c&g 2377


Postby ian00uk » Wed Nov 11, 2009 7:11 pm

im revising for my c&g 2377 pat testing exam and got hold of practice paper but dont have the answers. just a few questions im unsure of answers, wondered if anyone could help

1)Users of equiptment have a legal resonsibility to comply with both health and safety at work act and electricity at work regulations which of the following is NOT such a responsibilty
a. Raplace the fuse in the plug top following a fault
b. regulary inspect equiptment
c. assess the suitability of equiptment for continued use
d. Label, report and withdraw from service faulty equiptment.
2) The purpose of insulation resistance test is to ensure
a. fuses are adequate rating
b.insulation has not deteriorated below acceptable levels
c.the value of insulation resistance is below 1 M ohm
d. that live conductors are connected together

3)During an earth continuity test on an appliance the result keeps rising the most likely fault would be
a. loose connection in the plug top
b. too high fuse rating
c.insulation fault in the cord
d.incorrect polarity at the socket

4)extension lead lengths are limited by the:
a. type of cord material
b.total power rating of the equiptment
c. current carrying capacity of the cable
d. voltage drop

5) after comparing the results of previous and present tests, deterioration in class 2 equiptment would show as:
a. higher insulation resistance values
b. lower insulation resistance values
c. lower earth continuity values
d. higher earth continuity values


MANY THANKS
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Postby ericmark » Fri Nov 13, 2009 8:51 am

1)Users of equipment have a legal responsibility to comply with both health and safety at work act and electricity at work regulations which of the following is NOT such a responsibility
a. Replace the fuse in the plug top following a fault
b. regularly inspect equipment
c. assess the suitability of equipment for continued use
d. Label, report and withdraw from service faulty equipment.

The user does not replace the fuse so (a)

2) The purpose of insulation resistance test is to ensure
a. fuses are adequate rating
b.insulation has not deteriorated below acceptable levels
c.the value of insulation resistance is below 1 M ohm
d. that live conductors are connected together

Again the fuse has nothing to do with insulation resistance so (a)

3)During an earth continuity test on an appliance the result keeps rising the most likely fault would be
a. loose connection in the plug top
b. too high fuse rating
c. insulation fault in the cord
d. incorrect polarity at the socket

I would say non of above more likely some filter in the device to prevent EMC. But of options given then (a) is correct answer.

4) extension lead lengths are limited by the:
a. type of cord material
b. total power rating of the equipment
c. current carrying capacity of the cable
d. voltage drop

In a way voltage drop as the cable length increases so does it’s resistance and enough current needs to flow to operate the safety disconnection device. And volts are directly related to ohm’s but the current carrying capacity is also varied by the insulation material i.e. 60 degs C or 90 degs C so would have to be volt drop (d) but bad question as all have some bearing on length. To blow a 13A fuse in 0.4 seconds the maximum resistance is 2.42 ohms (page 48 of regs) and for a type B 32 amp MCB to trip you have a maximum of 1.44 ohms. So it is likely any socket will have a resistance of 1.44 ohms to start with. So the flex cable needs to be less than 1 ohm to be sure to blow fuse in 0.4 seconds. However once RCD’s are used then we are no longer concerned with the 0.4 second disconnection time and the flex can be longer and at 17 ohm it would still blow the fuse in a much longer time. However it would likely have an impact on the equipment long before that stage. Since most equipment has a minimum voltage of around 200 volts then a 30 volts volt drop in most cases would be maximum and with switch mode equipment i.e. Lap top then 130 volts volt drop would be max. So volt drop would be the limiting factor with an insulation to 17th edition. However since the item is portable and could be used with installation not complying to 17th Edition the limit of 1 ohms for 13A fuse is still what should be considered as limiting factor unless a RCD plug is fitted.

5) after comparing the results of previous and present tests, deterioration in class 2 equipment would show as:
a. higher insulation resistance values
b. lower insulation resistance values
c. lower earth continuity values
d. higher earth continuity values

Well it says Class 2 so that knocks out two answers so has to be (b)
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Postby ian00uk » Fri Nov 13, 2009 12:21 pm

many thanks. apriciate it
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Postby moggy1968 » Fri Nov 13, 2009 7:43 pm

with regards to question 3, if there is a loose connection then this will cause a build up of heat, which will increase the resistance, hence why the continuity reading would increase, hence why A is correct, that and the fact none of the others are right!!! if you don't know the answer you can often whittle it down by process of elimination!
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Postby sparx » Fri Nov 13, 2009 8:00 pm

hi, have to disagree with
answer 2, it is imho b)
the whole point of PAtesting is to spot early deteriation of a reading so the equipment can be taken out of service before total failure eg flex breaking down with ever lowering IR readings, which is the reason for having to keep records rather than just 'go-nogo' pass levels,
I think Ericmark misread the question,
regards Sparx
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Postby ericmark » Fri Nov 13, 2009 9:11 pm

[quote="sparx"]hi, have to disagree with
answer 2, it is imho b)
the whole point of PAtesting is to spot early deteriation of a reading so the equipment can be taken out of service before total failure eg flex breaking down with ever lowering IR readings, which is the reason for having to keep records rather than just 'go-nogo' pass levels,
I think Ericmark misread the question,
regards Sparx[/quote]
Yes I had put in wrong letter it is of course (b) I did say the fuse has nothing to do with insulation resistance so I'll blame typo error was not looking properly at options.

All questions there are two things to look at. 5) For example says Class II so there will be no earth continuity so only two left. deterioration will lower insulation resistance values. So looking at what it's not is also important.

Although we are to look for trends the portable appliance testing is often done on the hoof so carrying all past test results to compare before the pass or fail is mainly theoretical except for where the tester stores the info.

However not all testing of in service equipment is concerned with portable equipment in the way one expects using a purpose made machine.

Each month I tested part of our portable batching plant. (It did have wheels came as 6 wagon loads) The engineer has split the testing into 4 groups designed so two men could test 1/4 per day so every 4 months all would be tested at 1 day (Sunday) per month. (Three plants and 3 guys so each guy worked every other Sunday) With such inspecting and testing all results were entered on an Excel spread sheet and insulation was monitored. Often low insulation was due to concrete dust across contacts getting damp and using a vacuum cleaner to remove dust was all part of the service.

Also items like safety switches were also included in the tests and we had to ensure removing panels would auto stop the machine. I was not just the shock dangers we tested for but also all electrically controlled safety systems.

C&G 2377 is not just items under 18 kg in mass that is intended to be moved while in operation or an appliance which can easily be moved from one place to another. It also includes the other categories. I will admit the batching plant is a little more than most people test but when one agrees to inspect and test all in-service equipment in a building one could find the odd hand dryer which is not part of building fabric but is hard wired and requires access to distribution boards to isolate and test.

Hence why some questions seem rather odd. It is of course impossible to test any ones ability with two short exams and once you start inspection and testing you will start to learn. I had all sorts of adaptors and tools to make life easy and we often wrote our own procedure including holding in contactors to do IR sets where the machines were three phase and we could not run them through the PAT tester.

Passing the exam like the driving test says your good enough to start testing you will never stop learning.
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Postby moggy1968 » Fri Nov 13, 2009 9:23 pm

Its B for Q2 by the way
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