Portable Appliance Testing

Philip Jeffs
Member - 287 posts

How much 'damage' is allowable? How hot does a cable need to be to constitute overheating?

Very subjective questions and one wrong answer could lead to an electric shock for the user. You are still liable (as a company) for perhaps failing to carry out 'a suitable and sufficient' risk assessment.

In general this work should be carried out by someone experienced in what they are looking at, and with a degree of suitable training.

Don't suppose you are in East Anglia Ian?

Bill Scholes - Workplace Law Network
Online advisor - 15 posts

It is good practice for all users to be aware of the regular basic visual checks that can be carried out on electrical equipment that they use, however this should not be confused with the formal visual inspections mentioned in the HSE Guidance. Such formal inspections may require that covers are taken off equipment, plugs are opened etc. and therefore should be carried out by a ?competent? person within the requirements of the Electricity at Work Regulations 1989. This does not have to be a qualified electrician, but it should at the very least be person who has sufficient knowledge, training and experience to identify problems.

With a view to the checklist, it is unlikely that all of the questions could be answered without some dismantling of equipment and I would advise that it is probably better to invest in training maintenance personnel than to trust in any assumed competences of users.

For further info see HSE publications: IND(G)236 Maintaining portable electrical equipment in offices and other low risk environments (available free at www.hse.gov.uk/pubns/indg236.pdf ) or HSG107 Maintaining portable and transportable electrical equipment (available from www.hsebooks.com

Ian Pinder
Member - 1 post

I have a client who has working shops with tills/computer equipment etc. Apart from the normal items, Kettles, Fridges, Fans etc to take out the computer equipment to run a test on it seriously cripples the shops working capability. The Computers are constantly being updated from a central source in the UK and can take up to 6 hours to return to operation if they have been turned off. Out of hours working is not a practical solution. So therefore, A good visual inspection is the only way to proceed with these items. If we clearly stated the items visually inspected only, how does my company stand legally?

Anne Sherman
Member - 4 posts

I am due to sit the PAT testing exam on Friday 10th Feb. I have no electrical background,and am having a few problems with understanding the results of the tests (failures or changes to the original test results). Is there a web site that you can recommend that may be able to offer some guidance on this?

Anonymous

Do PAT testing labels have a legal
requirement ie does it have to have a specific re test date in the form of day-month-year.

Philip Jeffs
Member - 287 posts

Ian, the issue depends on how competent the person doing the inspection is. You refer to 'a client' so I'm assuming you are the contractor providing the service? In which case you work on your clients instructions that the servers etc are on a visual inspection only, and you provide a suitable disclaimer to identify the pitfalls in that approach, but it doesn't stop your liability as the contracted supplier to do the job properly, and with staff who know what to look for.


Anne, sorry I didn't see this prior to your exam. I hope you passed OK?

Anon, the label specifies a recommended retest date as the regs do not state any legal timescale. The item must always be in proper working condition, and you must always (as an employer) ensure that is the case. Clearly PAT testing is the usual means to do that, and annual checks are the most common, but frequently used items or those in severe environments like building sites etc would need inspecting more often. The comparison could be between a bedside lamp in a hotel that never gets moved from the same room and never unplugged, to an electric drill used daily by a builder?

Anne Sherman
Member - 4 posts

Failed the exam. Had a pass mark over over 76% for each section but still failed overall. C&G will not tell me why or what the pass mark is. Also one question had two correct answers but you could only choose one. No comment for C&Gs. Beware online exams!

Philip Jeffs
Member - 287 posts

C&G work on the basis of establishing a pass mark (for PAT testing anyway) based on all the exam results on that day. It therefore changes and isn't a set mark you have to acheive.

A bright student taking an exam on a day when there are a lot of lower marks will do well as the average pass mark will be low, whereas a lot of bright students all on the same day will raise the overall pass mark.

Anne Sherman
Member - 4 posts

That is so unfair. It means that you do not have an equal chance to pass. I will have a word with QCA about this!

Anonymous

hi i just failed my pat test and im wondering the software you use on the test is it avalible to buy like the driving theory test you can buy as a mock test if anyone could help please do has i have a retest in 1 week thanx,,,bill

Anne Sherman
Member - 4 posts

Thought you might be interested in the reply I received from QCA after they investigated my complaint about the test.

