Could anyone use a PAT Tester?

📦-offer

#1

After our recent media coverage, someone locally contacted us to say that she was looking for a new home for her husband’s PAT testing kit. He has sadly died, and was thrillied to find somewhere that might be able to make use of it. It was last used in 2017, and it would probably be worth getting it calibrated. (We’d use it ourselves, but we recently raised funds with Waitrose Commuinty Matters and have bought one.)

Any takers?

Clare


#2

Great offer, Clare! If you could supply more information about the make/model, and perhaps a photo or two that might help :slight_smile:


#3

OK…so I believe it’s one of these: http://www.seaward.co.uk/downloads/PAT1000s-Manual.pdf
And here are some photos.


#4

I got an earlier model of the Seaward PAT Tester for the Cottenham Repair Cafe. The manual instructed the tester not to touch the tested item for 30 seconds after testing, as there was a possibility that the 500V insulation test could leave capacitors in the device under test charged! (This equally applies to your model.) I came to the reluctant conclusion that using the PAT tester INCREASED the risk of electric shock at a Repair Cafe! In my experience, insulation breakdown in an appliance that looks fine on a multimeter but faulty at 500V, whilst not impossible, is extremely rare.

I would refer anyone who insists on a PAT test to my article on the subject at http://www.evonet.com/evonet/index.asp?Page=34&ID=37.

As most houses now have RCDs to protect against electrocution (as do our Repair Cafes), there is a much greater likelihood of something we repair subsequently causing a fire. PAT testing is liable to give a false sense of security about this.


#5

If nobody else wants the tester, we’re trying to set up a tool library here that could make good use of it for stock checking. Wouldn’t be able to pick it up though, do you know how much it would cost to post, e.g. by myhermes or similar?

@Chris_Moller I agree to some extent, Portable Appliance Testing in its common application (with annual or biennial re-testing of appliances and machine calibrations) is a highly wasteful job-creating pyramid scheme giving a false sense of security.
However, when it comes to creating a planned preventative maintenance schedule, having more information about the wear on appliances does help. I would prefer that we replace or reform* PAT rather than discounting its safety value entirely. With its advised form not being a legal requirement for organisations, there should be more sensible application of it, e.g. with less of insulation testing for items that will not need it and more emphasis on the user inspections.
…and of course, less binning of “failed” things that can be mended with a new cable or similar, which is where we come in to teach that.

*(with a sledgehammer)


#6

@4ndy let me know a postcode that you’d want it sent to, and I’ll investigate costs. You can email it to me at repaircafeportsmouth@gmail.com if you’d prefer.
Clare


#7

Hi Chris

I don’t understand this sentence - please can you explain “much greater likelihood”? Greater than what? If the sentence is wrong/misleading/incomplete can you please edit to correct/elaborate preferably by editing your post? If you can revise so I better understand your intention then I’ll edit this post correspondingly.

I came to the reluctant conclusion that using the PAT tester INCREASED the risk of electric shock at a Repair Cafe!

Used without due care and attention, pretty much anything can be dangerous. Apparently many accidents requiring visits to A&E are a result of putting socks on or taking them off.

To be of any value, PAT testing (by which I mean the whole process of checking that mains-powered devices are relatively safe to use) must only be performed by what is termed a “competent” person - i.e. someone who knows what they’re doing, which among many other things includes knowing what the testing device does, how to use it safely (following its instruction manual) and how in general to proceeed safely when mains voltages are involved. I suppose one test of “competence” is whether the person could explain and justify their tests and results in court, should something with legal ramifications happen, and that the court would agree that those are acceptable, so it’s important to note that competence requires taking responsibility for the testing you do.

