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Cruisin' Susan  
#1 Posted : 15 March 2010 10:15:24(UTC)
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Cruisin' Susan

Can anybody explain why computers are not PAT tested please? Are there any other items of equipment that should not be tested?
Rob35  
#2 Posted : 15 March 2010 10:21:44(UTC)
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Rob35

Originally Posted by: Cruisin' Go to Quoted Post
Can anybody explain why computers are not PAT tested please? Are there any other items of equipment that should not be tested?
My understanding is that it can damage the pc (Hard Drive), but they will check the lead as this is the item likely to be faulty / damaged. I am sure somebody will come back with a more technical answer ;-) Rob35
Canopener  
#3 Posted : 15 March 2010 10:53:34(UTC)
Rank: Super forum user
Canopener

First things first, do remember that while there is a requirement to maintain electrical kit in a safe condition, there is no specific requirement to TEST. Have a quick look at the guidance on the HSE website and ytou will see that the HSE do not recommend testing of class 2 kit - http://www.hse.gov.uk/pubns/indg236.pdf
RayRapp  
#4 Posted : 15 March 2010 11:26:54(UTC)
Rank: Super forum user
RayRapp

As a rule delicate electrical equipment such as computers are not PAT certificated. I have been told that there is specialist equipment available which will PAT certificate computers and not damage the internal gubbins. Mentioned already, but there is no legal requirement to PAT.
Hally  
#5 Posted : 15 March 2010 11:49:43(UTC)
Rank: Super forum user
Hally

As stated by Ray, you can obtain a tester that can also do computers. We have one for this purpose so that we can test everything.
firesafety101  
#6 Posted : 15 March 2010 11:51:07(UTC)
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firesafety101

Tigers  
#7 Posted : 15 March 2010 13:34:43(UTC)
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Tigers

PC's are not really portable if you need to transport a system you would normally use a lap top or hand held device.
safetyamateur  
#8 Posted : 15 March 2010 15:24:28(UTC)
Rank: Super forum user
safetyamateur

Pretty sure the rule of thumb with portable appliances is 'does it plug into a socket?'
Neil P  
#9 Posted : 15 March 2010 15:39:23(UTC)
Rank: Forum user
Neil P

Hi Susan, People were reluctant to PAT test computer equipment because early (and some current) testers could damage computer equipment due to the high current and voltage passed through the equipment by the tester during the tests. The latest PAT testers have built in programs that reduce the current and voltages passed through the equipment to avoid damage. PM me if you require a specific make and model (No connection with manufacturers). As mentioned earlier, there no legal requirement to PAT test but you must ensure that equipment is safe to use. You may find that your insurance company insists that your computers are PAT tested. This is something you may wish to check. Regards, Neil.
ahoskins  
#10 Posted : 15 March 2010 15:47:53(UTC)
Rank: Super forum user
ahoskins

The most recent guidance extends testing to almost anything connected to the fixed wiring through a flexible cord - even if connected via a spur outlet. We do test our computers, but not as often as equipment which might be prone to abuse/damage. I am not aware of any computers which have been damaged by this test for many years, but we certainly had a few fried ones in the early days...
mark.g  
#11 Posted : 15 March 2010 15:54:09(UTC)
Rank: Forum user
mark.g

As stated the legal requirement is to maintain not to PAT test. It is better to have a system of informal user checks before use ....is the plug wire/ damaged signs of burning etc suplimented with formal checks where the fuse etc is checked and a record kept. The HSE regonises that 95% of all problems can be detected this way. Dependent on history usage PAT should be considered for class 1 equipment. The latter two should be at a suitable period ....weekly and quarterly for equipment on construction sites ....bi annual and never for IT equipment in offices. A sensible well thought out scheme is far more effective, cheaper and safer than the typical 12monthly test of anything that plugs in. To answer the question PC are usually in office environments not subject to movements, low voltage (excluding the power pack), used by the same person and they can be damaged by some tests ...this equates to a low risk of damage occuring ....if damage does occur the risk of injury is remote .. any damage is likely to be detected by the user...Result testing is unlikely to achieve anything and may be detrimental
mark.g  
#12 Posted : 15 March 2010 16:02:15(UTC)
Rank: Forum user
mark.g

PS if any one wants to charge for testing phone chargers etc they are at best incompetent at worst ripping you off. A visual check of the plug is all that is required (a test wont achieve anything).
User is suspended until 03/02/2041 16:43:28(UTC) IanBlenkharn  
#13 Posted : 15 March 2010 17:02:59(UTC)
Rank: Forum user
IanBlenkharn