"I now have the following reply from City & Guilds

'At the end of each online test there is a breakdown of the examination. This is a visual guide to show how well a candidate has performed. The percentages on each section refer to how well the candidate has performed for each section.
It is important to remember that not every section is weighted the same. Please refer to the test specification within the scheme handbook for section (outcome) weightings.

It is not advisable to total the percentages for each section and then divide by the number of sections to find the candidate's result. This will give a false result.

The result is calculated by the mark allocation per section and each section is weighted differently.'

I am informed that each test does have a set pass mark so it does not vary with the quality of candidates but it can vary between tests. I have asked City & Guilds to review both the way they communicate with candidates and their policy on not releasing pass mark details.

City & Guilds will also look at the quality of the questions in view of your comments."

Judging by what else was said it looks as if I failed by 4%. The pass mark for my test was 80%.

Hope this helps othre people out there.

Anne

Nic Bowker
Member - 1 post

I wonder if you can help me.

I'm trying to do the PAT testing in our office and have a number of Dell monitors to test. There is an exposed metal plate on the underside of the monitors, and the labelling shows no signs of class 2 symbols.

I've tried phoning Dell to ask them but they barely understand the Queens English let alone what a "PAT Test" is.

I know that "if in doubt tests as Class 1" but we're getting a lot of high readings for equipment that is less than two to three years old.

Any advice?

Martin Pickering
Member - 4 posts

Dell should understand Portable Appliance Test.
High reading for what? If it fails, it fails.

I don't know if this is any help but via Google I found a PAT Testing DVD here: http://www.pat-services.co.uk/default.asp?prodidsingle=248

(I'm not affiliated, not on commission, no connection with this company).

Anonymous

Yes. Dell. God bless em.

26 minutes later on the phone, I ended up having to explain to them what class one and class two meant.

They've eventually replied with the following:

"The basic electrical classification of class is based on the operating voltages.

Class 00 - upto 500 volts
Class 0 - upto 1000 volts
Class 1 - upto 7500 volts
Class 2 - upto 17,000 volts
Class 3 - upto 26,500 volts
Class 4 - upto 36,000 volts

Our monitor operating range is only 230v input. I would say it falls under class 00 or class 0."

Makes you wonder doesn't it? Thanks for the advice though.

Anonymous

Hi all, I have a Seaward Supernova Plus tester, and need to use the enclosed software - which is PATSLite, however the disc has gone missing in a premises move, and I can't find anywhere to download this software. It's advertised as "free", but incredibly difficult to find!

Any ideas on where I would be able to obtain a copy fairly quickly?

Thanks

Jay

Jason Key
Member - 9 posts

who legally owns a fridge following the collection by council from domestic appliances. Council or person who it came from.

Is it legal to put the item into a government building then for use without being tested of its in correct working order and without being pat tested.

Wesley Anderson
Member - 3 posts

Monitors are always earthed but somtimes the casing makes it hard to get an earth. If you can get an earth then you should run the test for a Class 1 appliance.

(Please note this does not constitute advice and should be used at your own risk. Please refer to the IET Code of Practice or your PAT Testing equipment supplier for more detailed information).

--------
London PAT Testing
http://www.londonpattesting.co.uk

Andy Begg
Member - 2 posts

I don't suppose anyone out there has a specification for PAT Testing? As a government body we have to go out to tender for services but we can't find a spec anywhere?

Any suggestions?

Many thanks

Anonymous

Hi ,
Does anybody know if there is a list for seaward europa pat tester on what appliance falls into what catergory, i have just started testing and its a nightmare trying to figure out what appliance goes with what sequence

vincent maguire
Member - 1 post

Hi
Just like anon 21 sep 07 i am finding it really difficult to find out what test suits each item or appliance. If there is a list for the europa plus would it vbe possible to send a copy to me.

