Megger testing [pat testing]

[dave friday]

The only thing on and off between 23hours and 11am is the water heater.

[R0B]

John.(g.h.o.s.t) Us mods don't have access to the swear filter.Admin only.

[dave friday]

The RCB wouldn't latch this am (with the mains off) ( it tripped earlier on) so I replaced it ,ok so far!
Another question;what appliances shouldn't be Megger tested?
Ta.

[ghost123uk]

Depends on how you define a Megga tester. Most modern "safety testers" are referred to as "PAT" testers and have built in pre-programmed settings that you choose based on what you are testing. This can be like:-

A 2 wire device (no "earth" = double insulated) with no delicate parts inside, such as a table lamp or simple hair-dryer
or
A 2 wire device (no "earth" = double insulated) with delicate parts inside, such as a modern Hi-Fi or a "smart" hair-dryer etc
or
A 3 wire device (earthed) with no delicate parts inside, such as a simple tumble dryer (mechanical timer) or a simple electric drill (no speed control) etc
or
A 3 wire device (earthed) with delicate parts inside, such as a "fancy" tumble dryer (electronic timer) or a "fancy" electric drill (with speed control) etc

So it gets complicated what with so many seemingly simple devices having delicate electronic circuits inside, as per the examples above of a hair dryer, which these days might have fancy electronic temperature control circuits inside, same with drills and tumble dryers etc etc etc.

Part of some tests include sending a high voltage around the device to test "insulation breakdown" but if the device has any "electronics" inside, this will damage it. Personally I would avoid high voltage tests, you never know whether the thing you are testing might have some sort of electronic circuit, even if it's just a simple component (like a Varistor) to prevent it radiating interference. I reckon modern PAT testers have different methods of doing those tests, though as I say, it was a good few years ago since I last used one (and went on the course).

[dave friday]

Ghost ,thanks for a very full reply! The last thing I Megger tested was in the mid 70ties!
I've had a look at the RCB,the contact I've looked at is very burnt n blackened and a small Spring had come loose!
We will see if the new RCB trips over the next week or so!

[dave friday]

The new RCB tripped around 17.00!! Not much on at that time just fridges n lights,back to the drawing board!!well test gear.

[dave friday]

Update..the RCB tripped and couldn't be reset! I checked the water boiler with test meter 7.5k ohms live to earth,later 12meg ohms..checked with a Megger..dead short!!
Today new boiler fitted.
Just waiting for one of the cats to pi$$ on a main socket !!