Rcd problems

[sidekick]

Following the addition of a socket to a ring circuit I have just carried out the RCD trip test with a Fluke tester.
The RCD would not trip on x 1 or x 5. Then tried the test button on the RCD and it would still not trip even with all the circuits turned off.
On closer inspection found that the line conductor to the RCD was connected at the base along with the bus bar (bypassing RCD) also found a link had been added between the two neutral bars.
After speaking to the customer it transpires that on fitting of a new kitchen the electrician also convinced them a new consumer unit was required (no reason not to believe that) However, after fitting the split load unit the RCD constantly tripped on all socket circuits ( x 4 ). Customer was advised too much leakage and the RCD was bridged to allow power to all circuits.

What is the best way to go about putting this right to give RCD protection.

 

[Octopus]

With 2 circuits working and 4 tripping the RCD's are you sure that the neutrals were all connected to the correct bars?

 

[topquark]

Almost sounds as if you don't have both ends of the rings correctly identified. Is it possible that RFC1 out and RFC2 in are paired and RFC1 in and RFC2 out are paired, not necessarily by you

Edit:
You may only be looking for one fault if that's the case.

 

[sidekick]

Test the RCD in isolation (with no other circuits attached) and ensure the test button is working correctly (the RCD may be faulty).

Thanks Topquark. Done that and even replaced with new RCD i had in hand and same results.

 

[sidekick]

Maybe the rings are interconnected, go back to basics, ring continuity checks and IR testing, assuming no loads, these 2 tests will give you all you need to know.

Thanks IQ Electrical. Thats my plan.

 

[sidekick]

With 2 circuits working and 4 tripping the RCD's are you sure that the neutrals were all connected to the correct bars?

Thanks Murdoch. Disconnected all Neutrals and ensured correctly re-connected as far as the line conductors in the MCB's are paired with them.

 

[sidekick]

Almost sounds as if you don't have both ends of the rings correctly identified. Is it possible that RFC1 out and RFC2 in are paired and RFC1 in and RFC2 out are paired, not necessarily by you

Edit:
You may only be looking for one fault if that's the case.

My thoughts exactly. As I now intend to do the basic ring and insulation tests etc I will find if thats the case.

Will let you all know what the result was. Cheers

 

[sidekick]

Hi all, Update on this thread is that following ring tests on these circuits I found the following :-

On three of the four circuits tested all was ok and good insulation test results.
However, on the fourth circuit, three wires were present.
The three line conductors into the MCB were two on a ring and the third on a radial. The radial was only 2.5 t/e on the 32 MCB and had 4 2g sockets and 1 3g socket on it. Corrective action on this part not yet done.
The other two which were on the ring failed insulation test on cpc to neutral so when RCD wired correctly fault was neutral to earth bar so all circuits tripped RCD. I split the offending ring at various points to narrow down the problem to two seperate faults. First was a damaged cable under the downstairs kitchen floor trapped under a replaced floorboard. I replaced that length of cable. The second fault was between a junction box under the kitchen floor and two sockets hidden with newly installed kitchen units. Unable to get to the one of the two sockets i ran a new cablefrom under floor to next used socket and by passed the two hidden which were unusable anyway. could have been fault in socket or screw from kitchen unit fixings in cable who knows but problem solved. RCD then wired correctly in consumer unit and all works fine. Testing complete and satisfactory. Now to correct the radial, no spare way to run from a 16A and no obvious way to access cables other than at consumer unit as yet.

 

[Richard Burns]

Thanks for the update always nice to know how things turn out. Well done on identification and rectification, hope someone does not try to reconnect the bypassed sockets! Good luck with sorting the radial, sound like it is a bit of a practical problem there.

 

[oxocube]

^^^^^^ I agree, its always good to get feed back for everybodys education.

 

[mogga]

everydays a school day

 

[sidekick]

Thanks for the update always nice to know how things turn out. Well done on identification and rectification, hope someone does not try to reconnect the bypassed sockets! Good luck with sorting the radial, sound like it is a bit of a practical problem there.

Cheers. Cut both the cables to the hidden socket under the floor very close to the boards so no chance of access to socket or cables unless kitchen comes out.