Gordon Barker
Member - 5 posts

Interesting reading some of the problems people are having over PAT testing.Having read the leaflet from the HSE I would not take to much of there advice to heart.Last week I was testing a solicitors office and the main failure I found during this inspection was a UPS with a badly cracked case,this was probably caused by the cleaners being hard with the vacuum cleaner.When I went to the store cupboard to check the server there was about 6 with same problem.New equipment rarely gets tested and just before last Xmas I was asked to PAT some fairy lights at a nursing home,all still in the boxes and carriers bags from the shop.First one out of bag went to plug in and low and behold would not plug into tester,had looked at plug as taken out of package but did not notice one pin slightly off line,open up plug to find that the wiring had been trapped allowing
pin to go out of line,remake plug wiring.So this was brand new and would not normally be tested and made in China so that poses a question.Another case,local hotel reception lead surge protected went to unplug from wall and trace back under desk,did not take out of wall as could hear a crackling sound,asked owner if any problems with computer at desk,no,went to collect tester and as walked back more sounds from desk area,large bang,hotel in darkness.The cause was the oak desk had been dropped onto the lead,fine before I moved it,it was hanging on by a thread inside and the area around was hot.Labelling is another cause of confusion,hand drier on fused spur,first one took cover off spur to find an earth wire so class I,next one same make cover off spur earth wire to drier,fine class 1,but this time no little screw head to get earth from,cover off drier and guess what label inside with class 2 emblem,earth wire had been taken through but of course not connected.There was no labels on the outside of this or the next drier to say what class or any other detail.You now ask why PAT this,client asked by there Health & Safety inspector,and hard wired items rarely get tested and could be advisable to do in a lot of cases.PC monitors often Class 1 but no access to earth point also a lot are now run from a class 1 transformer,you can only do an insulation test and maybe a leakage test on these,another item has this problem fans a large amount of these are class 1 but fully enclosed.Just as a point if you can run an earth on these items suggest you do not do it on a 25amp test,do on a 200mA test or lower,otherwise you could damage the circuits,you may get high readings though as the current is so small and you don't want to pay for a new one.Access to plugs,I was told that if you cannot get to the plug to be able to switch items off this could be be a fail, a common situation in most offices,along with the files dropped on cables.So I hope you may find some of this useful and there are lots of other points I could mention.Gordon Barker.TEE Ltd As I write this a local pub has just been gutted by fire probably caused by an electrical fault and our County Council wants to drop the only two fire stations left with 24 hour cover to daytime only cover.After the Penhallow fire which was local it does make you wonder what next?

Graham Kenyon
Member - 26 posts

I'm worried by what I'm reading here.

Appliance Testing (if required to be carried out) should be conducted by Competent Persons.

The Spiel about "Class" = "Voltage" is unfortunately way off. Even if the poster is confusing "Protection Class" with "Overvoltage Category", the description for "Overvoltage Category" is still incorrect.

Class 0 appliances should (in general) never be used in the UK (there are some special circumstances in specially managed installations). This type of equipment has Basic Insulation only, and therefore in a normal ("earthed") electrical installation there would be no protection for a user in the event of a fault in the appliance.

Class I equipment relies on Basic Insulation + Earthing of metallic casings, so that a fuse blows if the insulation breaks down.

Class II has two layers of insulating material (one of which may be an air gap) - this is "Double Insulation", or a very thick piece of insulation that can support higher than normal voltages - "Reinforced Insulation".

Class III is where protection is from a lower ("normally safe") voltage from a suitable safety supply.

Equipment may contain more than one means of protection - e.g. a CRT monitor that may have earthed parts, as well as Class II parts - in this particular case, the manufacturer is not permitted to use the "Box in a Box" symbol, which applies where all protection is Class II.

Also interesting are lap-top Power Supplies, which whilst "Class II" (and have the "box in a box" symbol for shock protection) they DO have an earth connection for what electrical engineers call "functional reasons", which is connected to one of the d.c. output connector to the laptop. This is definitely a MUST for relevant machines, if they are to be connected to a wired network or other machines such as serial/parallel printers, or projectors.


Having got that off the old chest.

Testing Class II and Class III equipment is often not necessary in office environments, and can cause damage, especially if "Flash" tests are applied. This equipment should definitely undergo visual inspection and checking of plugs.

Testing Class I equipment regularly is definately required, because if the earth connection breaks, as well as being dangerous, it's a direct breach of a "must do" regulation in the Electricity at Work Regs. 1989.

The IEE Code of Practice for In-Service Inspection of Electrical Equipment is the current UK industry best-practice guidance for PAT-testing.

EurIng G Kenyon
(Chartered Electrical Engineer).

Martin Pickering
Member - 4 posts

Thanks, Graham. A very lucid explanation, spoilt only by the misspelling of "definitely"! ;-)

It strikes me that a lot of people are carrying out safety testing without knowing what the heck they are doing (or why).

