20 amp double pole switches

[WallaceP]

Hello,
Just wanted to share a fault I had today and was wondering if anyone else has come across it. So I wired a kitchen and the customer supplied the faceplates (I know...)
So after a lot more time explaining what they needed to buy and that a light switch would not work as an isolation switch for the oven(even tho they claimed that is how the electrician who wired their old house done it!)
Anyway, they called me back saying that the oven and dishwasher were tripping the RCD. I found that the 20a double pole gird switches must be switching the live before the neutral and because the new oven they bought have electronics in them this current must be wanted to return on the cpc and causing the RCD to trip.
The gridswitches were Varilight, which i would not have picked myself but they had already bought the other faceplates from this brand. I did not think they were a bad brand and I am fairly surprised with this fault and was wondering if it was more common than i realise.

 

[Dartlec]

Not one I've run into, though I don't install grid switches that often - and they usually don't get switched off very often. Is it repeatable - as in tripping every time the switch is turned on, and doesn't happen if the rcd is reset with switch on?

Varilight are a fairly decent brand - did they source them from a reputable supplier, or just buy them on ebay?

 

[PEG]

Hi,have you done all appropriate tests,to ensure this fault is the switch?

You would not want to obtain the best double pole switch in the world,only to find out there are other issues.

How are the grid switches configured,for these two machines?

...I bet it's easier to reset the RCD,than the clocks ...

 

[littlespark]

If they’re isolating switches, they should just be left on all the time.

 

[WallaceP]

All initial inspection was done at when the kitchen was wired. Today I rechecked polarity, earth loop, rcd ramp, rcd times, the end to end on the ring, resistance L-N (shorted at board) to each outlet.
The set up is kitchen ring with socket outlets 7 appliances on a 20amp switch each to a single socket. The fridge, freezer, cooker hood and wine chiller all work, but are very basic appliances, the oven, microwave and dishwasher are the ones causing the problem.
You would be able to switch on the grid switches maybe 1 in 3 times and not trip the RCD but if they are all on the RCD will reset. I have bypassed the neutral on the switch just now and it all works fine now, i could not get the rcd to trip when i turned the items on and off repeatedly

 

[telectrix]

as liitlespark says. they are for isolation , not on/off switches.

 

[WallaceP]

If they’re isolating switches, they should just be left on all the tim

Yes, but you should still be able to turn them on without causing a fault

 

[freddo]

Have you carried out insulation resistance testing on the appliances and wiring?