Act 6 dimmer pack PAT test failure.

[J Pearce]

11 hours ago, dave-w said:

Our PAT tester is saying he won't pass the dimmer unless the LINE can be shown to be "sufficiently" insulated from Neutral and Earth combined.

It's refreshing to hear of a PAT tester that actually knows what the test is checking, rather than just saying 'it won't pass the test, it keeps failing' and chopping the plug off.

[kgallen]

This is an interesting result. The "failure" doesn't appear to be due to an equipment fault, but as designed.

I'm not sure how I feel about modifying the factory build by removing "safety" components to satisfy this test. In particular this equipment is classed as for "professional use only" and consequentially for the use of "instructed persons (electrically)" rather than "ordinary persons". In which case, as a piece of professional equipment under the control of an instructed person (electrically) that has "high" leakage current, I would have thought, that having demonstrated there isn't an equipment fault, this result could be documented and the equipment passed. If I understood your results correctly, the leakage current will be 230V/330kOhm = 0.7mA, so below the 1mA threshold that would be acceptable for an earth leakage test and one that BS7671 doesn't consider a high protective conductor current, the threshold being 10mA, Reg 543.7.1.202, above which special earthing arrangements need to be made (Reg 543.7 in general).

However... that you've confirmed that the equipment is supplied by a 13A plug, rather than say a 32A or 63A ceeform, indeed muddies the water as it makes it easier for an "ordinary person" to energise the equipment and also for that "high" leakage current to present itself on the protective conductors of a wider radial or ring circuit. Would it be viable to use say a 16A ceeform (with min 2.5mm2 flex) instead? This would satisfy BS7671:2018+A2:2022 Reg 543.7.1.202 (ii) for connection of equipment with "high protective conductor current" (although your <1mA is substantially less than the 10mA triggering this Reg).

As mentioned above, at least you do seem to have a knowledgeable and engaged tester.

..from a bloke just on the web.

[dave-w]

Yes I share your concerns kgallen.  But given that the later PCB does not have these resistors, I am a bit more relaxed about removing them.  In the absence of an "official" circuit diagram for PCB 881/2 (which I cannot find) I do not expect our PAT tester to grant a waver especially as I have already shared the Act 6 manual guidance quoted by Edward above, which talks about a minimum of 1.7meg to earth (equivalent to about 0.15ma earth leakage current at 250V?)

I shall mention the 1ma earth leakage test current to our PAT tester as he has already offered to retest at 250V.  Maybe this will give him the leeway he needs.  Otherwise its out with the soldering iron!

Changing plugs is not really an option for intermittent use in a church hall. 

In passing, it seems rather surprising that this is apparently not a known issue for early Act 6's.

[indyld]

1 hour ago, dave-w said:

In passing, it seems rather surprising that this is apparently not a known issue for early Act 6's.

This may be overestimating the number of these Act 6s still in existence that also find themselves under scrutiny from an ISITEE...

Isn't the test minimum 1Meg whichever test voltage is used? (for ISITEE, not 7671 installation).

Edited July 4 by indyld

[KevinE]

the max current through the earth conductor in a class-1 portable appliance supplied via a 13A plug is now 5ma, it's been upped from 3.5mA. If a 16A plug is used it can go to 10mA, anything more requires a permanent supply.

 

At least that's how I interpret it. Recently I repaired an industrial food mixer and it had a leakage of exactly 10mA but was supplied with a 13A plug. I spoke to the manufacturer and they said it was designed for a 16A industrial plug/socket arrangement and the leakage was both normal, by design and permissible. The owner of the mixer had wired his own 13A plug as he didnt have any 16A outlets in the kitchen. I passed the info on.

 

 

[indyld]

5 hours ago, dave-w said:

Changing plugs is not really an option for intermittent use in a church hall. 

Although the tester seems to be focussed on the IR test ( not earth leakage as being discussed in various posts here) surely if a different plug was needed to squeak through the latter then just do so and make a jumper? Hire companies have plenty of 13A > 63A 1ph for similar purposes.

Then the items are tested individually.

[kgallen]

Just to corroborate Kevin's statement, as I know the forum like a reference to "official" requirements!

1 hour ago, KevinE said:

the max current through the earth conductor in a class-1 portable appliance supplied via a 13A plug is now 5ma, it's been upped from 3.5mA. 

The 5th edition of the IET ISITEE CoP Section 10.7 has a single requirement of 5mA for maximum protective conductor current/touch current.

The earlier 4th edition of the ISITEE CoP has Table 15.3 which specifies 0.75mA for portable or hand-held Class 1 equipment and 3.5mA for other Class 1 equipment.

 

[dave-w]

Found this, which seems to be very relevant.  

PAT Testing - Leakage Current Test (pat-testing-training.net)

The problem R/C bridges could well be EMC protection rather than capacitor discharge and these fall into the category calling for Earth Leakage Test rather than an insulation test as suggested by kgallen above.

I have brought this to the attention of our PAT tester in the hope his equipment can oblige and avoid my having to remove intentionally present components.

[chelgrian]

7 hours ago, indyld said:

This may be overestimating the number of these Act 6s still in existence that also find themselves under scrutiny from an ISITEE...

Isn't the test minimum 1Meg whichever test voltage is used? (for ISITEE, not 7671 installation).

We have two later DMX ones kept in PAT and three D54 ones and one analogue one we want shot of 🙂 Ours are all on 63A Ceeform though.

[dave-w]

Our PAT tester appears to be receptive to the EMC circuitry approval requiring Earth Leakage test rather than Insulation test.

I am meeting him Tuesday coming for a reassessment.  Could be a win-win.  He passes it and I don't have to remove any components!  

Thanks all for the inputs. I will report back.

[kgallen]

Thanks for keeping us up to date. Let us know how it goes! And get it documented for the next PAT!

[KevinE]

He might need to learn about class-Y varistors as well. These are also connected between L/N and earth and will not leak any current while powered but will fail a 500V insulation test every time.

They're not that common but are growing in popularity.

[David Duffy]

Class Y varistors ?

[KevinE]

indeed. L to earth and N to earth. 

[David Duffy]

I've not heard the term class Y varistor.