Pat testing equipment

[Simon]

My local repair café wants the ability to PAT test equipment and stuff we repair. There are various machines on the market that range from £150 to over £1'000. Are these all better and worse versions of the same thing or are there different requirements for different types of item?

[KevinA]

The AVO PAT101 was always my favourite. It does all the tests required, plus it has a low voltage power test, which tells you how much power the DUR would consume if it were connected to the mains.

[Simon]

Is that a megga one? from what I can tell a little out of production.

[themadhippy]

The basic pat is the same regardless of whats being tested,insulation resistance. and earth conductor continuity.How do you want to test,fully automatic or select which test to undertake ,do  you want the ability to scan a bar code to id the item under test ,store the results on the machine or export them,print out a pass/fail label,test 110v as well as 240v?
Do you want simple pass/fail indication or ,like me you prefer to see the test results .
One useful essential setting is a low current earth test,often called "IT " .

[Simon]

Well it's probably going to be used by people who do not use it all the time so automatic would be useful. Because they would be testing things to give back to people after repair some sort of record keeping is probably a good idea.

[Audiorepair]

Well it's probably going to be used by people who do not use it all the time so automatic would be useful. Because they would be testing things to give back to people after repair some sort of record keeping is probably a good idea.

The whole PAT testing world is a totally grey area.

Perhaps the only simple none grey fact in that world is that the PAT test has to be conducted by a "Competent person".

There is no real definition of a "competent person", you would have to argue that in court, should somebody die or be injured as a result of an incompetent PAT test.


So if you think 'that every Tom, Dick, or Harry can competently carry out a PAT test by pressing a couple of buttons, then I think you should consider very carefully your Public Liability Insurance at the very least.


In your situation, a data logging PAT tester would be IMHO a minimal requirement, so that when you get sued, you can at least show the data the test provided, and that it was competently carried out.

[Simon]

whoever does it will have been on the course. It probably won't be me as I am leaving the area.

[Audiorepair]

You can pick these up pretty cheap, and they will store and download data and you can customise all your tests into automatic programs.
This includes run under full power tests that the cheap equipment is not capable of.

https://www.ebay.co.uk/itm/115076808620?hash=item1acb1cbfac:g:iTcAAOSwlflhgZZb&amdata=enc%3AAQAHAAAAoIjrPvqvlyWOxacfniUXThMLg6ThW8uEQW7VAe%2FY6LvaizIHR8ZEastzQlyt8ZlKJv0pbcVKol3Pz5OKEbbZb0K2pNUNVb9Z1yhb6iprTawO1Z5OtErULJCzDVdq78mH6Xtd%2F1xdJvajvTf%2BP%2FruphLY%2BCXqBepy%2F8LCNrYeOiVZy7vnnNVcLnX%2BDQls84j%2BJZRDHPgj7heNNqI8bIHFYgQ%3D%7Ctkp%3ABk9SR67ajNTVYA


If you go down that route, have it calibrated first, then you will have a top notch machine you can rely on to keep people safe, and yourself out of litigation.

[themadhippy]

a data logging PAT tester would be IMHO a minimal requirement, so that when you get sued, you can at least show the data the test provided, and that it was competently carried out.

I'd disagree and suggest just have a book to log the results as its only going to be used for 1 off tests,if your testing   the same kit time after time then it maybe worth while

There is no real definition of a "competent person",

surely paying your money  and sitting through a day of  power point presentations before taking  an exam you can keep retaking  until you get enough correct answers to pass and being awarded a nice publisher made certificate is more than adequate

[nightfire]

Ok, here also my 2 (Euro)Cents ;-)

Forewarning: Here in germany regulations are a bit elaborated regarding PAT tests and the duties of a company of the need of regular testing. I myself have (besides being a sysadmin) the qualification of testing appliances, as my employer is a company that does consulting in this area as one of the main business topics...
(So I am being a "befähigte Person" according to TRBS 1203 and I do the inhouse PAT tests)- the requirements that those tests are to be done are mandated by insurance (Berufsgenossenschaft), so the standard there is actually calleed DGUV Vorschrift 3, the technical way HOW to conduct those tests are written in electrical standards (VDE), currently VDE 0701-0702, which has been recently split into VDE 0701 and 0702, respectively.
(DIN EN 50678 VDE 0701:2021-02 and DIN EN 50699 VDE 0702:2021–06)

I do NOT know how the legal stuff works in UK and what is mandated by local regulations, and how well a repair cafe fits in this, so I can only give some general tips and considerations for this.