“Competence” must include discipline in following the instructions for the testing device being used. I use a Kewtech KT71 and the manual has many Caution boxes with instructions like “Do not touch the device under test whilst testing is in progress. Since a high voltage of 500V will be present the user may get an electrical shock” which seems like a pretty clear warning to me, so I try my hardest (it’s me that’s going to get the belt!) to avoid touching at all, or if I have to to hold the earth probe in contact then I avoid touching metal parts of the probe and the thing I’m testing, and to make sure no-one else stands a risk of touching it what I do prior to pushing the Start button is take a moment to stand back and check that there is nothing unintended touching the thing being tested and that there is no risk of anyone close by touching it - it’s good to have the PAT testing taking place in a little space of its own. If I have any doubt I don’t proceed. Mains voltages are dangerous. This sort of thing is also why the only people in the mending area should be those who have to be there because their stuff is being mended or they are in the repair cafe team, and why drinks/food aren’t allowed in the mending area, etc.

Also to put the 500V in context, mains voltage of 240V AC means there are peak voltages of +/-340V-ish (i.e, 680V peak to peak) when mains is connected - not that much different from 500V, so what would be the point of an earth leakage test at e.g. 1.5V or 9V from a multimeter when in real use these high voltages are routinely present? The likelihood of insulation breaking down increases with applied voltage.

We do all this because it’s generally acknowledged that devices which aren’t safety tested can be very dangerous, and importantly many of these risks are avoidable - that’s why PAT testing is often (usually? always?) a pre-requisite of liability insurance: it’s all about avoiding unnecessary risks.

Of course, devices that pass the PAT test can also be dangerous, because mains voltages are dangerous and users don’t necessarily understand what they’re playing with - but rather like our vehicle MOT tests the PAT test gives some basic assurance that the thing isn’t going to kill you or anyone else unless you the user do something slightly stupid or are unlucky.

In my experience, insulation breakdown in an appliance that looks fine on a multimeter but faulty at 500V, whilst not impossible, is extremely rare.

Yes it is very unlikely, but low probability (rareness) is not the same as impossibility or zero potential impact. Lightning does strike, and very occasionally it strikes multiple times. Aeroplane crashes are incredibly rare but I don’t want to be in one and in particular I don’t want to be in one where someone in the chain of command (and not on the plane) has blithely said “pffuh, bureaucratic nonsense that never happens [i.e. it hasn’t happened to us recently] so we don’t need to check it” when the event can in fact happen however unlikely and they could quite easily have checked it in order to avoid unnecessary risks.

If what you’re really saying is that casual non-“competent” use of a PAT testing device is potentially dangerous then I absolutely agree: yes it is, because mains voltages are involved! And that of course means you must make sure it is a “competent” person who takes responsibility for PAT testing. And then also please add that “casual”/“competent” qualifier to what you say and write because it’s important to qualify rather than making sweeping statements. So say instead “I reluctantly came to the conclusion that CASUALLY using a PAT tester INCREASED the risk of electrocution…” For me, that revised phrase really says “I reluctantly came to the conclusion that I wasn’t competent to do PAT testing” which I hope would then be followed by “so I found someone who is competent.”

Or if you have a truly compelling argument and evidence that a PAT testing device increases risks when used correctly in compliance with the instructions for that device by a competent person, then you really should make that argument to the regulatory authorities, or at least to the manufacturer of the device.

For me, performing PAT testing is a pre-requisite for liability insurance, and for helping to ensure electrical safety for mending volunteers - and this doesn’t absolve the volunteers from their responsibility in ensuring they repair safely and that the repair event proceeds safely.

Regards
Ian


#8

Hi Ian,

You raise some important and very valid points.

Danger of Fire vs. Electrocution

I find it relatively straightforward to repair and check out an appliance in such a way that I can be confident that it does not represent an electrocution hazard. I find it much harder to say that it won’t cause a fire. Here’s a little story that I may have told on the forum before.

A single mum with a baby in her arms brought a child’s nightlight in to the Repair Café to be repaired. The wiring was in a bad state, and we sorted that out for her - she was very grateful. As she walked away, I saw her take a 60W incandescent lamp out of her pocket and put it in. It was very lucky I happened to see this, as there was a label inside the nightlight that said ‘max 15W’. If I hadn’t spotted this, and a few days after the Repair Café her house had burnt down caused by the nightlight catching fire, I know I would have had some very difficult questions to answer!