Stuart Todd
Member - 1 post

Hello,

For a detailed website about Pat Testing. Visit http://www.pat-testing-uk.info - its a free Pat Testing Information website.

Hopefully it can answer any questions you may have.

Gordon Barker
Member - 5 posts

Sorry that last time it would seem my thoughts were put down rather quickly as I was trying to do other work at the same time. Stuart is right when he mentions the web site for PAT,if you go into it have a look at manufacturers recalls,this is the new equipment that doesn't need testing??

In answer to Graham I thought that most of the laptop and monitor transformers I have come across have been CLASS 1,but without any external earth point,they are certainly not CLASS 2.Likewise if you read my first post I have said that no item that you suspect is delicate should be treated as just a CLASS 1 and tested at 25amps,this should be 200mA or less.

Flash testing should from my test meter manufacturer not be required only in circumstances such as after the repair of hand tools or similar,and when I used to run a hire company we used to have to flash test all our equipment when it came in from hire,that could mean 2 Flash tests per day at 3000volts!!What effect was this having on the insulation?

It seems strange to me this non requirement to test office equipment,as I pointed out this is often abused.Ask your insurance company about this as you may find this is part of your policy on the Health & Safety cover side of it.

Happy Testing and watch those knees.

Gordon Barker

Julian Davis
Member - 25 posts

Be careful of guidance from companies that also PAT test as it is obviously in their interest to get you to have testing. The authority as far I'm concerned is HSE's freely downloadable guidance indg236.

One of the first things you will note that it says ""The law requires it to be maintained. It does not require an elaborate and frequent system of electrical testing."

Further into the booklet you will note some combined testing and inspection tables. If you look carefully HSE stress they are 'initial' recommendations and from my point of view after several cycles of testing and very few failures I have moved our people onto a longer test regime based on the risk level of the equipment and the results of almost no failures. I still insist that operators regularly inspect portable equipment and we do have a rigorous replacement scheme for defects - but what we don't have are annual gravy trains for external contractors unneccesarily testing everything in sight and charging us a lot of money for doing so.

Graham Kenyon
Member - 26 posts

Gordon,

Quick note on Laptop and Monitor Switched-Mode PSUs. Most of these are not "proper Class I", because the earth connection is only used to connect the d.c. side (not mains side), meaning its primary function is "functional" rather than "shock protection" (as per Class I earth). Consider the methods of protection against shock in these devices - plastic cases and air gaps etc., just like a mobile phone charger.
However, as I stated, it's important to check this connection regularly, whether or not the switched-mode PSU has the "box in a box" symbol on it.

Julian,

When I used to repair appliances many years ago, the experience was that Class I fully-portable equipment (and extension leads used for hand-held or fully portable equipment) were most at risk of broken earth connection. These, along with equipment used in "rough handling" or "contaminating" environment (e.g. construction site tools and leads), are a must for very frequent inspection and testing.

Frequency for other equipment on a risk assessment basis as you identify.

It's worth noting that some of the problems with Class I portable equipment can be (should be) addressed at the procurement stage. For example, don't buy a Class I vacuum cleaner for general use in an office environment, unless you've a good reason to (there are good reasons for certain applications). The safety standard for domestic vacuum cleaners states that the machine must be Class II - this is not the case where the machine is intended for commercial or industrial use, so you have the choice (because of the special applications that require earthed vacuum cleaners). There are many good commercial/industrial Class II vacuum cleaners, even with metal casings !

JOHN WRIGHT
Member - 1 post

I have introduced a system for PAT every 2 years. Any new equipment purshased within this frequency has a sticked placed on it showing the date of purchase, the appliance is then (PAT) tested the next time all the other appliances are done.
As an ex Electrical Supervisor and now a H&S manager, I have trained our staff on "Visual Electrical Appliance Inspections" covering pretty much the same as what has previously been mentioned. There are tell tale signs with appliances and flexes before a fault occurs, such as a nasty fishy smell, usually caused by a loose connection creating heat resulting in the insulation (plughead/socket) becoming hot. Hope this is of use.
John Wright

Bernard Gale
Member - 1 post

Whilst the supplier would be liable its still good practise to test all new equipment coming onto site we recently bought four drills from a well know DIY chain all failed a PAT test. The insulation internally had been damaged in shipping.
We also encountered the same with a new computer and we were subject to a manufactures recall about power supplies which we had already picked up from PAT testing the item so I am not convinced the HSE are offering good advice!!!