First: It is a good thing that the people running the cafe care about safety, as sometimes some very questionable things can happen during a repair or simply do not get noticed. And if they (what nobody hopes for) come in a situation to explain to a judge why some repaired appliance killed or injured somebody, some solid paperwork is the only thing that helps explaining things.
Second: Knowledge WHAT to do is always required, and more important than a fancy tester. I also have seen lots of protocols where people conducting tests simply chose the very wrong steps to do.


This said, there can be multiple ways to conduct this. If they aim for having some serious proof that they did the correct thing, the devices should have a recent calibration, and some course how to do this is never wrong.
If they would have to give proof that they did some PAT test, a protocol is a MUST-Have. This can be manually written (here in germany there is something the ZVEH developed) as template, but they can make their own- some simple Excel sheet would be sufficient. Print it out, maybe manually fill in the measured values, and sign it. Important: The PAT tester(s) have to be included in the protocol with serial number, so that in case of trouble one can recreate the way everything has been measured. Also the device under repair has to be able to be clearly identified, like by model and serial number.

The tests itself are basically the same for the past 30+ years, only some slight adjustments in the tolerated measurements have been made, so basically it all boils down to:

- Check earthing of the touchable parts, if present. This has (in germany) to be conducted with a current of min. 0.2A and should yield a resistance <0.3 Ohms.
- Check isolation of all touchable parts, if not grounded. This should be done with 500VDC, and the tester has to limit the current (I think to about 1mA to protect the person doing this).
- Check isolation of L and N against PE, if present
- Active tests then involve firing up the device and measure the leakage current via PE, if present
- then the current at metallic parts that could be touched and are not grounded has to be measured

Thats the standard program, if there are other safety mechanisms present, like an embedded RCD in a hoover or similar, or some protection thermal switch in a water cooker, this also has to be tested if they function.

For ease of use, a PAT tester that can do all of it is nice, but it is totally legitimate to use different testing devices. This specifically applies if there is a low volume of appliances that are to be tested.
At work, where I do mostly the initial testing of new gear like freshly bought Notebooks (resp. their Power supplies) and desktops, or the freshly bought new coffee machine because the old broke down, I use an appliance tester that is controlled via USB from my Notebook and has an application on it that stores the measured values in a database and creates fancy protocols with it.
Especially in a corporate environment, where the same piece of hardware will get several tests over the course of its lifecycle, this is a big timesaver due to automation.
At home, where I do some tinkering and private repairs (I repair stuff that I will then use to repair other stuff...) I managed to get my hands on some old isolation tester about 40 years old, but perfectly working- Last calibration in 2015, and aside from a slightly damaged tip (which I will replace with a standard 4mm jack to put various standard probes on it) it is in perfectly working order.

With this isolation tester, I can test isolation with 500VDC (in reality it puts out 660VDC), and I can measure low resistances up to 4 Ohms with 0.2A current.
->For electric equipment like extension cords thats all.

Leakage currents are a bit more difficult to handle, especially when according to EN61010 some frequency-dependant characteristics of the current has to be taken into account. Here some leakage current clamps might be acquired for decent money that have the so called "50 Hertz filter", that dampens frequencies below and above 50 Hz to simulate the body sensitivity. With an adaptor, the Device under Test can be put on a wooden board for isolating it from the ground and then the PE leakage current can be measured via clamp- Touch current basically could be made the same way, as you connect the touchable conducting parts of a device (that are not grounded) to external PE and then measure the current.

Voltages from power supplies can be checked with a reliable multimeter.

Important: All of them should have calibration protocols and be noted in the PAT protocol.


If someone here could share some knowledge about the situation in UK, how PAT testing is done there, and which electrical standards apply?

[nightfire]

a data logging PAT tester would be IMHO a minimal requirement, so that when you get sued, you can at least show the data the test provided, and that it was competently carried out.