The all-embracing first push to comprehensive PAT testing occured when I was working at one of the UKs largest universities. Someone had the great idea that every item of plugged electrical equipment would be tested - forget teh cost - and there would be no exceptions! When the contractors were about half way through the task so many PCs and laptops had been fried the staff rebelled and the programme was abandoned
Grizzly  
#14 Posted : 15 March 2010 17:30:30(UTC)
Rank: Forum user
Grizzly

mark.g wrote:
PS if any one wants to charge for testing phone chargers etc they are at best incompetent at worst ripping you off. A visual check of the plug is all that is required (a test wont achieve anything).
Not so at all. Most phone chargers (& similar power pupply units) would be Class II appliances, and so a Class II insulation resistance test (after the visual inspection) would certainly be applicable. If you still think that is a rip-off, have a read of the research that the Electrical Safety Council & Trading Standards have been doing on sub-standard plug-in chargers: http://www.esc.org.uk/bu...y/research/chargers.html
rnighting  
#15 Posted : 15 March 2010 17:57:14(UTC)
Rank: New forum user
rnighting

As the inventor of the PAT Tester and the originator of the PAT testing activity and methodology over 20 years ago, perhaps I can reduce some of the myths and misunderstandings. There is no specific legal requirement to test. The legal requirement is contained within the Electricity At Work Regulations (Reg 2) (EAWR) that defines anything that can be attached to a fixed electrical system in any way as part of that system. Regulation 4 requires the maintenance of electrical systems to prevent danger, hence portable appliances that can be attached to the mains in any way must be maintained for safety. The reason that they are inspected and tested is to determine whether they require to be "maintained to prevent danger" at that time. With regard to PC testing, I have tested very many over the years and have never damaged any of them (or anything else for that matter). The potential problems with electronic equipments is that they contain many high impedance semiconductor junctions. When dielectric strength tests are undertaken (flash testing) the high voltage generated by the tester creates an electric field between the two test probes. If this field passes across any high impedance junction contained within a computer "chip" there is a high chance that such a junction will be permanently damaged (ie the chip will be "blown"). The required PAT tests are all based on tests that must be done by the equipment manufacturer after the equipment is built (as per the appropriate construction Standards); however, with regard to the flash test, the manufacturer is allowed to remove any component that might be damaged by the test. Clearly, during the later PAT testing by the user, this cannot be done. I therefore initially recommended that flash testing be omitted on electronic equipment. The response of PAT Tester manufacturers was to produce PAT test instruments specially for the IT scenario. Such PAT Testers were only "conventional" PAT Testers with the flash test removed so that no damage could be done. Unfortunately, such testers could not fully test electrical items that would not be damaged by the flash test. If anyone has any further questions I would be more than happy to answer them.
User is suspended until 03/02/2041 16:43:28(UTC) IanBlenkharn  
#16 Posted : 15 March 2010 19:22:02(UTC)
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IanBlenkharn

Fascinating. I suppose the obvious rejoinder is to ask why you didn't invent a test kit that the average PAT test gadgee can use effectively without causing damage to PCs? Seriously, I assume that theer is a variety of kit for different aplications and with inadquate training and limited experience damage will be done. What is the solution? A reputable contractor, better manuals with a high hope that someone actually reads them, failsafe equipment design [I presume its better now than at the time to which I referred], regular backups of PC data etc etc? It's all good stuff but if your PC has just been fried none of it offers solice and the business impact can be particularly severe.
Grizzly  
#17 Posted : 15 March 2010 20:16:22(UTC)
Rank: Forum user
Grizzly

rnighting wrote:
As the inventor of the PAT Tester and the originator of the PAT testing activity and methodology over 20 years ago, perhaps I can reduce some of the myths and misunderstandings.
I think that if you're going to make claims like that, we need a bit more than a forum username to go on!
Quote:
The required PAT tests are all based on tests that must be done by the equipment manufacturer after the equipment is built (as per the appropriate construction Standards); however, with regard to the flash test, the manufacturer is allowed to remove any component that might be damaged by the test. Clearly, during the later PAT testing by the user, this cannot be done. I therefore initially recommended that flash testing be omitted on electronic equipment. The response of PAT Tester manufacturers was to produce PAT test instruments specially for the IT scenario. Such PAT Testers were only "conventional" PAT Testers with the flash test removed so that no damage could be done. Unfortunately, such testers could not fully test electrical items that would not be damaged by the flash test.
I'm sorry, but the flash test has no part in in-service inspection & testing ('PAT'), for IT equipment or any other appliance. The testers that have tests designed for IT and other sensetive electronic equipment do not just have "the flash test removed" as you state, but rather have low-impact versions of the standard tests, such as low- rather than high-current earth bond test, and alternatives to the 500V insulation resistance test. So, not that I don't believe you, but...
mark.g  
#18 Posted : 16 March 2010 08:39:13(UTC)
Rank: Forum user
mark.g

