What to PAT test

[zacazoom]

Could someone help, Been doing some reading on what you can pat test, I understand they say you can pretty much test anything with a plug, however does this also mean DC appliances and if so what tests would I perform, would I still perform a 500 V or 250 V test. Also would you test say a mobile phone charger and then with the phone attached and again what tests would I perform.

Thanks

 

[acat]

Anything with a plug on it that is single phase or three phase if you have the adaptors. Mobile phone charger yes mobile phone no.



Chris

 

[zacazoom]

What about a ordinary digital phone that sits in a DC cradle. Would I not test it with the phone in the cradle.

So just to confirm, if I had a DC adapter connected to an appliance to make it work constantly that does not have a battery, I could test this without a problem and the amount volts and I could test on could be 500 V ins res providing it meets the relevant Britsh standard.

Thank you for your response

 

[acat]

At a push you could do the plug that goes into the mains socket. If you test the phone itself you may blow it. Dont forget any sensitive equipment like computers, photocopiers, cash tills, etc etc have to have a very low current or you will blow them up.



Chris

 

[Deleted member 9648]

You cant test items like phone chargers and phone cradles....there is nothing to test as they are class 2 with no exposed metal parts.....a visual inspection only is appropriate.

 

[acat]

Dont agree class II equipment is not just visual, insulation test, operation test earth leakage etc are all carried out. The only test left out is the earth bond test for obvious reasons. It is only if it fails the visual that you would not carry on.





Chris

 

[zacazoom]

So i could test it as if it was IT equipment , For example the 100mA test, but not do the insulation resistance test.

 

[acat]

Have you got a copy of the code of practice. Dont test the phone the plug that goes into the socket class 1 or class II does not matter that needs to be tested, same with mobile phone its just the charger. If either had a leakage to earth that was not picked up on the visual and you took the plug out without switching the socket of you would become the earth path.





Chris

 

[Deleted member 9648]

Can you please explain acat how to do an insulation test on a class 2 appliance with an all plastic case ,and what such a test would achieve?
You can only insulation test a class2 appliance if it has exposed metal parts,using an auxillary probe from the pat tester onto the metal parts.

 

[rodney12]

Think you may be a little confused, if it has exposed metal parts it should be class I, not II.

With regards to ins res test on a class II appliance you just plug it in you tester and bobs your uncle

 

[Risteard]

I would have thought that a visual inspection only would be appropriate.

Incidentally, the insulation resistance test tests live conductors connected together (i.e. line and neutral) to earth. If there is no cpc, what would this achieve?

 

[zacazoom]

I think I have read somewhere , you test ins res on class II and you connect the test probe to a joint or potential weak area of the insulation.

So going back to the DC charger/adapter would I do a visual, ins res at 500V, but i can't do any other test, can't do earth bonding, because there is no earth, can't do operation test earth leakage because I would have to attach the appliance to the charger/adapter in order to do this. But I guess this test should be OK on sensitive equipment because it is actually only swiching on the appliance and it works out the leakage.

Is that right.

 

[Deleted member 9648]

Think you may be a little confused, if it has exposed metal parts it should be class I, not II.

With regards to ins res test on a class II appliance you just plug it in you tester and bobs your uncle

I'm not at all confused,you are I'm afraid.
There are many class 2 appliances in use with exposed metalwork which is protected from contact with live parts by double insulation, an electric hammer drill for example. A pat tester carries out an insulation tests between the earth pin and the L and N pins connected together,therefore just plugging in a class 2 appliance and pressing test will do sod all as there is no earth conductor.For this reason pat testers are supplied with an auxillary probe,in the case of a class 2 appliance with exposed metalwork the plug is connected to the pat tester and the probe onto the metalwork and the test is then carried out. The probe takes the place of the absent earth wire.

For the same reason it is utterly pointless plugging in an all plastic phone charger to a pat tester and pressing test.....think about it.

 

[Risteard]

Yep, the only time it serves any purpose is if there is exposed metalwork then connecting the probe will help to demontrate that it is segregated from live parts, which for a Class II appliance must be by double or reinforced insulation.

 

[sparkswillfly]

get your the essential guide to pat testing by barry atkins on ebay etc it tell and show all the info you need to know and is well worth the investment to do it correctly and to the book

 

[acat]

The test is carried out between live conductors, ie phase and neutral, connected together, and the body of the appliance.. (quote from guide)


page 75 in service inspect and test table 15.2 gives the readings which for class II is 2.0Mohms.


Hope that helps




Chris

 

[zacazoom]

Hello acat,

So would you think in the case of a charger, do we do 500v ins res put the probe on the casing and dont do any other test , load etc because I cant connect the phone to the charger and test , becuase it may damage the equipment.

Thanks

 

[Deleted member 9648]

In the case of a class I or class II appliance the body of the appliance woulld need to have exposed metal parts for an insulation test to be carried out.
Might be wrong but I think the minimum IR for a class I is 2 megohms and 7 megohms for a class II.

Hello acat,

So would you think in the case of a charger, do we do 500v ins res put the probe on the casing and dont do any other test , load etc because I cant connect the phone to the charger and test , becuase it may damage the equipment.

Thanks

So you are going to put the probe on an all insulated plastic case ???

 

[acat]

Page 75/76 of the guideexplains the tests and if you look at table 7.1 on page 34 it gives a scedule for formal visual inspection and a second row for combined inspection and testing for class II equipment its only in hotels offices and shops where no testing takes place.



Chris

 

[zacazoom]

Many Thanks