Question Time
Need to know something? Then Bob’s the man to ask.
test) in order to gain a reading from the tester? If not what are the options available?
Q A
The IET defines within its code of practice that the Earth Bond test must be carried out on accessible metal parts. In reading your post I am assuming that
you intend to probe somewhere internally on the unit via a grate or mesh. What we are trying to achieve by performing an earth bond test is ensuring that any part a user can touch has a sound connection to earth, so in the case of a fault that metal part cannot become live and give the user a shock. Therefore if you cannot get a connection with your probe, it is probably also true that a human finger cannot contact this metal part. You really have two options at this point - contact the manufacturer of the equipment and ask them how they recommend the item to be tested or test the item as a class 1 product but omit the Earth Bond test from the sequence. Do not test the item as Class 2 as the limits are different. However when omitting the Earth Bond test, ensure that your notes state that you have no accessible metal parts, and that an Earth Bond test was not suitable.
told not to bother testing IT, only do a 'FVI' as the risk of damaging IT is expensive.
Using the appropriate test settings will avoid damage to IT equipment. Formal visual inspection is essential but won’t necessarily pick up all problems, such as a poor earth connection. For example it should be possible to carry out a Earth Bond test at 100mA at a 0.50 ohm limit and test the IEC lead separately as normal.
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Is it really necessary to actually test IT equipment as well as carry out a 'formal visual inspection'? The reason I ask is at college we were
Is it ok to test a class 1 appliance that is made entirely from plastic, with a screwdriver jammed in the earth pin of the appliance (probe
resistance test ineffective. As a general rule an appliance must be switched on in order to correctly perform an Insulation Resistance test, otherwise the test is only performed up to the switch and not the whole appliance. Therefore we have no idea if the insulation is sound. A leakage test in these circumstances can be performed in its place. An appliance failing an insulation test will also give a failed leakage test. Manufacturers are frequently adding electronic switches to devices now and unless power is applied to the unit the switch cannot be closed. Therefore an insulation test is not really appropriate when testing such appliances, and a leakage test is much more appropriate.
IT Equipment that does not comply with BE EN 60950 may also be damaged by a 500V Insulation Test and in these circumstances a test with no insulation may also be more appropriate.
Q A
I am responsible for arranging inspection and testing of all equipment in the offices where I work. I have checked past test records and
every office item has been tested every year including stationary and IT equipment. However, according to the IEE Code of Practice the recommended interval for the next test is up to 2 years for a formal visual inspection and 4 years for a combined test and inspection. Is an annual inspection the norm or should I be testing more frequently?
You are correct that the suggested initial frequency of inspection and testing for office IT equipment recommended by the IEE Code of Practice ranges between 24
and 48 months, depending on the class of construction.
The IEE Code does point out that this is the "initial"
How do I recognise a device with no insulation (NI) when I am out testing?
The NI tests are performed on an appliance where an insulation test is not appropriate. There are various factors which may determine an insulation
frequency and that the frequency of inspection testing depends upon the environment, the user and the equipment. The reality is that this is a judgement call - there are no right or wrong answers. The Electricity at Work Regulations (which is the legislation we must comply with) says that we must take "reasonably practicable steps so as to prevent danger" so must decide, normally by risk assessment, what is reasonable. We might argue that IT equipment sitting in an office is unlikely to develop a dangerous fault - the problem arises when you add people into the equation - a cup of coffee spilt on the desk, cables moved around, wedged under a desk leg. Why not contact the company who do your testing, tell them that your understanding is that the IEE recommend testing every 24-48 months for your
particular equipment and ask for their views.
they are connected. Also most B&B do not believe they have to have appliances tested at all – is this really the situation?
Q A
The IEE Code of Practice for In-Service Inspection & Testing 3rd edition recommends the frequencies of inspection and electrical safety testing
for different sectors of industry. For example, Items in B&B rooms are classed ‘Items Used by the Public’ and for handheld items such as a hair dryer, for example, normally a Class 2-combined visual inspection and test would be required every 12 months. A formal visual record of the equipment condition should be made every month. If staff in the B&B use electrical equipment such as a floor cleaners (and other ‘portable appliances’) a combined visual record and test must be taken every 24 months and a formal visual record every 12 months. A record of all results should be recorded and kept for the life of the equipment; that way whoever is carrying out the PAT testing can see if there is any deterioration in the appliance insulation, or plug condition etc.
It is not necessary by law to have items PAT tested, However if there was a fault in the equipment which led to an injury or death, as the business owner you would have to prove to the HSE or the Courts that your maintenance regime for electrical equipment is better than or is equal to that laid out by the IEE Code of Practice and the HSE Guidance Notes. When it comes to Health & Safety YOU have to prove your innocence – by showing that all reasonable steps have been taken to avoid injury or accident.
What is the situation with test periods for different products? I know PCs are ok for at least 2 years, but not the extension leads to which
Thanks for some great questions – Keep them coming and look out for future TechTalk articles covering these topics.
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