PAT Testing failures

[DJ Jules]

I've just had my kit PAT tested by a new guy with a sparkling new machine.... and it's failed a whole load of my kit on Earth Leakage.

I'm interested to know if anyone else has had similar problems with similar kit, and what they've done about it. The failures don't appear to be caused by equipment fault as the numbers are consistent between both of the RCF's, so it seems to be something to do with the equipment design. The kit which failed was:

2 x RCF ART 422A speakers - 49 microamp leakage (consistent for both speakers)
1 x BENQ DLP Projector - 34 microamp leakage
1 x Mackie 16 channel desk - 1milliamp+ leakage

All of the above are class II insulated equipment. The above figures didn't change on re-test either. Failure is apparently anything above 30microamps of leakage between live/neutral and earth.

Thanks in advance,

Julian

[musicologydisco]

That sounds suspicious to me. I know it's further expense but I would get a second opinion. It's either earthed or it's not as far as I understand. Never heard of "leakage".

[DJ Jules]

There seems to be three tests which are done now:

1. For class one equipment (e.g. with a metal shell) then they test Earth continuity which is the resistance between the earth pin on the plug and any exposed metal parts on the kit.

2. For both class one and two they now test earth leakage (the amount of current that "leaks" between live/neutral pins and the earth pin on the plug). If this number is too high, then it'll trip out the RCD at the fuse box (though admittedly more like 30ma not 35microamps) .

3. For both class one and two they also now seem to test insulation resistance which apparently should be the resistance between the live/neutral and the case.

Interestingly... this is the guys tester

Julian

[deltic]

the seaward prime test 100 is only a very basic tester, and not the best for sensitive IT/audio equipment , don't even think it has a setting for sensitive equipment.

i would get your kit re tested by somebody with a proper tester.

[coley]

how the hell can somebody with £100 tester say a state of the art electronic device is unsafe to use. as soon as the cabling enters the enclosure it wired to a transformer. I am I right in thinking this

[DJ Jules]

How the hell can somebody with £100 tester say a state of the art electronic device is unsafe to use. as soon as the cabling enters the enclosure it wired to a transformer. I am I right in thinking this

Nope, you're wrong. All the kit which failed uses Switch mode power supplies which are a lot more complicated than transformers (think high efficiency computer style power supplies, not big lumps of ferrite wound with copper) They have a lot higher earth leakage currents than traditional transformer based kit as the earth is probably connected to one of the power rails on the low voltage side of the supply (as opposed to just being connected to the case). The tolerances on the testing kit are incredibly low though and the currents we're talking about are tiny. As an example, the IEC lead had a 10 microamp leakage (through it's insulation) and the failure current is only 3 times this value (30 microamps).

And the tester is £269

It's interesting that they're even doing these kinds of tests on Class II insulated kit as the tests used to just be a visual inspection of cables/housing and nothing else.

I think I'll get a second opinion, but if the second guy turns up with the same tester, then I'm likely to have the same problem

Julian

[Corabar Entertainment]

I may be talking complete, total and utter rubbish here, as I do not profess to know anything whatsoever about the subject matter, but I do know that Steve often has problems getting a decent connection for the earth tests - often because the screws are painted - meaning that it gives a false 'fail' report.

[MikeW]

I may be talking complete, total and utter rubbish here, as I do not profess to know anything whatsoever about the subject matter, but I do know that Steve often has problems getting a decent connection for the earth tests - often because the screws are painted - meaning that it gives a false 'fail' report.

Just had my pat testing done and that was one of the main problems.

[DAVESOUNDS SERVICES]

Sounds like your tester should read this
Table 3: Maximum permissible protective conductor current
Appliance Class Maximum Current note (1)
Portable or hand-held Class I Equipment 0.75 mA
Class I heating appliances 0.75 mA or 0.75 mA per kW, whichever is the greater, with a maximum of 5 mA
Other Class I equipment 3.5 mA
Class II equipment 0.25 mA
Class III equipment 0.5 mA
Table 4: Additional requirements for equipment having higher leakage current
Permanently wired or supplied by an industrial
plug and socket-outlet
Protective conductors
Label The equipment should have a label bearing
the following warning or similar wording
fixed adjacent to the equipment primary
power connection (based on clause 5.1.7 of
BS EN 60950)
Has he got the current COP Code of Practise or is he a "60 quid sid" Tester?
some quality gear has filters and caps that dump noise to eath so test up pretty poor to the untrained eye.

Hope that helps any problems pm me Cheers

JUST LOOKED TOO RCF speakers aint class2 they are 3 wire metal bonded to earth,,,CLASS 1 THINK the projector is too
Better ask for a refund and find a better tester . Sorry i dont cover your area,

[Corabar Steve]

What tester do you use Dave?