RCDs and nuisance tripping

[Gardner]

Do RCDs nuisance trip without an earth fault or is a tripping RCD always the sign of an earth fault?

 

[malcolmsanford]

Not always it could also be that there is a neutral earth reversed somewhere in the circuit if it's a new circuit.

If it is on a board change it could be either a borrowed neutral or on a split board you have connected the wrong neutral in the wrong bar.

If it is a fault on a circuit then it could be an appliance, or a trapped cable or indeed as you say a fault, testing will sort that out

 

[Gardner]

Not always it could also be that there is a neutral earth reversed somewhere in the circuit if it's a new circuit.

If it is on a board change it could be either a borrowed neutral or on a split board you have connected the wrong neutral in the wrong bar.

If it is a fault on a circuit then it could be an appliance, or a trapped cable or indeed as you say a fault, testing will sort that out

But if the RCD is wired correctly (no faults and high insulation readings), they do not nuisance trip, correct? Tripping always equals earth fault?

Just double checking.

 

[malcolmsanford]

Is this a domestic installation.

Have you ramped tested the RCD?

 

[Gardner]

Is this a domestic installation.

Have you ramped tested the RCD?

Yes, domestic installation with twin and earth. No ramp test.

But its safe to assume, that if the RCD is randomly tripping it is indeed sensing an imbalance?

 

[malcolmsanford]

An RCD will only trip when there is an inbalance you are trying to find it.

Sometimes there can be circuit protective currents in a system. Not likely in a domestic installation unless there are a lot of switch mode equipment such as TV, Comp games, computers etc.

What have you tested to see what is tripping the RCD. Have you done the basic ie unplug everything

 

[davesparks]

RCD trip = current imbalance

 

[Gardner]

Ok, what threw me off was the occasional, random tripping. So this is indeed a current imbalance that needs to be traced.

Is it normal for appliances to trip them?

 

[Pete999]

Ok, what threw me off was the occasional, random tripping. So this is indeed a current imbalance that needs to be traced.

Is it normal for appliances to trip them?

Only if the appliance has a fault present

 

[DPG]

As per post #4, have you tested the RCD? Daz

 

[Marvo]

Ok, what threw me off was the occasional, random tripping. So this is indeed a current imbalance that needs to be traced.

Is it normal for appliances to trip them?

No, not normal but also not necessarily a fault, could be bad circuit design. The earth (CPC) is functional as well as protective.

 

[Deleted member 72666]

But if the RCD is wired correctly (no faults and high insulation readings), they do not nuisance trip, correct? Tripping always equals earth fault?

Just double checking.

I take it you mean low insulation reading.

 

[telectrix]

could be gremlins. nasty little critters.

 

[Guest77]

Do RCDs nuisance trip without an earth fault or is a tripping RCD always the sign of an earth fault?

Are you an Electrician? do you understand how an RCD works? if not and I am being kind- should you be working on circuitry? no offence.

 

[davesparks]

I take it you mean low insulation reading.

No, he means high. If it was low then tripping would be expected. He is asking if a circuit with a high IR etc would suffer nuisance tripping