Posted By Martin Cole Hi To All I was very pleased to recently take up the post of caretaker in a medium sized Family Medical Centre, part of my duties include Portable Appliance Testing which I passed the exam for just this week. Apart from the usual portable appliances that you would expect to find in the offices and treatment rooms there is also approximately 35 computers with flat screen monitors and laser printers connected which are all relatively new. My manager insists that the person employed in the same position before me always PAT tested the old computers, monitors and printers, indeed I have come across some old IT equipment tucked away with PASS stickers on them. I must admit that this is worrying me a little as the trainer on the PAT course said that you never test sensitive equipment such as computers and monitors etc, he said that the equipment test should be purely visual and just PAT the mains lead, which to me makes sense. I have tried several sources to try and clarify the position and get some recommendations but everywhere appears to skirt around the subject (which is even more worrying, if professionals don’t want to talk about it, then what chance have I got?). Anyway I have ordered a couple of books from Amazon, which I’m hoping will help me to sort it out. In the meantime I have come across this great website full to the brim with intelligent knowledgeable people who are happy to share their wisdom and offer advice when asked, so I wonder if anybody can advise me on the testing of IT equipment, does it need testing? should I or shouldn’t I test it? if I should test it, then please could you describe how, the thought of putting 25amps through IT equipment scares me to death, although the tester I’m using does have an 8amps option. I’m sorry if this is a bit long winded before getting to the point but I would really appreciate it if anyone could help me with any of the above. Thanks in advance, Martin.

Posted By Dave Daniel I was Group Safety Adviser for Rover Group for 11 years in the 1980's. When the electricity regs came in I did a trawl through our accident databases and records. In 10 years over a workforce of 50,000 we found zero instances of electrical accidents to equipment users despite the abuse some equipment was given. We did however find 4 examples of "qualified" electricians being injured "hot-wiring" 440v fuseboxes, and one gentleman at a foundry who tried to saw through the live main 11Kv supply to No.2 Cupula to steal the copper (he survived). My conclusion then and now is that although PAT testing may well find some faults, few of these are likely to result in injury and most are visually obvious. As far as computers go, I would not normally recommend these or similar low-risk equipment being PAT tested. I do not think the level of risk justifies it.

Posted By Jim Tassell Paul Martin is right - see HSE guidance. Equipment like computers have filters on the mains input to protect against mains-borne interference. These have limited tolerance to over-voltage and can get zapped by some PAT tests. So that's why you were advised not to do anything more than a visual exam of the computer box and monitor. And I agree with others, it's the mains lead that gets the wear/trapped under desks/pulled/tripped over, so concentrate on that end. Jim

Posted By Ron Hunter inappropriate PAT testing of IT equipment can cause damage which may then lead to that equipment causing voltage 'spikes' to propogate into the ring mains. This will in turn potentially upset other sensitive electronic equipment. This is of course assuming the equipment still works at all. High voltage PAT testing will potentially destroy in-line capacitors intended to allow internal switched-mode power supplies to operate properly. Incidentally there are risks involved with potentially lethal leakage currents developing in computer workstation equipment powered from multi-way extension cables where a fault condition occurs. Section 607 of Part 6 of the IEE Wiring Regulations refers.

Posted By t.segaran Hi Martin, Sorry to be a dissenting voice, but all IT equipment can be quite safely tested as long as a low current is used. It is the Earth Bond test current that causes a problem. The IEE regs allow a current between 20 and 200 mA to be used for this. You may get a fail for the Insulation Resistance as this is done at 500V. This happens if there are surge protection devices fitted. However this can also happen with surge protected mains extension leads and not just with IT equipment. There are many PAT testers available that have a low current test facility for Earth Continuity. These are routinely used to test IT equipment on a regular basis. Regards Seggy