RCD instantly tripping??

[CRAIGNEWHAM]

Evening,
Just installed a new CU for a customer and one of the RCD's trips as soon as its switched on, even though the circuit beakers arent even on. Any suggestions about how to look for the fault?
Its 3 socket radial circuits that are causing the problem as it will stay on when I disconnect them?
Any help apprecaited
Craig

 

[topquark]

Assuming that there are no loads on the RFC, then check where the neutral has been put.

 

[Andy B]

Is it a split way board? Check that the neutral from the bottom of the main switch and the rcds are going into the correct neutral bars and that all the neutrals are connected into there correct bars.

 

[Mark_Burgess]

What make is it?

I had a similar problem with 2 Wylex RCBO's recently.

 

[CRAIGNEWHAM]

Checked them and they are in the correct neutral bars, and yes its a two way slpit board with 2 rcds

 

[DurhamSparky]

N-E Fault..!

 

[topquark]

Swap the RCD's and see if the problem moves with the RCD or stays with the RFC.

 

[Andy B]

Mark dont leave us hanging was the rcds faulty. what happened? I cant stand the suspense.

 

[topquark]

N-E Fault..!

One rather assumes that IR testing would have shown that up before energising the circuit

 

[DurhamSparky]

bang test...! i do it all the time!!

 

[CRAIGNEWHAM]

Its a volex

 

[DurhamSparky]

same make!!!

 

[Andy B]

not much bang with an rcd though.

 

[telectrix]

more of a clunk. it's deffo N/E fault or incorrect connections in the CU. check the manufacturers connected all the tails right and no loose terminations.

 

[CRAIGNEWHAM]

Its 3 radial socket circuits that I had to disconnect. Could it be that these are interconnected??

 

[telectrix]

Its 3 radial socket circuits that I had to disconnect. Could it be that these are interconnected??

get a tester on the radials. make sure there's no continuity between the 3 circuits, then IR test between them. could be a common neutral bridged across. are the 3 radials all on the same RCD?

 

[Andy B]

If they are all on the same rcd although its not correct it probably wont cause the rcd to trip. Can you not test it and see if they are interconnected.

 

[CRAIGNEWHAM]

I'll do that tomorrow

 

[CRAIGNEWHAM]

Yeah, there all on the same RCD

 

[telectrix]

have you tried connecting each radial in turn?

 

[CRAIGNEWHAM]

Ive tried connecting them seperately, and they trip still

 

[Hagar]

Got the same prob with a memera 2000 split box already has a ring main in working fine a cooker circuit working fine, i have just put two dedicated circuits in, one for a griddle one for a counter top boiler nothing else connected to either circuit, as soon as i turn the griddle on out goes the trip brand new cable 20amp switch etc checked cable with megger no faults if i move the mcb to the non protected side griddle works fine, boiler takes the rcd trip out even though its not fed through it any idea's ??


Hagar