Could PAT testing cause damage??

[seasonalbiz]

Hi,

We had PAT testing carried out the other day and since the engineer left... one of the laser printers in the office has packed up. It powers up ok, and the green LED indicating its ready to print is lit... but it hasn't printed a page since the guy tested it, and it won't print a test page - so its defo a problem with the printer itself. Its only 2yrs old and its a Hewlett Packard Laser - I have always used HP printers and they have always lasted years.

I was quite surprised at the "crackle" noises made by the things he tested. I haven't contacted the company yet as I'm sure I'll get a load of flannel if I don't seek independent advise first.


Thanks.

 

[trev]

Has the link to the rest of the computer system been plugged back in?

 

[seasonalbiz]

Yeah, its all plugged up.

The printer should print a test page at the press of the "go" button (stand alone, no need to have a computer connected)... and it won't - so I know its a problem with the printer and nothing else in the chain.

 

[trev]

Can you try a different printer in the place of the one that "isn't working"

 

[KFH]

Yes PAT testing can cause problems but with modern equipment it is most unlikely. Normally IT equipment is given a reduced test which would be almost impossible to cause any damage.There should not have been any crackling noises from the equipment tested, was it from the tester? Unfortunately it is most unlikely that you would be able to prove that the testing had caused damage and it is unlikely that the tester could prove that he/she had not caused damage. When doing the earth bonding test on earth equipment it is possible to cause crackling (sparking) by not attaching the probe adequately but this would normally result in the equipment indicating a test fail.

 

[Engineer54]

Yes PAT testing can cause problems but with modern equipment it is most unlikely. Normally IT equipment is given a reduced test which would be almost impossible to cause any damage.There should not have been any crackling noises from the equipment tested, was it from the tester? Unfortunately it is most unlikely that you would be able to prove that the testing had caused damage and it is unlikely that the tester could prove that he/she had not caused damage. When doing the earth bonding test on earth equipment it is possible to cause crackling (sparking) by not attaching the probe adequately but this would normally result in the equipment indicating a test fail.

And if the Pat Test set the wrong value for the bond/screen tests???

 

[seasonalbiz]

There were no failures, and it seemed most equipment crackled when he was testing it. The kit he was using looked expensive... I think it was Megger.

 

[KFH]

If the tester had set the wrong values for the bond test he would have run a max of 25A through the CPC to the metal part the probe was on but at less than 12V. This would only be running through the earth path of the equipment, I would not expect this to cause a problem on modern equipment. It could cause a problem with the data side if it got onto that but that would imply a fault on the printer, though I have measured 100V on data cable earths in the past without any problems

If the probe is not firmly attached this that would crackle as it sparked. I can think of no other reason for the equipment to crackle but it is difficult to diagnose at a distance when we do not know what tests were run, what equipment was used and what test parameters were used. It is even possible but very unlikely that an electric strength test at 1,500V was run.

It is also possible the printer was about to fail and the test speeded it up a bit, but any modern piece of electronic equipment should be able to stand the tests without any problems as they are less severe than the production tests undertaken by the manufacturer.

Although I run PAT tests occasionally I do not generally like doing them on expensive electronic equipment as any problems like this become my problem even though I have run a soft test and done everything correctly. I have a clause in my contract saying I do not accept responsibility for faults especially as I do not do a function test before the test. Coincidences do happen.

 

[i=p/u]

it says for equipment ,your not sure about, consult manufacturer.... does this happen

 

[GLENNSPARK]

it says for equipment ,your not sure about, consult manufacturer.... does this happen

well you could consult the manual (if any)...but with the amount of folk about just trying to test stuff (hipot or otherwise).....doubt many calls are made to manufacturers.....

 

[i=p/u]

its very grey shady area, i have a job in march will be my first,,,, knoing my luck it will go bang.... unless i just soft testeverything,

 

[Engineer54]

If the tester had set the wrong values for the bond test he would have run a max of 25A through the CPC to the metal part the probe was on but at less than 12V. This would only be running through the earth path of the equipment, I would not expect this to cause a problem on modern equipment. It could cause a problem with the data side if it got onto that but that would imply a fault on the printer, though I have measured 100V on data cable earths in the past without any problems

If the probe is not firmly attached this that would crackle as it sparked. I can think of no other reason for the equipment to crackle but it is difficult to diagnose at a distance when we do not know what tests were run, what equipment was used and what test parameters were used. It is even possible but very unlikely that an electric strength test at 1,500V was run.

It is also possible the printer was about to fail and the test speeded it up a bit, but any modern piece of electronic equipment should be able to stand the tests without any problems as they are less severe than the production tests undertaken by the manufacturer.

Although I run PAT tests occasionally I do not generally like doing them on expensive electronic equipment as any problems like this become my problem even though I have run a soft test and done everything correctly. I have a clause in my contract saying I do not accept responsibility for faults especially as I do not do a function test before the test. Coincidences do happen.

Think you'll find there will be components of one kind or another connected to the earthed frames of IT equipment. One of the reasons for the very low earth bond/screen test current settings on IT compliant Pat Testers!!

 

[i=p/u]

was thinking that too, they connected to earrth

 

[GLENNSPARK]

Think you'll find there will be components of one kind or another connected to the earthed frames of IT equipment. One of the reasons for the very low earth bond/screen test current settings on IT compliant Pat Testers!!

yes and an IT tester dont do 200mA max earth bond for nowt...

 

[GLENNSPARK]

its very grey shady area, i have a job in march will be my first,,,, knoing my luck it will go bang.... unless i just soft testeverything,

well firstly you need to check that the appliance in question is:
A) flex not damaged
B) case not damaged
C) fuse present and of the correct rating
D) the class of equipment ( 1 2 or 3)
this is before you conduct any testing
class 3 or IT equipment should be earth bond tested at a max of 200ma (although most pat tester manufacturers set the test value at 100mA)