times on the other really annoying as made testing awkward ! Not ideal.

Back to original scenario of outside supply I always put the outside supply on the non RCD side of the board supplied via a RCBO 100ma and 30ma at shed CU this gives full discrimination for the outside circuit. How do the rest of you do it?

 

[1shortcircuit]

I always put the outside supply on the non RCD side of the board supplied via a RCBO 100ma and 30ma at shed CU this gives full discrimination for the outside circuit.

Are you sure about that?

What are you doing when you're testing at x5 on RCD test?

You would need a time delayed RCD as I understand it from reading posts on the forum?

 

[mydigitalhome]

The RCD testing was not consistant sometime tripped only on one rcd other times took both out. Yes you are correct time delayed 100ma sorry took that for granted.

 

[Octopus]

Back to the OP, if the circuit serving the outbuilding is protected by a 30mA RCD, why bother with a 2nd RCD?

 

[Edd]

I've had discrimination with two 30ma RDC's where neither tripped on a fault, so i would not take the chance.

Im really intrested in this, anyone got a technical reason or idea why this could happen?

 

[SPARTYKUS]

Im really intrested in this, anyone got a technical reason or idea why this could happen?

Faulty RCDs? Cannot see any other reason theres no magic secret with them as far as Im aware. Needasparks what do you mean you had discrim. with two 30mA RCD's?

 

[Deleted member 26818]

The fault didn't produce a high enough fault current.