Equipment for detecting earth leakage in appliances

I'm doing 2330 at present and finding this forum a very useful teaching tool by pretending questions asked are the ones a customer would phone up asking an electricial and seeing if I can answer them successfully myself before all the experts jump in give advice.

I have noticed over the last few months that there are loads of RCD nusiance tripping questions along the lines what is causing it. Usually it is a leaky appliance. I myself have had two leaky appliances 1st a cord for a baby sterislier machine (for doing bottles before someone thinks I'm stopping future RJB generations!) and the 2nd the classic fridge freezer problems. Both was detected by my good self, thanks to this forum, by isolating all RCD protected circuits before introducing the circuits until the RCD tripped again using process of elimination technique.

Anyway my question is: (at last) Is there any equipment that simply indicates if current is leaking to earth in an appliance which woud cause RCD to trip. When I say simple I mean not the £800+ PAT testing that goes on in my office periodically.

The reason this would be useful I believe would be to quickly indicate to a customer that their appliance is causing the problem. I was thinking along the simplicity of a Martindale EZ socket tester. (plug and go).

Is there such a thing or am I barking up the wrong tree? (or just barking )

If there isn't watch out Dragon's Den!!

Insulation tester should do it.

L-E & N-E but not L-N as might fry electronics

DESL

On 500V as per normal domestic testing?


Also asking a L-N fault would not trip RCD would it as no current unbalance at RCD, Would that cause MCB / fuse to trip instead?

250V should do it if there is a fault

You're looking for a fault on an appliance not testing the integrity of a fixed wiring installation.

You'll have an IR tester in tool kit so it's just a convinient method of testing

I think the clue is in the question, Earth Leakage, the current LEAKING to EARTH usually down the EARTH, Green and Yellow wire. You could measure that with any multimeter set to AC milliamps in series with the earth connection to the appliance.

or a clamp meter if you can get at the cores individually and get it round the P+N.

I presume there must be some available with a smaller clamp than the usual 50mm size (how often does anyone need that?)

Ammeter on the CPC isn't reliable for appliances with parallel paths (like immersions and boilers)

I'm guessing that he was talking portable equipment, not fixed...
a plug and go solution..

If its a a simple resistive leakage... like current tracking across a kettle element (if you ever saw one open btw you'll see its very similar constrcution to MI cable), then an insulation tester will do.

If things are a bit more complex, and say for example the element isn't in circuit when its unplugged, or there are semiconductors which don't like IR testers (both of which apply to wahsing machines, dishwashers, etc) then you could dismantle it and test the element separately

If you don't want to tear stuff apart, or the leakage isn't just resistive (filtering circuits on IT kit, etc), then you'll want a residual clamp meter... a normal one isn't designed for measuring trivial currents!.

Another way round is to plug into an RCD socket, and do a ramp test with appliance, and without and the difference should be the leakage, and do it with all the appliances plugged in to see how much 'headroom' you have

The sense coil taken from dud RCD and a meter might work if the phase and neutral of a test lead were threaded through the coil and the voltage / current from the coil measured.

Would need to be calibrated but in theory it should be reasonably accurate. I dont have a dud RCD to get a coil from.