ir testing

[wolfiehogan]

hi guys i have to do an ir test tomorrow but my problem is that there are appliances connected as it is an existing installation. basically i want to test an installation but has a plc connected that controlls alot off the circuits that are in the fuseboard. if i join the l + n and test to earth will this save the plc compondments from damage.
as i did this the other day and there was a fluoresence light connected and it brought down all the readings and when i dis connected the light everything was fine. hope some body can understand

 

[IQ Electrical]

It's the preferred way of IR testing on a periodic inspection on other than small domestic installations.

Some fixed equipment and surge protection devices can still affect readings though.

You don't sound like you've done much testing?

 

[wolfiehogan]

no not done alot off testing am only familar with domestic unfortnately. and am afraid off damaging the equipment and can not just disconnect it as it controls a lot off the installation. is it ok to test it the way i mentioned and if it is then how come the pluoresence brought down my readings before

 

[IQ Electrical]

Did the fluorescent have an integral emergency light?

I'm assuming you didn't test L-N on the fluorescent? If you did then you're just seeing a reading influenced by the ballast/control gear.