Faulty RCD?

[Adam1st]

Returned home late last night to a tripped RCD (Steeple 80A 30mA). Switched off all MCBs on the relevant busbar - still tripped. Even removed the busbar altogether - still tripped. Any advice gratefully received folks. Thanks.

 

[1john]

Neutral to earth fault. what was removing the bus bar going to acheive??

 

[sparkwright]

The fault cannot be found by simply disconnecting the live wires.

Firstly you should unplug (not just switch of at socket) all appliances and turn off all double pole switches (switched fused spurs etc).

Now switch on at the mains as normal. Hopefully the RCD will remain on.

Now plug in all appliances etc as normal.

As you do this, the RCD may trip, which will indicate a faulty appliance.

Don't forget outdoor stuff and central heating.

If you still cannot reset the RCD, there is probably a neutral to earth fault somewhere within the wiring.

 

[securespark]

Switch off all breakers and disconnect all neutral conductors attached to that RCD.

What happens when you switch on?

 

[Adam1st]

Many thanks for the three replies - they've helped my understanding considerably. I've now briefed a sparky from an informed position, and he's now sorted it. This is a very valuable forum, not just for professionals but also for those who know their limitations, but wish to engage in an informed way when they bring in appropriate professional experts. Cheers.

 

[maltaron]

Just for interest, what was the problem?

 

[Adam1st]

The sparky disconnected each neutral in the CU in turn, but the RCD tripped every time. It proved to be a live-earth fault, somewhere on the supply to an outbuilding/workshop. Circuit now disconnected, to be rewired in due course. Thank again for the helpful replies.