RCD and ring mains

[Paul999]

The RCD in my consumer unit has been tripping out a lot recently when appliances are switched on in the house particularly during the evening when there is more load being drawn. I am thinking it is down to the RCD being overloaded rather than any earth leakage. The circuits which pass through the RCD inlclude both ring mains for the house as well as external radial circuits feeding external lighting and gates etc. and oddly one of the houses's lighting circuits. Other circuits such as the cooker and the reminaing lighting circuits do not pass throught the RCD. The rating of the RCD is 63A, which I believe is the lowest rating for a typical domestic consumer unit.

Is the solution to rewire the consumer unit so that the ring mains do not pass throught the RCD (after checking there are not outside spurs)?
OR
Should I be replacing the RCD with a 80A or 100A type?

 

[DESL]

I am thinking it is down to the RCD being overloaded rather than any earth leakage

Highly unlikely

RCD will function when there is an imbalance in the current flowing in the nuetral and live.

The 63A or 80A you refer to is the maximum load current rating for the RCD.

Changing from a 63 to 80A will not stop the tripping.

Is the solution to rewire the consumer unit so that the ring mains do not pass throught the RCD (after checking there are not outside spurs)?

No - this could mask a potentially dangerous fault that could lead to an electric shock!

The fault could be damp/moisture in one of the outside circuits

An insulation test of all the circuits on the RCD side of the CU will identify which circuit is causing tripping.

Unless it's a combination of several 'leaky' appliances causing a commulative leakage current sufficient to trip RCD

 

[baz1968]

Residual Current Devices protect against earth leakage and not overloads. Earth leakage faults are tricky to track down. You may have an exterior circuit that is prone to rain or damp. If it trips when a particular appliance is switched on or when an appliance is plugged into a particular socket then you may have either a faulty appliance or a fault with the socket circuit. If you find that the fault seems to move around or when a combination of appliances are used then i would expect that the RCD itself is faulty. The maximum earth leakage current for an RCD protecting socket outlets is 30 milliamps and this should not be exceeded. Some RCD testers have a "ramp" function that allows testing of the tripping current and will determine if the RCD is at fault. A competent electrician will be able to test this for you. You should not attempt to replace this yourself.

 

[Lectrician]

Residual Current Devices protect against earth leakage and not overloads. Earth leakage faults are tricky to track down. You may have an exterior circuit that is prone to rain or damp. If it trips when a particular appliance is switched on or when an appliance is plugged into a particular socket then you may have either a faulty appliance or a fault with the socket circuit. If you find that the fault seems to move around or when a combination of appliances are used then i would expect that the RCD itself is faulty. The maximum earth leakage current for an RCD protecting socket outlets is 30 milliamps and this should not be exceeded. Some RCD testers have a "ramp" function that allows testing of the tripping current and will determine if the RCD is at fault. A competent electrician will be able to test this for you. You should not attempt to replace this yourself.

NO!

This fault is very indictive of a Neutral to Earth fault on any one of the RCD protected circuits. The more load you draw, the quicker it will trip as some of the return neutral current is able to flow through the higher impedance N to E fault as a secondary returm, causing an out of balance.

I would be happy to place money on this being the problem

 

[securespark]

And I would be happy to second Lec's opinion.

 

[baz1968]

And I'm entitled to my opinion Let's hope the op lets us know what the problem was.

 

[ebee]

It`s unusual for RCDs to be oversensitive in fact it`s more likely that they fail

 

[ColJack]

it's not a case of being over sensitive, it's more of a case of cumulative leakage..

the fact that it happens in the evenings will probably be more to do with things like the computer being on, the kettle in more use, the cooker being used, the washing machine on, the boiler firing more often when it's cooler in the evenings, more tv's on etc etc...

all create ( or are capable of creating ) some earth leakage