Washing Machines Failing PAT tests on High leakage

[martinxxxxxx]

I will name and shame the brands tomorrow. With some results too.

Martin

 

[ban-all-sheds]

Yes, something odd is going on here. I find it hard to believe that anyone is manufacturing machines for the UK market whose design is such that they are almost bound to fail the tests. Indeed, I wonder if they would even be allowed to sell such machines in the UK?

AFAICS they aren't failing any tests which apply to them per se, only exhibiting properties which have implications for their use in respect of a non-statutory BS which does not apply to them.

1) What does BS EN 60204 say?

2) If transitory behaviour by a filter is suspected, maybe a better way to measure leakage is to actually measure he current in the cpc while the machine is running?

 

[JohnW2]

AFAICS they aren't failing any tests which apply to them per se, only exhibiting properties which have implications for their use in respect of a non-statutory BS which does not apply to them.

That may be true - I just don't know what these 'P'AT rules are

AFAICS 1) What does BS EN 60204 say?

Again, I don't know - the BSI website wants my credit card number before it will tell me anything!

2) If transitory behaviour by a filter is suspected, maybe a better way to measure leakage is to actually measure he current in the cpc while the machine is running?

I don't think it's transitory (at AC - although it probably would be with DC testing). My understanding/suspicion is that it is persistant at AC, due to the filter capacitor - and we have been told that the (AC) test is undertaken whilst the machine is running.

I just don't know what the pass/fail rules for 'the test' are - or, indeed, whether the same rules apply to washing machines as would apply to truly 'portable' appliances.

Kind Regards, John.

 

[Monkeh]

AFAICS 1) What does BS EN 60204 say?

Again, I don't know - the BSI website wants my credit card number before it will tell me anything!

Go sign up with your library already. BS EN 60204 is freely accessible via a library subscription.

 

[martinxxxxxx]

Thank you for all taking an interest in this.

I am surprised that it has not come up before on other forums, searching the web revealed not a lot on it.

But there must be tons of WM being tested and I have seen a whole shop full of them either borderline or failing.

Is everyone else doing a leakage test I wonder?

 

[Grizzly]

Time to try and be helpful now

Are you using a PAT tester that performs a proper leakage test / protective conductor current test, with the appliance powered up to mains voltage, or is it a battery power only tester (for example the Seaward Prime Test 100), that performs a simulated leakage test at something like 40V ac?

This may have a bearing on it (then again it might not).

Another viewpoint: the IEE Code of Practice describes the protective conductor current measurement as "an additional or complementary test to the insulation test, for use if the insulation test cannot be performed or gives suspect results." (section 15.6, page 76).

So, as your washing machines have all passed the insulation test at > 20MΩ, is the leakage test necessary?

 

[sparkticus]

So, as your washing machines have all passed the insulation test at > 20MΩ, is the leakage test necessary?

Exactly! It seems to me (as others have suggested) that this is more or less a case of very acceptable insulation resistance during a DC test with a "slight failure" on an AC test that may not need to be performed if an insulation test is successful. The issue probably related to filter caps in the WM.

It would be good (interesting) if someone could post the exact list of PAT tests and the related parameters. PAT testing is not something I do. The last time I tested "portable equipment" was around 30 years ago when we simply looked at insulation resistance(if appropriate), polarity, fuse rating and physical condition. With a lot of portable equipment being double insulated, what tests are mandatory?

 

[Grizzly]

A basic list of the electrical tests can be found here:
http://www.pat-testing.info/test.htm

The IEE Code of Practice goes through the tests in much greater detail:
http://electrical.theiet.org/books/inspection-test/in-service-inspection.cfm

 

[STI]

A basic list of the electrical tests can be found here:
http://www.pat-testing.info/test.htm

The IEE Code of Practice goes through the tests in much greater detail:
http://electrical.theiet.org/books/inspection-test/in-service-inspection.cfm[/QUOTE]

Grizzly has posted the link and as i said the leakage test is not compulsory. Also i note that in some of the replies the figure of .75ma has been raised. for a washing machine which is classed as a stationary or movable appliance its 3.5ma or less. Dont know if that makes a difference when compared to your actuals.

 

[ericmark]

Grizzly has posted the link and as i said the leakage test is not compulsory.