I'd disagree and suggest just have a book to log the results as its only going to be used for 1 off tests,if your testing   the same kit time after time then it maybe worth while

Here in germany you basically are free in which form you document the results. A template that is simply filled in with the required things is a valid protocol, that is then signed by the person conducting the test.
BUT: As there is no low regarding those in case of an accident ultimately the judge (or some appraiser) decide upon all the circumstances if they would accept this protocol as valid proof that at time of testing the appliance that caused an accident was completely ok...

Example: When holding the probe away from the appliance that gets tested, you get verrrry good results in the protocol- or someone tests leakage currents of a PC whilst using the so called "Ersatzableitstrommessung"-

And in the finer points: In my experience, there are lots of stuff even (or sometimes especially) are done wrong whilst using the automated or logging testers- simply because some half-knowledgeable person pushes some button, gets some green light and thinks everything is done.

[Simon]

ultimately unless you film the whole repair and testing it will always be opinion. I have already suggested hand in and hand back forms with details of work and photos.

[Zero999]

Most PAT is visual inspection. Many products can't be put on PAT equipment because they will be damaged by high currents and voltages.

Of course get a specialist piece of equipment, but it's not the most important thing. An ordinary insulation tester and low resistance meter will do.

[nightfire]

Do you have any examples of stuff that will break?
In my experience, the stuff that broke during testing was very old and already pre-damaged, and therefore would have posed some risk for further operations- and I myself have only permanently damaged some power cords with flaky PE.

Also, when it comes to power supplies of IT equipment like PC/Notebooks: EN 60950 and successors say clearly 500VDC is ok for them, that they have to survive this.
In german VDE 070x, there is also the passage that for this equipment, when in doubt, it is a valid option to reduce the testing voltage to 250VDC, or omit the isolation check if the person conducting the test can do other things to ensure the good state of the tested device. And this needs to be documented in the protocol, why a step has been left out.

[Audiorepair]

Many PAT testers have a "flash test" that will send more than 1kV to the device under test.
Just in case this happens in the real world, I guess.

But this may damage the device under test such that even though it has passed the test, it may now be damaged, and thus more dangerous than before, but now has a sticker telling you it is safe.


Also, I have been given equipment to repair that has been obviously been damaged by an incompetent PAT tester.

Typically a digital piano that is actually a Class 2 device, but someone has decided to attach the PAT tester's earth cable to a jack plug inserted into an audio output, as that is the only earth they can find.
The PAT tester then sends up to 60A down this jack plug, and through the PCB traces back to the mains inlet, and all the PCB traces disappear in a puff of smoke.


This is why PAT testing really does need to be carried out by a competent person.

[nightfire]

oookay, I see that we are talking about different types of PAT testing...

In my area and VDE based standards, the limits and normative stuff is as follows:

- proof of low resistance for the PE: 0.2A minimum, and the PE should be <0.3 Ohms Some testers have an option for 10A or 25A, that is useful with the contacts on water cookers and cable drums, that oxidize a bit.
- isolation test is done with 500VDC, and current limited to about 1 mA



There are some special testers around, that rather are used by the manufacturers to be used within a manufacturing line, to push higher isolation voltage checks- or give proof that the connections in a device really hold double the rated current of the plug.

But the "normal" stuff with PAT testers available to the ordinary guy conducting those tests usually should not have those options.
I personally work with several testers at my job, and one of our main PAT testers we use is the Metrel Omega/3360 line. Something like this would be a "normal" PAT tester for me.
(Yes, packed with features and on the upper part of the scale of PAT testers, and probably way oversized for a repair cafe)

[Audiorepair]

But the "normal" stuff with PAT testers available to the ordinary guy conducting those tests usually should not have those options.
I personally work with several testers at my job, and one of our main PAT testers we use is the Metrel Omega/3360 line. Something like this would be a "normal" PAT tester for me.
(Yes, packed with features and on the upper part of the scale of PAT testers, and probably way oversized for a repair cafe)

OK, I don't know what kind of equipment Repair Cafe's deal with, and I admit I assumed here they would come across the odd cooker, welder, 110v site equipment, stage lighting, valve amp etc.

So if they are going to incorporate PAT testing into their environment then they (IMHO) need to do it professionally and safely, and keep records, preferably recorded by the equipment, not on a paper pad.

I don't think buying a £199 tester on Amazon and have someone press a button and if there is a green light, stick on a PASS sticker, is really going to cut the mustard here.

