Consumer unit

[PLC54]

Should a RCD be fitted to a TNCS earthing system? as i have fitted a new split load consumer unit. When i connected the sockets ring main to RCD side as soon as power is turned on RCD and Mcb Trip.I then transfered the sockets ring to non RCD side and it worked ok,could you advise on possible faults.

 

[davelx]

Does the RCD trip even if there is nothing at all plugged into the ring? If so, you probably have a short somewhere on the ring. The fact that the MCB trips suggests this.

Did you do ring continuity, polarity and insulation tests before you connected up to the new CU?

Did you connect the neutral to the correct neutral block - there are two in a split load CU?

Does the RCD trip even if there is nothing at all plugged into the ring?

And can you post a photo of the new CU innards with the ring connected to the RCD side - you may have made a simple wiring error that we can spot.

 

[davy_owen_88]

Should a RCD be fitted to a TNCS earthing system?

Yes. 30mA protection for socket outlets and certain bathroom appliances.

as i have fitted a new split load consumer unit.

Did you inform your BCO so that they could inspect and test your installation? If the answer is no, then pack your bags, you've just won a one way ticket to hell!

When i connected the sockets ring main to RCD side as soon as power is turned on RCD and Mcb Trip.I then transfered the sockets ring to non RCD side and it worked ok,could you advise on possible faults.

MCB's trip during overload/short circuit conditions.
RCD's trip during earth fault conditions.

Could any of the conductors have been touching in the CU the first time?

Since both tripped I would have assumed you had an earth fault that was taking them both out but since you don't get any tripping when on the non-RCD side (the MCB should still trip regardless of the RCD) I'm going to bet 10p that it was just sloppy wiring and bad luck that there was some contact between conductors and has gone away because you have moved the cables. This does not make it safe though, any snags in the insulation could become a problem later on and I suggest you get a sparky in to have a look ASAP.

Davy

 

[PLC54]

Thanks the information gents. PS I'm sure it was someone else that fitted the consumer unit !!!!!!!!!

PLC 54

 

[davy_owen_88]

This isn't a joke mate. You have broken the law by not informing the BCO, you haven't complied with BS7671 and you have left your installation in a dangerous state yet you don't seem bothered.

What do you intend to do about the tripping problem? Socket circuits must be RCD protected so leaving it alone is not an option.

 

[PLC54]

I can assure you that i am bothered and have taken your advice from earlier reply and got a qualified electrician to look at it tomorrow

Thanks PLC 54