mark.g wrote:PS if any one wants to charge for testing phone chargers etc they are at best incompetent at worst ripping you off. A visual check of the plug is all that is required (a test wont achieve anything). Not so at all. Most phone chargers (& similar power pupply units) would be Class II appliances, and so a Class II insulation resistance test (after the visual inspection) would certainly be applicable. If you still think that is a rip-off, have a read of the research that the Electrical Safety Council & Trading Standards have been doing on sub-standard plug-in chargers: http://www.esc.org.uk/bu...y/research/chargers.html A phone charger is typically either a voltage divider set up or combination of transformer diodes etc dependent on the power required. An insulation resisitance test between live and neutral would achieve nothing as the live and neutral are connected through the voltage divider / transformer.. There is no earth. The output is typically below 50 volt ac 110 volt dc (usually much less) which are classed as safe values. Any live parts at 230 volt ac are not accesable provided the plug top is not damaged. i.e. if there is no physical damage there is no danger. I take your point on the black market but again a PAT test would not be effective in detecting sub standard workmanship as this is down to the materials used level of segregation quality of build. To counteract this always buy from a reputable supplier etc
mark.g  
#19 Posted : 16 March 2010 08:45:48(UTC)
Rank: Forum user
mark.g

If by insulation resistance you are thinking between the live pin and the casing of the charger this is not necassary. The visual inspection would detect any damage and even poor quality plastic is likely to be an insulator. This test is between the live pin and any metallic parts on class 2 equipment such as screws etc not between the pins and any exposed plastic.
Grizzly  
#20 Posted : 16 March 2010 09:25:24(UTC)
Rank: Forum user
Grizzly

mark, You almost got there in the end! In PAT, the insulation resistance test in NEVER between line and neutral (for very obvious reasons, if you think about it), but rather between live parts (line & neutral combined) and earth for Class I, and live parts and exposed metal for Class II. On the majority of Class II chargers and other power supplies, the only, and most obvious, exposed metal part is the concentric barrel connector on the end of the output lead. This makes an ideal point to perform the IR test. Obviously, performing an IR test between live parts and the plastic casing would be a nonsense, and a waste of everyones time.
redken  
#21 Posted : 16 March 2010 10:23:39(UTC)
Rank: Super forum user
redken

Why is it that we have Portable Applicance testing (PAT) but not electrical equipment testing. And anyway what is the difference between a portable(electrical) appliance and an electrical appliance.
Grizzly  
#22 Posted : 16 March 2010 12:40:17(UTC)
Rank: Forum user
Grizzly

redken wrote:
Why is it that we have Portable Applicance testing (PAT) but not electrical equipment testing. And anyway what is the difference between a portable(electrical) appliance and an electrical appliance.
'Portable Appliance Testing' is rather an outdated term nowdays, but one that persists in usage (and hence the associated confusion). The correct term for the whole can-of-worms is 'In-service Inspection and Testing of Electrical Equipment', as outlined in the IEE Code of Practice: http://www.theiet.org/pu...ng/books/wir-reg/cop.cfm which covers all electrical appliances, from small, handheld through to large, fixed hardwired items.
Jacob  
#23 Posted : 16 March 2010 13:27:07(UTC)
Rank: Forum user
Jacob

Originally Posted by: Cruisin' Go to Quoted Post
Can anybody explain why computers are not PAT tested please? Are there any other items of equipment that should not be tested?
Hello, this is turning into interesting conversation about phone chargers, but back to the original question. I've been told, that regarding PC, only part which needs to be tested is the mains lead. Pc itself runs on low safe voltage. That's what we have been doing in past. I may not be right, just saying what we are doing.
paul.skyrme  
#24 Posted : 16 March 2010 13:31:18(UTC)
Rank: Super forum user
paul.skyrme