It is common for us to get domestic equipment brought to a Repair Café that has been inexpertly repaired with something flammable, has insulated wiring touching high-wattage resistors, or has food buried somewhere inside, a toaster full of crumbs, or (as above) has had a lamp replaced with one that’s too powerful. I personally have had an almost new dishwasher catch fire (it was impossible for me to tell from the remains which component caused it), so evidently manufacturers find it difficult too. I’d be glad of a document I could give our Repairers that lists the things to check. I think the likelihood of an insurance claim against a Repair Café being because of a fire is higher than because of electrocution – but tell me if I’m wrong.

Competence of Repairers

There is a whole side discussion about the competence of Repairers, and what we do to validate this. It’s quite a sensitive subject, as the last thing a volunteer repairer wants is to be told he isn’t competent, when he thought he was. (Having said that, there are many Repairers who know that it’s impossible to know everything, and come to the Repair Café keen to learn new things.) Our current policy is that the first time, a new Repairer shadows an existing one, who is given the task and responsibility of establishing if the new Repairer knows the limits of his own knowledge. Is that precaution enough? (And if this is the policy from Day 1, how do you start?)

I’m very uncomfortable with “It’ll be safe if you follow the manual.” Everyone knows that the manual (if it hasn’t been lost) only gets read after something inexplicable happens. We know it shouldn’t be like that, but that’s human nature.

Hi-pot testing

Concerning 500V testing, an increasing number of products have Tranzorbs, capacitors or similar across the insulation barrier. These will indicate a fault at 500V – and might even be damaged by the test.

My central concern with PAT testing is that the most important part of the test is a visual inspection, and a rigorous application of common sense, but when you have a smart-looking testing machine to show off, there’s a danger that that gets forgotten!

Anyway, this is an important topic, and we do all need to be aware of our responsibility, and know the limits of our own competence.

Best wishes,

Chris


#9

If I were designing a machine to test insulation by applying 500V I’d ensure that it put a relatively low resistance leakage path between the test probe and ground as soon as the test completed, in order to discharge a suppressor capacitor if present. Do PAT testers not routinely do this? It would seem negligent not to. But advising the user to wait 30secs before touching the device doesn’t seem to make much engineering sense. If there is a discharge path then any charge should decay in a very few seconds or less, and if there really isn’t, it could remain for many minutes or even hours.

But at the same time it would seem negligent of an appliance manufacturer not to provide a discharge path for the suppressor capacitors (probably the normal path through a motor or PSU) as otherwise there could be over 300V between the live and neutral pins of the mains plug when you withdraw it from the socket!

In any case, the sort of shock you could get from a suppressor capacitor would hardly even compare to stubbing your toe. Though <shameless diversion>I had a school friend (now a university professor) who at one point was suffering bullying from a particularly unpleasant classmate. So one morning, before coming to school, he charged up a capacitor (much bigger than a suppressor capacitor) to a few hundred volts, with 2 wires running down his sleeve to his fingertips, and insulated from them with sellotape. Somehow (and I’ll never know how) he managed to get to school from the next town without discharging the capacitor through his fingers or through anything else. When said unpleasant individual turned up and (predictably) started giving my friend grief, he managed to apply the wires to their target. The result was that the bullying problem was instantly short circuited. Said individual never discovered what my friend had done to him, but evidently didn’t like it!</shameless diversion>


#10

Hi Clare, Not sure if this item was claimed, but if it is still available as a gift, We’d certainly be able to make use of it at Leicester Fixers, would need to figure out how best to get it here though. shame I didn’t see this earlier as I was in Brighton over last weekend.
Regards
Divya


#11

Sorry, Divya, but this is heading to Forres in Scotland next month…but will let you know if we ever get offered another.

Clare


archived #12