[nightfire]

Fully agreed. Lets assume they mostly will deal with household items, like cookers, lighting, hoovers and coffee makers and also some computers, the testing itself is not that complicated if the person doing this has understood what has to be done and developed some routine.
I do not see a need for a top-of-the line PAT tester, but depending on the skills of the person using this, some lower end gear could be sufficient.
In my opinion, a tester has to provide:

- PE continuity check with 0.2 A
- isolation test with 500VDC
- active check for leakage currents, preferrably differential measurement
- touch current

and thats nearly it- better testers have some integrated storage for the results and some additional gizmos, like some simple software to get the data transferred to print some pretty protocols.

Most important (as always) is the skill of the person doing this.

Does anyone has some hint or link to applicable regulations in UK/the area where that cafe is located?

[Zero999]

If the device is going to be dismantled, then reassembled, a much more rigorous visual inspection can be performed, so whilst a tester is still required to meet the regulations, it's less important from a safety perspective, than not taking something apart. It's possible for something to pass the earth test, yet fail later, if the earth connection is poorly crimped and will just fall off. Dismantling and visually inspecting the insides would have likely revealed such a fault.

[themadhippy]

- active check for leakage currents, preferrably differential measurement
- touch current

Here in the uk those 2 are not a pat requirement,and being pedantic pat  was not meant for enuring mrs miggins toaster was safe after an element transplant.Pat was introduced to ensure portable electrical equipment was safe to use by employees,and apart from the visual inspection only requires an insulation resistance test,and if applicable an  earth continuity test ,the only other test is polarity if your testing extension leads.

[nightfire]

Yes, PAT testing also in germany was primarily intended to ensure work safety, but the same principles of testing apply to all devices and appliances after repair- and if some accident occurs, having some papertrail available is basically the only way of being able to get some bonus points in court...

OK: Lets assume that due to the legal situation after a repair only continuity of the PE/Grounding has to be checked, isolation tests have to be conducted, and polarity checks have to take place.
In this case some simple Isolation tester that also has a continuity range with 0.2 A would basically be sufficient and not break the bank.

Yes, some higher end model with automated logging etc. is capable of way more stuff, but it would be a big step in the right direction, including some handwritten protocols and some stickers to the tested devices including some serial numbers.
The Uni-T UT502A would essentially do this after a short look in the manual.

Again, I do not know about the normative situation in UK, here in germany this setup would only cover extension cords and similar stuff without electronics. Testing a PC would require here the measurement of leakage currents, otherwise the testing is not done to standards (VDE 070x) and therefore invalid.

[Audiorepair]

Yes, clearly there is a difference between PAT testing at the basic minimum required by law in an office, and PAT testing after a repair in a Repair Cafe, or making safe an industrial environment.

The Repair Cafe should surely be doing their utmost in making sure their repairs are safe, and at the same time could be seizing this opportunity to educate their community further on how to ensure those repairs are safe, and perhaps when it isn't by appropriate demonstrations with a PAT tester.

[nightfire]

Agreed. And to put some numbers in: Here in germany there are estimations that approx. 80% of faulty appliances/devices are detected by the visual inspection of the person doing those tests. Simply because some things are there that cannot be measured, and some loose screw that holds some PE connection does not immediately give bad values over the normative limit.

Also most other cases of serious issues that could hurt the user of some electrical device can be detected by strange isolation values.

At this point I have to state that the measurements have to be interpreted- in reality sadly lots of people like to go like: "Hey, I measured a PC and the PE conductivity, measuired to 0.25 Ohms is below the 0.3 Ohms that VDE 070x mandates- so the PC is good to go and I can proceed".
Usually including the power cord I would expect some value below 0.1 Ohms, so a value of 0.25 is way too high, and has to be checked.
Similar situation with isolation values. Limit is mostly around 1 or 2 MOhms, but cables and most other electronic parts (like Y capacitors) should give isolation values of way above 20 MOhms, which is end-of-scale for lots of PAT testers. If it is below, a competent person should also question the cause of this.

So it is important to begin somewhere, and even if at the beginning of doing those tests some slipups happen, it will be a big difference to doing nothing-  measuring also helps to sharpen the eye for potential zones of problems in the repaired units.