Induction hob tripping RCD

[Andy Wade]

Yep, you've cleared up that possible misunderstanding.

I don't think anyone has asked what sort of meter you're using. At the risk of raising a cry of "grandmother, eggs, sucking," are you sure that the reading was really 2.9 A and not perhaps 2.9 mA? I'm thinking that some of the Fluke DMMs just display a number on current ranges, and whether it means amps, milliamps or microamps depends on which socket you've plugged the red test lead into.

Even 2.9 mA's a bit on the high side, but much more feasible than having nearly 3 A flowing in the earth wire.

What happens if you use a 12V 50W bulb in place of the meter? At 2.9 A it should light up nicely.

Perhaps it's too late and we'll never know...

[Michael Chare]

Yes, in this case the appliance was correctly earthed. The problem for the repair man was that the bottom plate formed part of the earth circuit. A better design would have ensured that the internal compnents were earthed even with the bottom plate removed. (Atleast that is how it appears, I have not studied it in detail)

[Peter Parry]

2.9mA is about right for a noise filter (usually 2-3.5mA)

[Andrew Gabriel]

For Class I IT appliances (ie. computer), max permitted is 0.75 mA. They are normally about half this though. I think this limit applies to most types of Class I appliances which plug in to a standard socket outlet, but they are all defined in different EN documents, so it would take some research (and considerable expense) to get a full list of figures. Wired-in appliances are probably allowed higher leakage.