Right – I need to test the impedance between the surface of a stainless steel, portable table and steel plates placed under the wheels. The wheels are anti-static. To satisfy the test criterion,
the measured impedance must be >50kOhms and <2mOhms. The test voltage applied across the two points must be at least 500V. Two questions:

1 – what test equipment do I need? (a multimeter will only provide a few VOlts.)

2 – How do I carry out the test for most accurate results?

Thanks for any suggestions.

You’ll want an insulation tester. A Megger or maybe a PAT tester.

You can hire calibrated ESD kit which will apply a high voltage for you and measure what gets through.

http://www.livingston.co.uk/p_megger/electrical-industrial-test/electrical-installation-test/megger-mit510/

Megger is the way to go.

Unless you need to do this regularly the price of the kit will shock you. If that is the case maybe look for a contractor that can test give a record of compliance

Good point from pbc. If it is a one off then get someone in. They’ll have the kit and know what they are doing.

If it is a one off then get someone in. They’ll have the kit and know what they are doing.

The latter being a very important point if you’re putting 500V across parts with lots of surface area it’s easy to make contact with. I’d be far more concerned about safety as a first priority. If you are considering doing it yourself, do make sure to do a proper risk assessment and take appropriate safety measures.

The latter being a very important point if you’re putting 500V across parts with lots of surface area it’s easy to make contact with

The test kit will be current limited, so it’s not like you’re wiring the thing up to 415v supply…..

you only ever make a mistake like that with a megger once! (also you don’t die btw but you will wonder wtf happened!!!)

The test kit will be current limited, so it’s not like you’re wiring the thing up to 415v supply…..

Yes – but his minimum impedance is 50kOhms, which gives a required current of 10mA. Not huge, but plenty enough to be a problem if you don’t take precautions.

Oh, and one more option is to speak the wheel manufacturers. If the wheels are designed for this very application then they might have some figures. It’s not a substitute for testing but it depends what your use is.

[video]http://www.youtube.com/watch?v=RtlYi1yLTVQ&feature=player_embedded[/video]

😉

I also assume you mean >50KOhm <2MOhm btw!

What you want is indeed a Megger tester, assuming the rest of the table is steel, and hence highly conductive, you could probably just get one of the wheels tested. You might have an issue that you need to partially earth the table to get below the 2MEG requirement?? (low enough to prevent static charge building up, but high enough to prevent significant current flow in the case of an HV fault / short etc)

I also assume you mean >50KOhm <2MOhm btw!

Unlikely.