RCD in garage

[Bright_Spark]

I have a split load CU in my garage, the RCD keeps tripping. tested the RCD and all is well, tested both breakers that it protects, again all is well. the install has been there for about 18 months or so and has been fine upto press. the rest of the install is ok, just the RCD. under test conditions it is doing exactly what it should...but every so often the blooming thing just trips out. when i reset it, its fine.....it mightbe ok for a couple of weeks there after, then it might only be ok for a day or so...

suggestions anyone? apart from putting a brand new one in !!!!!!

 

[JohnD]

Insulation test and Ramp RCD test.

Look for moisture in the fittings, including condensation. Especially outside lamps and PIRs, and water-containing appliances like washing machines, kettles.

Unplug all appliances.

Turn off the MCBs one at a time for a few days and see if that makes a difference. If not remove the Neutral as well as the Phase from one circuit at a time.

 

[Spark123]

I take it you are just protecting sockets? What is plugged in? Any outside lighting circuits from the socket circuit? Any damaged wiring? What are the insulation resistance test results? How did you test the RCD?

 

[Bright_Spark]

yep, just protecting a ring, which only has a fridge/freezer plugged in permenantly and the only other thing that gets plugged in now and again is the lawnmower!

i carnt understand it, done all the RCD test, 1x 5x etc, pulled the results out from when it was commissioned and ins res were all >999. checked the other day and L - N was slightly down, was around 700 but the rest were all infinate.

as for the garage i can see no physical defects with the building, there isnt any moisture around the CU or fixtures. its weather proof! lol

 

[JohnD]

Mice.

 

[THRIPSTER]

Spiders crawling between phase and CPC in socket outlets?

 

[securespark]

How did you test the RCD?

 

[Spark123]

Could quite easily be the fridge/freezer doing it, a little bit of earth leakage on the compressor and RCD trips.

 

[securespark]

You need to be sure to test the RCD in isolation. Have you done this?

 

[ricka]

maybe the start winding on the compressor leaking to earth or inside the freezer if it has a contol switch, water getting behind the gasket.