Washing Machines Failing PAT tests on High leakage

[sparkticus]

I'm guilty, but not what I was being accused of (transposition). My decimal point was wrong, and the 10mA one should been approx 0.14 uF, not 0.014 uF. Thanks for noticing this. However, my conclusions remain the same.

Yes your conclusions are the same and correct I believe, though 0.049uF is equal to approximately 3.5mA. I only raised it because I thought you may have been conveying out of order fibonacci numbers providing a cryptic clue to the location of the holy grail which is what happens when you watch the DaVinche Code too may times as I probably have

 

[JohnW2]

I'm guilty, but not what I was being accused of (transposition). My decimal point was wrong, and the 10mA one should been approx 0.14 uF, not 0.014 uF. Thanks for noticing this. However, my conclusions remain the same.

Yes your conclusions are the same and correct I believe, though 0.049uF is equal to approximately 3.5mA. I only raised it because I thought you may have been conveying out of order fibonacci numbers providing a cryptic clue to the location of the holy grail which is what happens when you watch the DaVinche Code too may times as I probably have

Indeed - I made a general hash of it Just to be clear, at 230V 50Hz, the 'leak currents' should be 3.5mA with about 0.049 uF and 10mA with about 0.14 uF.

Kind Regards, John.

 

[ericmark]

The whole question is should a washing machine be PAT tested or Serviced.

I would like some one to explain how one uses a standard PAT testing machine to test an item with timed functions which can take hours to complete?

The pump to empty the machine only runs at the end of the cycle and one would need to run the machine to this point in order to be sure there was not a fault with the pump.

I would agree the 3.5 mA limit does exist for items using a 13A BS 1363 plug and the test has highlighted a problem with the machine. However I also noted this problem with some items and the top of range Robin PAT tester would fail items as a result. But using the very basic Robin machine with analogue meter it was realised this was just a peak on switch on and as it was left connected this dropped to well within acceptable limits.

Which returns us to original question PAT testing or servicing and I strongly believe the machines should be serviced rather than PAT tested as this would also ensure the removal of any fluff build up which is more of a danger with fire a big problem with machines of this type. Plus of course unless using LG checking the belt for wear and tension.

LG are odd ones out and are the only main stream washing machine able to run on an inverter. In the main this is because the whole machine runs on an inverter and AC is converted to DC and back to AC and I would expect as a result some problems with PAT testing these machines as they should not of course be subjected to the 500 volt insulation test.

So I ask again does the service manual for the machines in question ask for a leakage test or a insulation test and were the machines tested as laid out in the service manual?

 

[JohnW2]

The whole question is should a washing machine be PAT tested or Serviced.

I agree. In fact, until this thread appeared, I didn't realise that people did attempt PAT tests on items of this sort.

The pump to empty the machine only runs at the end of the cycle and one would need to run the machine to this point in order to be sure there was not a fault with the pump. ... I would agree the 3.5 mA limit does exist for items using a 13A BS 1363 plug and the test has highlighted a problem with the machine.

True - but, again, it's a question of what the 'PAT' test is meant to be testing. In fact, if the machine fails on the basis of the 3.5 mA criteria, then I imagine that one presumably wouldn't need to undertake tests that would identify pump faults - I imagine that, as far as 'PAT' testing (as opposed to servicing) is concerned, a fail is a fail - so there's probably no obligation to look for further problems once something has already failed!

I think the bottom line is, as you are implying, is that 'PAT testing' is just not suitable/appropriate for appliances of this sort.

Kind Regards, John.

 

[ericmark]

I think the bottom line is, as you are implying, is that 'PAT testing' is just not suitable/appropriate for appliances of this sort.

Spot on. In a nutshell.

In fact, if the machine fails on the basis of the 3.5 mA criteria, then I imagine that one presumably wouldn't need to undertake tests that would identify pump faults.

Agreed but how can one pass?

To test a freezer I would unplug it do rest of tests and then do it last in the hope by that time it would have warmed up enough to be on run cycle. I would query any results with very low run current as clearly not switched on jurying the test. I considered the more done with machine the better as once one has to start to dismantle to test it becomes expensive. But as the frost free freezers came out there was a problem with testing.
1) We did not know how the defrost was done. Could be motor reverse or a heating element and if latter then since likely it was a mineral insulated job high chance of earth leakage.
2) The time involved mean one could not really offer a fixed price for testing items like this.

So the only option was to decline to test items of this type.

This left a second problem in that every few years the installation was tested and also all hand held, and small portable but there was a residue of items which were never tested. Clearly this needed to be re-dressed. As a manager one has to show that all reasonable care has been taken to ensure there is no danger and either one has to learn how each individual item works and how to test it, or accept that one needs a specialist to test certain items. The latter is easy way out. And some times only way out with items like vending machines. However as the manager one does have to ensure the people you hire are able to do the work. Getting some one who just sticks on a label is hardly enough. But each item of plant in the register will have an entry against it if only to say "Under maintenance contract".

What I am guess is the manager in this case has seen "martinxxxxxx" as a soft touch where he can off load his responsibility onto some one else at a fraction of the cost to getting a proper maintenance contract.

However giving "martinxxxxxx" he's due he has seen at least some of the problems and has refused to rubber stamp all the items and just make a quick buck.

But of course it is very hard to say "Made a mistake with that job need to drop it even if it costs me." Especially when one sees the chance of it growing to more work. And like "martinxxxxxx" I would also try to resolve the problem if I could.