Julian Davis
Member - 25 posts

To a certain extent I would agree with Graham reply to me but most of our kettles are cordless and never get unplugged and if they do show signs of wearing we would replace it as a kettle costs less than £20 and the cost of dragging PAT testers around the country inspecting our appliances are a damned sight more than that. The most imprtant aspect os managing portable electrical equipment is inspection by the user as and when they use it and replacing anything that shows signs of wearing.

david gwynn
Member - 1 post

Hi, I work in a school as an IT technician, the school caretaker has just qualified as a pat tester. Unfortunately, when he tested the IT equipment in the suite, the only 3 dell monitors we have failed on the class 1 test earth leakge, and a pc failed earth leakge. I bought a replacement, it failed, took tester to shop, tested 6 brand new psus 5 failed 1 passed, but that one was not for a normal pc. went to maplins tested 2, second 1 passed. Caretaker has now decided all new items are tested before first use. We have just bought 2 servers that sit in a locked cupboard can they be damaged by testing?
dave

Neil Britton
Member - 1 post

Hi

Can anyone assist

I am currently studying PAT testing using a DVD course I purchased, although it seems comprehensive it does not really cover off IT equipment much which will form a large part of my work.

My PAT tester has the 100mA option for the earth bond test which I understand, however I have the option to set the earth fault level to either .01 ohm and 0.5 ohm

Under what circumstances to I change the above options, is it safe to perform insulation tests on computers and should an earth leakage test be completed / if so what are the allowed levels for a pass

Graham Kenyon
Member - 26 posts

Neil,

IT equipment is the most difficult area, and the answer to the questions you've asked is, I'm afraid, "It depends". But there are a few things to note:

1. With a 100 mA test, the IEE Code of Practice recommends wiggling the mains flex at the plugs and socket / case entry, because this test can't detect broken earth wires as well as a higher current test. The problem with higher current tests and IT equipment (and some other electronic equipment) is that the earth to the case may come through the PCB - or there may be a parallel path (e.g. formed by the d-shell sockets on the rear of the computer), meaning the higher currents can damage the PCB.
So, if in doubt, either consult the manufacturer, or use the 100 mA test, wiggling the lead as recommended.

2. The IEE Code of Practice provides guidance on the allowable pass-rate, which depends on whether there's a detachable supply cord, and the length of the cord. (Section 15.4 - page 42 of my copy).

3. "Earth Leakage" - if this is measured at supply voltage when IT equipment is in use, the maximum allowable "leakage" for an IT appliance with a UK plug or IEC320 plug is normally 3.5 mA (as per the safety standard BS EN60950-1). However, higher values are allowed for certain circumstances - either "direct wired" or with an EN60309 industrial ("Commando") plug. Most PCs would be < 1 mA, although this is only a guideline - the standard allows more as I said.

4. It should always be "safe" (if the appliance is safe) to perform a 500 V d.c. insulation resistance test on Class I IT equipment, provided the equipment has been manufactured and production-line tested to BS EN standards, and the test is between "coupled current carrying pair" (CCP)and "appliance earth".

But some manufacturers don't recommend it - I'd be wary about this, because the standard production-line test for Class I should be at 1500 V a.c. (or 2100 V d.c.) between CCP and earth (again mandated by EN standard BS EN50116 - which should be used from 2006 on).

Graham Kenyon
Member - 26 posts

Quote:
------------------------------------
To a certain extent I would agree with Graham reply to me but most of our kettles are cordless and never get unplugged and if they do show signs of wearing we would replace it as a kettle costs less than £20 and the cost of dragging PAT testers around the country inspecting our appliances are a damned sight more than that. The most imprtant aspect os managing portable electrical equipment is inspection by the user as and when they use it and replacing anything that shows signs of wearing.
-----------------------------------

Whilst I wouldn't disagree that a testing regime needs to be sensible, it's worth thinking on this one.

Our recently-retired kettle at home (well known brand - but they're all realtively inexpensive these days) was metal-cased, with a tubular element attached to the underside of the water container, about 16 months old. It was therefore Class I earthed. Recently, I got home to be asked by my wife to have a look because she could hear a rattling noise when she picked it up.