mark.g I concur with Grizzly over this. Also a small portable power supply such as a phone charger is unlikely to be a voltage divider, the transformer rectifier solution is more likely, it may also be a switched mode power supply these days. Also note that they are not a safety isolated device, there is the possibility under certain failure modes for the input voltage to appear at the output terminals. That is they are NOT, SELV, or PELV devices. They should be tested. IF that is the procedure that you wish to implement. Remembering that the IET CoP gives further guidance, as do various HSE and ESC guidance as has already been suggested. redken, Please see my comments below, All, Be very careful however, to take Grizzly's basically correct statement including large hard wired items for granted. Items such as wall heaters, built in appliances, large stationary appliances such as fridges, can be considered under a PAT regime quite easily. However, to undertake a full test on a wall mounted electric heater will necessitate dismantling and disconnection of aspects of the fixed wiring installation those undertaking such disconnections and reconnections should be competent to do so. A PAT course would not give you this level of competence. Safe isolation would be required as live working in this scenario would not be excusable. All the PAT in the world will not protect you if there are defects in the fixed wiring installation. If the portable appliance relies on the “earth” conductor in the fixed installation for its protective measures, if this is not present or inadequate then there is still a serious hazard even if the appliance has just passed its PAT and has developed an internal fault just after, or if the fixed heater disconnected and reconnected by the PAT person did not have its circuit protective conductor (earth) correctly reinstated after test. One must be careful of machinery built to BS EN 60204-1 standards, basically the machine equivalent of BS7671 (IEE Wiring regs). Applying the IET CoP to such equipment by unqualified personnel leaves a lot to desired, believe me I have seen it many times! Inspection and testing on large fixed machinery such as machine tools etc. is best left to professionals, PAT companies should be extensively interrogated in their competence to undertake any such work. rnighting, Whilst I see and understand your points, I fail to see the place for flash testing at 1k5V or 3kV during in service inspection and testing. This is specifically excluded as a requirement in the current IET CoP for in service I&T. Many PAT machines for several years now have had a low current earth bond test (around 100mA) which can be utilised to confirm the continuity of the earth bond, whilst minimising the current flow through the “appliance” which also could cause damage to equipment, remembering that a “normal” earth bond test provides up to around 25A for up to around 20s. As I understand the engineering behind this, as I have studied it, it is to highlight any possible high resistance or otherwise weak junctions in the earthing of the appliance. This is similar to the high current test that can be applied to metallic wiring containment systems such as conduit and trunking to confirm their earthing integrity is it not? Paul.
Grizzly  
#25 Posted : 16 March 2010 14:10:23(UTC)
Rank: Forum user
Grizzly

paul.skyrme wrote:
All, Be very careful however, to take Grizzly's basically correct statement including large hard wired items for granted. Items such as wall heaters, built in appliances, large stationary appliances such as fridges, can be considered under a PAT regime quite easily. However, to undertake a full test on a wall mounted electric heater will necessitate dismantling and disconnection of aspects of the fixed wiring installation those undertaking such disconnections and reconnections should be competent to do so. A PAT course would not give you this level of competence. Safe isolation would be required as live working in this scenario would not be excusable.
Absolutely agree, Paul. My point was to highlight that the CoP covered many types of appliance, not just 'portable'. I've witnessed many people who've been 'PAT' trained (C&G 2377 or similar), who think that now they are 'PAT testers', and the CoP covers hard-wired equipment, 3-phase equipment etc, that they now have to include such things in their schedule, totally missing the point that their training didn't even touch on those sorts of appliances, so they could hardly be considered competent.
Grizzly  
#26 Posted : 16 March 2010 14:17:52(UTC)
Rank: Forum user
Grizzly

Jacob wrote:
I've been told, that regarding PC, only part which needs to be tested is the mains lead. Pc itself runs on low safe voltage. That's what we have been doing in past. I may not be right, just saying what we are doing.
You're quite right to test the mains lead, which is a seperate appliance to the PC anyway. As for the PC itself, yes, most bits of it are running on extra low voltage, but the whole PC assembly still contains the power supply unit, which is supplied at mains voltage. Therefore, the PC is a 230V appliance, and can be tested accordingly (20mA - 200mA earth bond test, 500V insulation test (if PC is built to BS EN 60950)), and at the appropriate intervals for its environment.
jericho  
#27 Posted : 16 March 2010 19:53:04(UTC)
Rank: Forum user
jericho

