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I've just downloaded(read purchased) the draft revision of EN62353 and again 25A continuity testing has again raised its head!!
However they recommend the use of currents below 1A.

Malcolm.

I thought we were down to 200 mA!

25 Amps? In what context, I wonder.

(I wonder who's asking for that)

I suppose all the owners of the Metron QA90 or Rigel 277!!!!!!

Can't see the point of "standards" if they're being changed every year.

Neither am I a great fan of "adjusting" standards just to make them fit the status quo ante, as it were.

As far as I'm aware, volts are still volts, and amps are still amps ... etc., etc.; and leakage currents hazard limits (not to mention human physiology) remain as they always have been.

I have to say that I think large currents are good for earth bond testing. When I was just starting out, yes they did have electricity in those days, we have a high current earth bond tester (which made a lovely humming when in use from the transformer). There was more than one occasion when a multi core cable was being tested which passed initially then failed - we were good we kept the test running for the required length of time. The earth was partially broken and the high current over time blew the remaining cores like a fuse. This is what would happen in real life if there was a mains earth fault (assuming the supply fuse did not blow first).
This sort of cable would pass the instantaneous low current test of modern automated analyser.
Robert

The Rigel 288 has a fudge where it generates a spike of 25A then uses 200mA to measure the earth bonding. It's all to do with breaking down any contact resistance, apparently. It's not a real world test though, I can't think of any equipment that generates a spike to overcome contact resistance when you plug it in.

If I remember rightly, HEI-95 (and DB9801 Sup 1) went for 1 Amp. Yes; other historic documents are available (and more recent "guidance" has been silent about specific test current values)! And as Malcolm has indicated, various well-known bits of test kit (having been introduced at various epochs in the history of medical electrical safety) have tended to "do their own thing" (or perhaps simply followed what was de rigueur at the time).

Myself, I have usually thought that 10 Amps for five seconds was a good (and, dare I say, Real World) test current. Whilst I can see the merit in frying a few strands with 25 Amps, I can't really support that idea whilst also preaching that 10 Amp fuses be fitted to the ubiquitous IEC mains cables that are also rated at 10 Amps!

But rather than lay it all out again ... anyone who's still interested in this stuff could do worse than re-visit some of the many earlier threads that have touched on this issue; this one, for example.

See also John's article.

Meanwhile, what does 62353 actually say about the PE test current?

Using a test current of 25A is as likely to fuse together broken strands as it is to cause them to go open circuit. Then the fused joint passes the test but the joint is brittle and will fail within a short time.

Using a low current of 200mA is the safest option but ensure you flex the mains lead to see if the resistance alters. The Rigel 288 and Rigel 62353 have the patented current pulse, at the start of the test, to overcome the disadvantage of using the low test current. This overcomes the contact oxidisation of IEC connectors to reduce false failures.

Just a reminder, in the case of a live to earth fault you can expect over 100A to flow in order to blow the fuse in the required 0.4 seconds! Take a look at the time vs current curves for a typical 10A fuse and you may be surprised at what you find. This is the reason the mains supply impedance is as important as the protective earth continuity resistance.

Mains plug fuse curves (but only for 3 and 13 Amps, unfortunately).

Note the interesting list under "Interpreting Fuse Failure" farther down the page.

Good morning peeps!!!
Had a difficult Sunday here in Rome after yet another defeat at the feet of the Italians....Oh well...
As the Standard EN 62353 states it's still acceptable to use the 60101 protocol I've put together in Flukes Ansur a number of class 1 protocols that have a non recorded 20A PE test proceeding the 200ma PE test that goes on the final report,seems to give consistent result,best of both worlds,totally incorrect(the Italian jury is still out)????
Although using just the 200mA test gave rise to countless replacement mains cables this can't be considered a bad thing can it.