The noise was due to a loose screw. However, a further two screws were loose. These three screws ensure that the earth is taken from the connector to the case of the kettle - so the appliance was not adequately earthed. In fact, the loose one was the one bearing the "earth symbol" for the appliance. The screws would have loosened because of

My point - for some time, the kettle was not adequately earthed (at work, this would be a breach of an absolute duty in Electricity at Work Regs). We had no way of knowing this without inspection and testing - although even if tested at 12 months old there would have been a period where the appliance was not adequately earthed.

Worse, if the element had become faulty, the kettle could have been a death-trap. The fuse would not have operated, and an RCD would only have operated on contact with a person (hence only reducing, not eliminating, risk of dangerous shock).


The conclusion I draw from this, is that at least PAT-testing, or a 12-month replacement programme, would have caught the problem and could have prevented an accident.

But you have to apply this with common-sense. FOr example, whilst this is good practice for CLass I (earthed) devices, it's not necessarily the case for phone chargers, for example, where user-inspection for damaged product would likely be more than adequate for most circumstances.

Common sense and horses for courses - as usual - should be applied.

Gordon Barker
Member - 5 posts

The forum seems to have gone very quiet,so just to reopen the debate this may be of interest.
In Bude a few weeks ago a hairdressers burnt down also I believe affecting other property,and just today I have heard that the investigation has concluded that the fire was started by one of the appliances in the hairdressers.Electrical faults are the second biggest cause of fires,the main one being arson.Food for thought??

Graham Kenyon
Member - 26 posts

QUOTE "Electrical faults are the second biggest cause of fires,the main one being arson"

This statement seems sort of "obvious". Even if we drive down the number of fires to a minimum, it may well continue to be the case, because electricity is a source of energy that's "always on" until the protective device (fuse, circuit breaker or RCD) operates.

RCDs don't protect against short-circuits between current-carrying conductors, only where a current-carrying conductor shorts to "earth" (either in the appliance, or through materials or people).

And if fuses and circuit breakers only let through enough energy so that a fire could not start, you'd not have enough power available.

Add that to the fact that now with the cessation of smoking in enclosed areas, In most workplaces, there aren't many other sources of ignition that are spread throughout the building (e.g. flames localised in a gas appliance) - and you can't see or smell electricity until something is going wrong !


This leaves us with a "what's reasonably practicable" situation I suppose. In other words, define what level of inspection and testing is "reasonably practicable" for your particular premises, using the guidelines in the IEE Code of Practice for In-Service Inspection of Electrical Equipment (for appliances and fixed equipment), and IEE Guidance Note 3 "Inspection and Testing", for the electrical installation itself (which can also be a fire hazard if faults are not noticed).

Pauline Dunlop
Member - 1 post

My Hubby has just started a course for PAT at the local college. They had a couple of sample test papers for him to get an idea of how questions are phrased. Does anyone know of a site where we could get some more?
Thanks
Pauline

S LEVERINGTON
Member - 1 post

Hello Pauline,
Ive just been looking for exactly the same as you have with regard to sample test papers for the PAT test for our maintenance guy, and have found a website
where you can download just that .
Its www.electacourse.com It does cost but hope its of use !!!

Phil Riley
Member - 4 posts

I recently did the C & G PAT testing course at the local college. I then started looking at setting up to do this work on a contract basis. I was a bit gobsmacked when I discovered how expensive the equipment has become. I ended up getting a secondhand instrument on Ebay for £185. I then bought a supply of pass and fail lables plus software for producing the paperwork. Of my 3 purchases, only the labels have turned out to be fit for their purpose! The PAT tester, a Seaward Primetest 100, is incapable of doing testing in accordance with the IEE Code of Practice. This is because there is no facility to disable the insulation resistance part of the test sequence. For most items of IT equipment the 500 volt insulation test should not be carried out as it can damage the appliance.
The software package contains the equipment register forms but does not include the most important form, denoted Vb in the IEE book. This is the form you complete for each appliance and use to record the test results each time you test that appliance. Having all the test results for an item together on one form means you can tell at a glance if the results are deteriorating over time. This can prevent the equipment eventually becoming dangerous if such deterioration is investigated before the results actually reach fail levels.

Graham Kenyon
Member - 26 posts

QUOTE "For most items of IT equipment the 500 volt insulation test should not be carried out as it can damage the appliance."

Is this really the case ?