I seem to remember the hire trade is slightly different to rest in that every machine is re-tested before re-hire even if the time limit has not expired. If I was caught up in this I think I would tell the client I would pass items with between 3.5 and 4.5 mA but with a 3 month only ticket purely to give him time to get the proper maintenance schedules. But once the 3 month ticket had expired would not re-pass until replies had been received from the manufacturers to say what should be done.

Not really what should be done but he needs to show the client he is trying to help rather than being pedantic in any way.

 

[JohnW2]

I think the bottom line is, as you are implying, is that 'PAT testing' is just not suitable/appropriate for appliances of this sort.

Spot on. In a nutshell.

In fact, if the machine fails on the basis of the 3.5 mA criteria, then I imagine that one presumably wouldn't need to undertake tests that would identify pump faults.

Agreed but how can one pass?

As I said, it depends upon 'what' it has to pass. If many/most/all washing machines have L-E filter capacitors such that it is inevitable that more than 3.5 mA will flow when mains voltage is applied, then I find it hard to believe that there is a requirement for them to pass a test which requires <3.5 mA. That's why I think that the wrong test is being undertaken.

I think we've already been told that, as far as 'PAT' testing is concerned, the 'leakage current' test is not compulsory, provided that IR is OK - so are we perhaps inventing a problem (as far as PAT testing is concerned, not necessarily BS7671) which doesn't actually exist? Indeed, perhaps the non-compulsory status of the 'leakage current' test exists for this very reason?

Kind Regards, John.

 

[ericmark]

I think we've already been told that, as far as 'PAT' testing is concerned, the 'leakage current' test is not compulsory, provided that IR is OK

Correct but to do a IR test involves dismantling. It is pointless doing an IR test with items switched off. Also one should not do an IR test on filters so only alternative is a leakage test. So since we can't do an IR test then we must do leakage test so back to square one.

 

[JohnW2]

I think we've already been told that, as far as 'PAT' testing is concerned, the 'leakage current' test is not compulsory, provided that IR is OK

Correct but to do a IR test involves dismantling. It is pointless doing an IR test with items switched off.

I know you've said that a number of times (and I accepted it at the time), but having now thought a bit more, I wonder how true it actually is. Provided one does 'the full set'of IR test (L-E, N-E and L-N), and provided that (which I imagine to usually be the case) internal switching is single-pole, one should pick up most problems, . Consdiering the drain pump you previously mentioned - if there were any IR problem, it should normally show up on the N-E IR test, even when the L side is disconnected by an SP switch/relay.

Also one should not do an IR test on filters so only alternative is a leakage test.

That's an interesting point,particularly given that the OP said that he had undertaken IR tests on the machines in question. I would suspect that a capacitor rated for 230/240 V AC or higher would probably tolerate 500 V DC (if that's what was used for IR tests) without damage, but that's probably not a certainty - so I wonder if it's possible that the OP damaged supply filter capacitors in all of his machines with initial IR tests. A test of that would obviously be for him to examine a machine that he hasn't previously touched - and then do a 'leakage current' test first, followed by the IR test and then another leakage test. However, I rather doubt that will be the problem.

Kind Regards, John.

 

[ericmark]

I know you've said that a number of times (and I accepted it at the time), but having now thought a bit more, I wonder how true it actually is. Provided one does 'the full set'of IR test (L-E, N-E and L-N), and provided that (which I imagine to usually be the case) internal switching is single-pole, one should pick up most problems, . Consdiering the drain pump you previously mentioned - if there were any IR problem, it should normally show up on the N-E IR test, even when the L side is disconnected by an SP switch/relay.

This again returns to manufacturers and their service seclude. Without their manual how do you know it is single pole switching? If designed for Europe then since the German plugs can be plugged in either way around then likely double pole relays. If designed for UK then unlikely to be an issue with 3.5mA limit.

It would be interesting to see the mA limit for the CEE 7/4 (German "Schuko" 16 A/250 V grounded) plug wonder if it's higher than the British BS 1363 (British 13 A/230-240 V 50 Hz grounded and fused), equivalent to IS 401 & 411 (Ireland), MS 589 (Malaysia) and SS 145 (Singapore), SASO 2203 (Saudi Arabia) plug.

 

[martinxxxxxx]

Just a note to say the Beko and Hotpoit new ones fail mostly at about .87 to 1.2 mA.

Will add a table of results soon

 

[STI]

Just a note to say the Beko and Hotpoit new ones fail mostly at about .87 to 1.2 mA.

Will add a table of results soon

But that result is a pass its <3.5mA

 

[JohnW2]

Just a note to say the Beko and Hotpoit new ones fail mostly at about .87 to 1.2 mA.

But that result is a pass its <3.5mA

That's certainly what the OP told us - limits of 0.75 mA for handheld, otherwise 3.5 mA, and I don't think many hands could hold a washing machine!

Kind Regards, John.

 

[Ric2013]

martinxxxxxx wrote:
Just a note to say the Beko and Hotpoit new ones fail mostly at about .87 to 1.2 mA.
But that result is a pass its <3.5mA

That's certainly what the OP told us - limits of 0.75 mA for handheld, otherwise 3.5 mA, and I don't think many hands could hold a washing machine!

Kind Regards, John.

So, was this entire thread a false alarm then?

 

[bernardgreen]

So, was this entire thread a false alarm then?

It may have been when it was last posted PostPosted: Tue Sep 06, 2011 11:24 am Post Subject: