Insulation Testing

[spanner51]

Further to my earlier topic, I have just purchased a Megger insulation tester, brand new, from ebay. It was a great bargain. However the crocodile clips are just a little too small to bridge the L and N pins on the plug when testing. I’m not sure weather to do 2 tests, 1 on the L and earth, and 1 on the N and earth. I dont want to blow any sensitive p.c.b’s.

Any thoughts on the subject?

[maltheviking]

Re: Insulation Testing

spanner51 wrote:Further to my earlier topic, I have just purchased a Megger insulation tester, brand new, from ebay. It was a great bargain. However the crocodile clips are just a little too small to bridge the L and N pins on the plug when testing. I’m not sure weather to do 2 tests, 1 on the L and earth, and 1 on the N and earth. I dont want to blow any sensitive p.c.b’s.

Any thoughts on the subject?

Graham 😯 Are you sure you know how to use these instuments correctly and safely ? 😕

[spanner51]

Re: Insulation Testing

Yes
Unlike the green light pass, red light fail brigade, I use mine for actual readings, and fault finding, i.e. motors, heaters etc, down to earth. When someone else’s method’s are different to other’s, it doesnt make them wrong.

[maltheviking]

Re: Insulation Testing

spanner51 wrote:Yes
Unlike the green light pass, red light fail brigade, I use mine for actual readings, and fault finding, i.e. motors, heaters etc, down to earth. When someone else’s method’s are different to other’s, it doesnt make them wrong.

Don’t get me wrong Spanner but the question you were asking does give a little doubt, I am sure that you do know what you are doing, in answer to your question I would not do an insulation test between L and N and should only be between Earth and L/N if your crock clips are too short then clip it to a screwdriver and use it across both pins 😉

[Alan1476]

Re: Insulation Testing

Just A quick Note: 😮
Be extra carefull when testing from the plug for an eatrh fault in todays modern machines as the electronics are so sensitive you could be doing more dammage than the worth of it. 😆 😆

[maltheviking]

Re: Insulation Testing

Alan1476 wrote:Just A quick Note: 😮
Be extra carefull when testing from the plug for an eatrh fault in todays modern machines as the electronics are so sensitive you could be doing more dammage than the worth of it. 😆 😆

I must have been lucky I can honestly say that I have never damaged a pcb. with a insulation test :rolls: I am probably teaching my granny to suck eggs here, but I make sure that when I do a test, I test all the machine, this cannot be done from the plug on some appliances that have a heater relay(only in circuit when energised) 🙂

[spanner51]

Re: Insulation Testing

I have always tested between E and L/N , that was my query. I always test every appliance after a repair, to make certain it is safe for the customer, and to cover myself.

[squadman]

Re: Insulation Testing

The way we were taught to perform a insulation test was as follows:

1. Earth to Appliance Chassis

2. Earth to Live > 1.meg Ohm ( Some Say 2 meg ohm )

3. Contunity < 2 meg ohm, (problem when appliance has push or relay start)

I was talking to some engineers the other day and they perform the same tests with a couple using loop impeadance testers which also function as insulation testers.

I have never blown a pcb under any of these tests set at the 500v settings or heard of anyone causing damage. However it still surprises me that there are engineers who say they do not have a insulation tester as part of their kit and that they have never needed one !

Mm

[maltheviking]

Re: Insulation Testing

spanner51 wrote:I have always tested between E and L/N , that was my query. I always test every appliance after a repair, to make certain it is safe for the customer, and to cover myself.

What about testing the appliance BEFORE you repair it? for your safety,
risk assesment etc

[spanner51]

Re: Insulation Testing

Most service manuals I have seen, state that you should do an insulation test both before and after a repair, (which I always do) It also stops the customer accussing me of causing a failed test. I usually issue a test certificate, as well as the customary sticker, to make a good impression. And it does.

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