I'm sorry, but are we suggesting that we agree that desk top PCs NEED PAT testing? Some very interesting technical talk about testing, but the original question was about the need or otherwise to PAT test a PC. Superb to hear from the inventor of the tester, but I presume that you were not the originator of the regulations? I can see no valid reason why you would want to do this, nor where the spirit of any regulation would require you to perform this test. The reality is that with a delicate electronic instrument such as a PC, any electrical fault shows up in a very manifest way. Usually it stops working! As we tend to replace PCs on a pretty regular basis and they do not have a physically hard life sitting there on a desk, I fail to see why you would spend time and money on this. A visual inspection during annual asset audit etc should be sufficient. Do we have evidence of computers that kill? We all have them in our homes and seem to survive. We even let our children use them. Do you have them annually tested like this? I think not. Please - let's get a grasp on reality here. We don't PAT test PCs, no. Test the mains lead? Get serious. Why? Because there is no need to. Drills, lighting units, transformers etc? Oh yes. Sure. Why, because it makes absolute sense. They get a battering and can end up with exposed / faulty parts that can lead to an electric shock. Not good. Sometimes I really do worry about where we are going. Doubtless there will be a furious backlash at my comments but frankly it doesn't change my mind. I see perfectly sensible legislation and guidance come in and get twisted and misinterpreted and it make me, well, you get the idea. Work at height - what was the 'sentiment'? To protect people whose 'work' was at height. What's it turned into? Risk assessments for using a step stool. And yet, people continue to be killed from falls from height. Really, we can end up looking in the wrong place you know. And yes of course I care about peoples' safety or I wouldn't be doing the job that I do. But before you reply, remember that the original question was about PAT testing computers to make sure that they didn't kill the users. Chris
Canopener  
#28 Posted : 16 March 2010 20:05:54(UTC)
Rank: Super forum user
Canopener

jericho/Chris - No backlash from me, I have on numerous occassions on this forum in the past tried to get people to take a reality check on this preoccupation with PA testing everything. I for one remain to be convinced that PA testing is in many cases a particularly good use of resources. My advice would be to apply simple risk based principles and have a look at both the HSE and IEE guidance, it is realively straightforward stuff.
Grizzly  
#29 Posted : 16 March 2010 20:25:36(UTC)
Rank: Forum user
Grizzly

jericho wrote:
Please - let's get a grasp on reality here. We don't PAT test PCs, no. Test the mains lead? Get serious. Why? Because there is no need to.
My point was that a PC can be tested, not whether it should or shouldn't be. That is entirely down to each company's risk assessment of their own situation. You don't test PCs? Fine. Other do? Still fine. As long as everyone is happy that they are meeting their statutory obligations, the you do what you think is necessary.
paul.skyrme  
#30 Posted : 16 March 2010 20:34:16(UTC)
Rank: Super forum user
paul.skyrme

I will echo Phil Rose & Grizzly's comments, however, I recently undertook PAT at a customers premises myself. I found, a cracked multiway adaptor feeding a PC workstation, multway adaptors all over the site, and a printer lead with a very high earth bond test, printer alone, OK, lead alone OK, both just, together fail. Customer has a blanket policy of PAT everything 12 monthly due to other areas in their organisation which do have appliances etc. that do need serious I&T. Being a competent electrician, electrial engineer (true engineer, IEng, MIET), and qualified & comeptent PA tester, and competent to test fixed installs as well as my H&S "hat" I try to be reasonable and applly common sense. When I got dragged out to test a few appliances the other day, (no one else available) around 30 I was told, came away with 91 test results. I advised the customer with regard to HSE & IET guidance on their equipment and how they could save resources on annual testing by adopting a risk based approach and following published guidance. Thier local H&S officer (multiple sites, large international blue chip co.) advised me that the management overhead to control multiple test periods outweighed the annual test everything approach! Paul Paul
paul.skyrme  
#31 Posted : 16 March 2010 20:35:08(UTC)
Rank: Super forum user
paul.skyrme

Can't spill tho' need spill chucker!
IanS  
#32 Posted : 17 March 2010 09:26:23(UTC)
Rank: Forum user
IanS

Just a quick observation Paul; you didn't need a PAT machine to identify the cracked multiway or to identify a plethora of such adaptors did you?
paul.skyrme  
#33 Posted : 17 March 2010 16:48:49(UTC)
Rank: Super forum user
paul.skyrme

IanS, No, quite right! This coupled with the other observations I made is why I suggested a more sensible risk based approach, looking at usage etc. These items could have easily been identified by user checks by a competent person, not an electrician, PAT trained person, or an engineer. However, they are sticking by the PAT everythign annually.
Cruisin' Susan  
#34 Posted : 19 March 2010 11:10:52(UTC)
Rank: Forum user
Cruisin' Susan

Thank you for all your advice, I certainly have a better understanding now of the issues surrounding PAT testing PCs and other equipment.
barnaby  
#35 Posted : 19 March 2010 15:16:10(UTC)
Rank: Guest
Guest

Grizzly wrote:
rnighting wrote:
As the inventor of the PAT Tester and the originator of the PAT testing activity and methodology over 20 years ago, perhaps I can reduce some of the myths and misunderstandings.
I think that if you're going to make claims like that, we need a bit more than a forum username to go on! - - - So, not that I don't believe you, but...
Hmmm yes! 20 years ago does seem a little recent. I recall testers being used in school science departments in the 1970s and I think it was used in some Government Departments in the 1960s!
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