PAT testing televisions

[brg44]

I have just been given the job to do PAT testing where I work. Although I am not a qualified electrician I would describe myself as a competent person and have good knowledge of basic electrics.
Have read various articles saying to be careful when PAT testing equipment with sensitive electronics (tv's etc) and to test these at a current of between 20 and 200mA , or at an "IT" test position.
The PAT tester I will be using only has test buttons for Class 1, Class 2, and IEC. Have contacted manufacturer to ask about this.
I am worried I may damage some televisions if there is no way of limiting the current.
Any help much appreciated.

 

[plugwash]

What make and model is this pat tester? do you have a manual for it?

In general electronics with filters in musn't be flash tested. Having said that generally you shouldn't be flash testing during routine PAT tests anyway as repeated flash testing is not good for the insulation.

A standard 500V insulation test should be ok on any properly built equipment but could potentially do serious damage to say a computer with a faulty PSU. High current earth bond tests can damage equipment with bad earthing.

Because of this many testers have an "IT" setting that tests at lower levels that should still find faults while being less likely to do further damage to equipment.

 

[disinfo]

Does your company have an insulation resistance tester?

You can perform 200ma continuity checks with one if your PAT tester doesn't do it.

 

[STI]

Normally a 500v insulation test does no harm to a TV, whether Plasma, LCD or CRT (Not had a LED one to do yet).
As plugwash asks what machine do you have. I dont want to teach granny etc but do you understand when to use the Class1, 11 IEC etc. I also would not use your tester on IT equipment unless you can drop the IR test down to 250v

 

[brg44]

Many thanks for all your replies and the manufacturer has come back to me and said that all tests on this Tele-Products PAT-IT tester is done at 100mA.
I am ok with Class1, Class2 and IEC .

 

[ericmark]

612.2.1 Continuity of protective conductors,
including main and supplementary equipotential bonding
A continuity test shall be made. It is recommended that the test be carried out with a supply having a no-load voltage between 4 V and 24 V, d.c. or a.c., and a short-circuit current of not less than 200 mA.

Not sure it complies then? Although this refers to installation the "Testing of in-service electrical equipment" I am sure recommends 25A and a 100ma test is unlikely to high light any poor connections.

 

[Grizzly]

Not sure it complies then? Although this refers to installation the "Testing of in-service electrical equipment" I am sure recommends 25A and a 100ma test is unlikely to high light any poor connections.

Never mind BS7671, it's the CoP that matters!

IEE Code of Practice for In-service Inspection and Testing of Electrical Equipment (3rd Edition), section 15.4 (pages 73 - 74).

Either the 'Hard' earth continuity test (test current not less than 1.5 times the rating of the fuse, upto a max of about 26A) or the 'Soft' earth continuity test (test current within the range 20mA to 200mA nominal) is applicable.
Obviously the 'Hard' test should be used with more caution, depending on the type of equipment under test.
Both test should include an inspection of the flexible cable terminations at the equipment and the plug or flex outlet, and the cable should be flexed while the measurement is performed.