RCD Tripping - Why!?

[robjs]

About 6 months ago we had a new kitchen fitted and because it involved work to the electrics, a Wylex RCD box was fitted which was linked up to kitchen power (excuse the terminology, hope you get what I mean).

Apart from the occasional trip out which we put down to the iron, it's been fine. However, over the last 2 weeks it's been tripping out lots.

It all started over the same weekend as we had a power cut so we put it down to that but EDF have said all faults have been cleared but it's still tripping roughly every other day (just the kitchen RCD circuit, none of the other parts of the system in the older style box trip).

Things which baffle me:

It seems completely random.

It often trips out in the middle of the night (nothing is timed to come on which is linked to it)

Yesterday, all of the house lights flickered and then the RCD tripped out (this doesnt usually happen). At that point we had just switched on the tumble drier in the garage which isnt on the kitchen circuit. This is left unplugged over night.

I've started to unplug various items to see if it's an earth leak in an appliance - so far it isn't the kettle, toaster, radio. Other things always plugged in are the american style fridge freezer (6 months old), TV & broadband equipment, microwave, dishwasher and washing machine (also new).

Before I get an electician in is there anything I can do to work this out? I'm still suspicious of the extenal factor but EDF say all faults are now clear so I need to be confident it's their fault if I go back to them.

Sorry for the long post, I'm just trying to give all the detail!

Thanks

 

[ericmark]

There are many things which can cause an RCD to trip. Spikes on the power being one. So a bad connection can cause spikes and can cause it to trip.

However if one is looking for faulty appliances then buying a plug in 10ma trip is one way to test. Note 10ma not 30ma.

One item listed is something to consider. Any frost free freezer has a timer which switches on a de-frost heater. This could happen in middle of the night.

One problem where multi items are on same circuit is that with a neutral earth fault it will only trip when the current drawn exceeds a limit so can give wrong impression as to which items are faulty.

As an electrician I would unplug all items and test circuit. Then I would test all items with a PAT tester to monitor any leakage. 9 times out of 10 that will high light problem. But washing machines, frost free freezers, etc have parts that switch on after some time so unless I waited until whole cycle was completed then I can still miss a fault.

There are RCD's with warning lights to tell you when the leakage is near the trip limit. However can't remember who makes them. Was in trade mag but forgot to make notes. Maybe some one else can help.

 

[ban-all-sheds]

A modern F/F will come to no harm if left unplugged overnight, as long as you stop the midnight fridge raids. As long as the doors aren't opened stuff will stay cold. You could always turn it to the coldest settings for a few hours before unplugging if you want extra peace of mind.

 

[robjs]

As an electrician I would unplug all items and test circuit.

Thanks for the replies both. When you say (above) do you mean "test" as in use the test functionality build into the RCD box, or some other method (I don't have any equipment)?

Thanks

 

[TicklyT]

Another characteristic of fridges is to drain the melt water from the defrost cycle into a tray on the top of the motor, where the heat generated by the normal working cycle evaporates it. Sometimes that tray overflows onto the motor.

 

[robjs]

Interesting the focus of replies is the fridge freezer - would you expect a 6 month old appliance to cause these issues?

Have been unplugging the microwave when not in use since last trip and haven't had one since. Can't be sure it's that but it's looking likely. Would that mean the microwave should just be scrapped?