PAT testing

[Andy Dingley]

Supplier validation should pick that up: don't use crap suppliers. This is why I just never buy any Ring product.

[ARWadsworth]

I found these Andy

[Man at B&Q]

That's just some local jobsworth imposing their own idea of elfin safety. I've found exactly the opposite, where newly bought items specifically did not need to be tested until the next scheduled visit of the tester.

MBQ

[whisky-dave]

A few years ago a few of our bench power supplies failed the PAT test for earthing as IIRC the resistance required for the Earth conductor had been lower. On those PSU that failed I just kept shortening the mains lead until they passed. I also had to file away at the case to make sure of earth continuity. Eventually I gave up and refused to do it, and suggested they get some upto date equipment that would pass, rather than me doing stuff to pass it. These units were from the early 80s.

[whisky-dave]

we had that problem too, the main problem was teh number needed to be tested, we weren;t talking about a few plugs here and there. With 100-200 new students each year in our dept alone and one person being given one day a weeek to do all PAT'ing (include 7,500 appliances in the dept.) it got too difficult. And there was the problem of what if while testing it damaged the computer, especially where insulation tests are used.

I think we've given up now, all I do is a visual check I couldn't even get a decision on whether or not we should allow shaver socket adapters that students use with their two pin laptop PSUs. I have stopped one student using a pen in the earth socket so he could jam in his two prong plug in to 3 pin bench socket. But at least the lab is RCD protected.

[Andy Dingley]

You're not allowed to complain unless you're in a chemistry department. The shortages and hacks those guys are having to put up with are quite staggeringly bad these days. 8-(

[whisky-dave]

So are those that tell you your equipment has failed the test so buy new kit.

[Mike Harrison]

Assuming it is genuine....

[Huge]

Chemistry department? Wossat? (The Chemistry department at my alma mater got eaten by biochemistry decades ago ...)

[Owain]

The biochemistry dept at mine got eaten by Environmental Science ...

Owain

[Andy Dingley]

this case, plain dishonest). There's nothing wrong with sourcing through eBay, but you have to apply appropriate levels of inbound inspection according to where you got it.

[Bob Eager]

It's "Biosciences" now!

[The Real Doctor]

I tried to persuade my employers that they only needed to test the power supply on my laptop, since that is the only bit which runs on

240V - the laptop itself is a nice, safe, 19V device. They didn't accept this.

Ian

[The Real Doctor]

Around two decades ago the engineering department of a Very Famous University decided to start electrical safety testing. They did this by buying one of the technicians a megger and telling him to go for it. He broke every computer and terminal he tried to test. Every. Single. One. In my research group we locked the doors and hid our equipment from him.

Another research group had an old valve radio which had at some point lost its case, but stayed in use nevertheless. The Health and Safety man visited, saw it, and silently cut off and removed the plug. Within five minutes of his departure it was back in use ... with bared ends of wires jammed in the socket.

Ian

[Andrew Gabriel]

I wrote the procedure for a former employer some years back. For things like desktop PC's, we basically never tested them. Brand-new undamaged stationary IT equipment supplied with a moulded-on mains plug was deemed to need testing every 4 years. We aimed to pension them off before the first test was due, as testing a 4 year old PC generally costs more than its worth at that point.

[PCPaul]

Dodgy supliers can be quite ingenious...

And as for wireless dongles...

[Andrew Gabriel]

Almost certainly due to using wrong type of electrical connection to an aluminium case. Was quite a common problem when PAT testing first came in.

The computer manufacturer I worked for in the '80's (GEC) had a few teething problems in this area when we starting using aluminium, having been pretty much exclusively steel up to that point.

This was brought home to me when I was designing a circuit to switch mains using power mosfets. During the breadboarding stage, I just used a bulldog clip to temporarily clamp the first mosfet onto a heatsink, and made a mental note not to touch the live heatsink. The next part of the breadboarding required a second mosfet, so I clamped that onto the same heatsink. Anyway, circuit all worked fine, so finally I disassembled the breadboard version to make the final version (which would of course have proper insulating kits between the mosfets and the heatsink). Only then did it suddenly dawn on me that the two mosfets had full 240V mains between their heatsink tabs. The only reason the whole thing hadn'd gone bang was the thin hard layer of aluminium oxide insulator which naturally and quickly forms over the surface of aluminium.

[Huge]

had to get rid of that nasty "chemistry" word.

[Andrew Gabriel]

PIN number...

Some things really aren't worth worrying about.

[Andrew Gabriel]

If anyone does insulation tests on a computer (or IT equipment in general) without first checking that the piece of equipment is designed to handle it (most aren't), they would be expected to pay for replacement due to being incompetent at PAT testing and consequently damaging the equipment. Note that such testing may also significantly reduce the life of such equipment even when it doesn't instantly destroy it. Such equipment should be tested by means of a leakage test whilst operating.

I would have said that was OK providing the adaptor is fused. When I was a student and a member of the Hall committee, I used to buy in bulk some commonly required adaptors of suitable quality and sell them at cost so people had easy/cheap access to the right things. In your case, you might do better to get some different cordsets with the 3 commonly used IEC inlet connectors (although some laptops are proprietry inlet connectors).