The whole of the 17th Edition is not compulsory. We when inspecting and testing need to show if required in a court of law that we took all reasonable steps to ensure the safety of ourselves and others. Complying with the 17th Edition is one way to do this.

The problem is the 13A Plug we know from reading the 17th Edition that it is considered safe with a leakage of up to 3.5 mA. If we were to pay out for the spec on the plug we may find it is able to work with more than 3.5 mA but in real terms we would not want to stick out our neck and claim we have greater knowledge than the writers of the 17th Edition.

Where the item has no relays, timers or other devices which may take parts of the appliance off line while doing our tests we can of course use either insulation test or leakage test which ever is the easiest to do.

However where there are relays, timers and the like we must select a test that will test all functions. This may involve dismantling and testing individual parts and adding together the results, or using the leakage reading. Since with a washing machine it would be near impossible to test all parts without allowing it to complete a cycle while connected to a PAT testing machine then the only method would involve some dismantling. Because the tester could damage items the manufacturers service seclude should be followed rather then devise ones own testing criteria. This may well not ask one to test the whole machine.

The follow the manufacturers recommendations would show if required in a court of law that we took all reasonable steps to ensure the safety of ourselves and others. So clearly this is the method of getting around the problem. We service the machine to manufacturers recommendations and if the manufacturer has not asked for an insulation test to be carried out then we don't do the test. Should some one be injured we state in court we followed the manufacturers recommendations. That's us of the hook and the court would need to criticize the manufacturer not us.

However there is one problem. With the case in hand we know it will not pass and once we know it is wrong we can't unknow it. The moving finger writes etc. All I can suggest is he writes down failed requires service. And lets some one else service the machines who is unaware they will fail a leakage test.

I have for many years refused to test dish washers, washing machines, and freezers with frost free functions, and I always told the client these machines could not be PAT tested as such and required a maintenance contract instead.

Yes I know that many maintenance contracts in fact only attended when the machine stopped working but that was not my problem. It had a contract.

 

[martinxxxxxx]

Time to try and be helpful now

Are you using a PAT tester that performs a proper leakage test / protective conductor current test, with the appliance powered up to mains voltage, or is it a battery power only tester (for example the Seaward Prime Test 100), that performs a simulated leakage test at something like 40V ac?

It is a KT71 Kewtech Mains version, I have also tried the Seaward 2000 and a bettery version of the Kewtech.

This may have a bearing on it (then again it might not).

Another viewpoint: the IEE Code of Practice describes the protective conductor current measurement as "an additional or complementary test to the insulation test, for use if the insulation test cannot be performed or gives suspect results." (section 15.6, page 76).

So, as your washing machines have all passed the insulation test at > 20MΩ, is the leakage test necessary?

Thanks I will get the book again, the test centre "lent" us a copy to take the test with. And as I don't really like PAT testing I have resisted buying it again. But now that PAT testing is becoming a key to winning other work, I need to properly resource the activity and make sure I have the info to hand.

Martin.

I have found that in the past (last year) the the typical figure was about 0.6ma for washing machines so I am confused why we are getting such high results this time.

Martin

 

[sparkticus]

To get currents of 3.5mA and 10mA with 230V would require capacitors of at around 0.014 uF and 0.049 uF respectively - values which are in the ballpark of those found as filtering components.

I see that you are testing us John? It appears that you transposed the values to see if we were awake

 

[JohnW2]

To get currents of 3.5mA and 10mA with 230V would require capacitors of at around 0.014 uF and 0.049 uF respectively - values which are in the ballpark of those found as filtering components.

I see that you are testing us John? It appears that you transposed the values to see if we were awake

Is this a 'double test' (this time to see if I'm paying attention)?

Lower capacitance = higher reactance = higher impedance = lower current. (and the converse)

Kind Regards, John.

 

[sparkticus]

Lower capacitance = higher reactance = higher impedance = lower current. (and the converse)

Your logic is correct but isn't 0.014uF equal to 227,364.4 ohms at 50hz equal to approximately 1mA at 230V?

Or am I suffereing from decimalpointitis

 

[JohnW2]

Lower capacitance = higher reactance = higher impedance = lower current. (and the converse)

Your logic is correct but isn't 0.014uF equal to 227,364.4 ohms at 50hz equal to approximately 1mA at 230V? Or am I suffereing from decimalpointitis

Ah, right - yes, 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.

Kind Regards, John.