Certainly, the 8A or 25A a.c. test for earth continuity may damage IT equipment (These tests can blow PCB tracks if the current happens to flow down a parallel path, depending on where you attach the earth probe or clip - perform the test at 100 mA a.c. or 200 mA d.c. if you are unsure, but move the lead as recommended in the IEE CoP).

But a 500 V d.c. insulation resistance test between ccp and earth (ccp is "coupled current-carrying pair", i.e. L&N connected together) should not normally damage IT equipment. According to the BS EN50116 standard, which is for routine production-line testing of IT equipment to BS EN60950, all IT equipment should be tested like this on the production line, but at a much higher voltage (typically 1500 V a.c. for 1 second for Class I components). Sub-assemblies may be tested separately.
The 500 V d.c. test should not stress the components in the IT equipment - but an a.c. test would, which is why the time is reduced to 1 s from 60 s between production-line test and the original type test.



Of course, the guidance must always be to only conduct tests that you are sure won't damage equipment - so don't do it if you are not sure yourself !

Phil Riley
Member - 4 posts

I don't have access to lots of IT equipment to check but none of the items I have looked at carry the BS EN 60950 markings so I could not risk testing them at 500 volts (See IEE Code of Practice page 44 note (3).

Graham Kenyon
Member - 26 posts

But if the appliances don't conform to BS EN60950, they must afford an equivalent level of safety. Surely, because BS EN50116 is the EU standard for production-line testing, then that must be used as the benchmark test to see if the appliance does afford that equivalent level of safety ?

This is a personal choice, but unless there are very exceptional circumstances, I do not accept equipment that can't withstand that test, because I don't believe that it affords equivalent safety to the EU standards, in which case how do I know the appliance is safe ?


There are some unusual exceptions, but in general if it's got a UK plug and is earthed, 500 V d.c. test ccp to earth should not damage the equipment.

Again, though, warning that you should only do tests if you are sure of what you are doing.

I'd ask, though, if you can't do the 500 V d.c. test for a Class I appliance, have you really achieved much in doing your inspection and test ?

And certainly if you miss out the earth continuity test, this is not adequate at all.


Back on insulation resistance, the appliance will be subject to "transients" well above 500 V on a regular basis (pluggable IT equipment needs to meet Overvoltage Category CAT II to be safe in the EU).

Again, this may put the user at danger.

So, whilst I understand the guidance, my knowledge and experience leads me:

1. to investigate conformance during inspection.

2. make a judgement and either FAIL or Test - and FAIL if the appliance fails the test.

But this needs the relevant knowledge and experience.

Simon Tisma
Member - 1 post

How many people out there would trust a member of there office staff to MOT their car?.
Having been involved with PAT testing for many years now I am still amazed at how many people pass the City & Guilds and still dont have a clue what they are looking for. I am sure when a member of staff takes up one of the many No Win No Fee available to them after even the smallest shock, the judge will say " its ok sir you thought you knew what was classed as safe".

Last year as a company, we performed 220,000 pat tests, we recorded nearly 18000 fails, of these 11,000 were basic visual failures such as damaged flex, the type the operator should have spotted, but could not be bothered and left it to "someone else" to report. These included the match sticks in the earth terminal, blue tack used as insulating tape, the famous Benson & Hedges 45 amp plug top fuse etc, . How many FM managers would let joe bloggs with his DIY skills perform the Fixed wiring test, not many, but the potential for serious injuries or fire is even more risky in movable equipment with exposed wiring.

Please, I may work in the field, i am not after work from anyone but it makes my blood boil over how many experts there are in this field, and before they all throw their arms up in the air, yes i am an electrician, yes i have passed the C&G laughable exam, yes i do have £15 million liability insurance, yes i do have £25 million Contracted works insurance, and yes i do have the experience to perform the correct type of test leaving my clients safe in the knowledge they have complied with the relavent acts and guidlines.

There are cowboy companies out there who will "bluff" the tests or make money for repairs that were not needed, but the majority of us carry out a professional service to a recognised standard. A job made harder by mis informed H&S or facilites Managers allowing people who have not a clue to do the work on the cheap. In fact if they were to consult their Insurance Companies they may find that in house testing is not favoured because of the risk of the testing not being performed correctly.

Sorry for the rant but please think before you act as YOU will be liable for any injuries and ignorance is no defence.

Phil Riley
Member - 4 posts

Simon, so just because I am starting this line of work in a modest way with limited outlay you assume I am some sort of cowboy, out to make a quick buck. You also seem to assume that I don't have public liability insurance. I suppose I could just carry on the testing, regardless of any risk to sensitive equipment, taking the attitude that the insurance will cover such eventualities. I have been in the appliance repair business for 10 years and have never had to claim on such insurance.
I have not started to offer the PAT testing service yet. I will not do so until I am certain that I have the right setup to do this work in a safe and professional manner.
I must admit, I only scored 29 out of 30 in the City & Guilds exam so I clearly don't know everything there is to know about the subject.

Phil Riley BSc

Graham Kenyon
Member - 26 posts

Phil,

Please understand it's my intention to help here and nothing else.

If you feel you need to understand more, you could get hold of the following standards (although they are a bit pricey):

- BS EN60335-1 (this is the basic standard for safety of domestic and similar appliances, but also is used for commercial cleaning equipment etc. Specific requirements for certain products are contained in additional standards B S EN60335-x - but bS EN60335-1 contains the basic safety requirements common to most appliances).

- BS EN60950-1 (standard for safety of IT equipment).

- BS1363-1 (standard for safety of UK plug, but also contains the table that determines cable size selection and fuse rating for the combinations acceptable under Plugs and Sockets Regs).

In addition, the following legislation is of interest:

- Electrical Equipment (Safety) Regulations (This implments the Low Voltage Directive in the UK, and is available to view/print freely from www.opsi.gov.uk).

- The Plugs and Sockets (Safety) Regulations (again, free to view/print from www.opsi.gov.uk).


There are also courses from organisations like ERA Technology, where you can learn about appliance construction for safety.


Whilst it could be argued that the above material is aimed at Designers, if you don't have prior experience of electrical and electronic equipment, and the EU legislative safety requirements and assiciated standards, you'd definitely benefit, especially if you are going to be a professional inspector, rather than work in-house on a limited set of equipment that you are familiar with.

Mike Maddison
Member - 2 posts

hello everyone.

I have just joined the forum and gratefull for some of the information listed. I am about to start a small part time business PAT testing . I did the C&G course a couple of years back along with domestic wiring instalation, 16th edition and inspecting and testing, as part of my ressetlement training when I left the RAF. I have just purchased a Europa Plus from an ebay seller which is away being calibrated at the moment. I have no problems with testing the run of the mill appliances, It's the IT equipment that I am still a bit unsure of so the info on the sight is useful to me. Looking forward to further info on the forum.

Ian Gardner
Member - 2 posts

Mike - I would strongly recommend that you get hold of the the new, 3rd edition of the IEE Code of Practice (it's got a purple cover).
A good study of this (most of which you should already know from the 2nd edition, having G&G 2377) should clear up any confusion regarding the inspection & testing of IT equipment.

Mike Maddison
Member - 2 posts

Just got my Europa Plus back from calibration ( ACUTEST only charged me £52.88 booking it online, that included shipping by courier both ways) and starting to familiarise myself with it by testing things in and around the home. Acouple of questions.

1. When testing a bedside lamp do you remove the bulb for the insulation test.

2. When testing an insect zapper do you remove the flourecent tubes and balasts as you would when testing a fixed intalation with flourecent lights.

Martin Pickering
Member - 4 posts

I can't answer your question (although my guess is "yes remove them") but I can help you to spell "fluorescent" and "installation" correctly. :)

Phil Riley
Member - 4 posts

With my tester you would not get a result if you removed the bulb as it gives a "Low Load" message. I would test a lamp with the bulb in and switched on. Similarly with a microwave oven you may need to have the door open so there is the load from the interior light to avoid this problem.

Graham Kenyon
Member - 26 posts

There should be no need to modify an appliance - including removal of bulbs etc., to conduct basic tests.

However, as always, guidance is as follows:

1. Don't do any tests about which you are unsure. (e.g. on inspect zapper, generally need the Earth Test which can be done without removal of the tube and ballast, but is the Insulation Test really that important ?).

2. Check specific issues that worry you with the manufacturer or the appropriate standard (if you know it).

Ian Gardner
Member - 2 posts

I would say that for a Class I appliance, once the earth bond has been proved, then some sort of Insulation test is important.
However, if a full 500V Insulation Resistance test is inappropriate, many PAT instruments offer alternatives, such as a 250V Insulation test, or a Protective Conductor/Touch Current test (IEE CoP section 15.6)