pat testing questions

Bad luck on the test, but perhaps better to understand it fully before being released into the wild!  I have no idea what is in your PAT syllabus, so cannot comment on if the tutor was directing you to the right info or not,  but I'll have a go at the queries. Easy one first

gs38 - guidance for probe tips on meters and when you need precautions like fused test leads,


How good is your understanding of how things like RCDs and fuses work ?  If the below makes no sense, then some more background reading is needed, so if need bo feel free to come back and I can point you to that.

question about current rating of what ? do you know how to select the right  fuse  for a plug or fused spur? Was this about test kit with larger sockets? -the needs for  63A 3 phase plugs are a bit different to those for shavers..


RCDs that are intended to save lives, as opposed to save wiring from damage, have to remove the power in less than a heartbeat - typically 0.4 of a second for systems like 230V mains on TN supplies, where a max shock voltage of 115 is assumed. ).2 seconds in situations with a high impedance earth where the shock voltage may be the full supply voltage. Actually in a modern installation nearly all 13A sockets are fed by an RCD of sime kind, but the high risks are hand held things, and stuff used where it may be wet, like outdoor, or bathrooms/ swimming pools etc.

I get how the rcds work and thier purpose. The thing is the iet book for code of practice for in service inspection and testing of electrical equipment and the tutor made no reference to outdoor sockets and appliances.


Question I have is, are the trip times, trip ma value, rcd amp size the same as your standard 32amp indoor ring mainspring? And what is the minimum I.p rating for outdoor sockets?

Hi

like mapj1, I'm not sure what is in your syllabus. But a quick scan through IET code of practice (4th Edition) states in 4.2 that any rcd used to provide protection for equipment used outdoors "is required to have a residual operating current not exceeding 30 mA at 40 ms."


Would this have been enough to answer the question, or was more detail required?


(out of interest, what is the format of the exam? Is it multiple choice and open book?)

It is indeed open book and multi choice. So what is the rcd amp values for oitdoor sockets? 32a? And is the minimum ip rating ip64 or 68?


Thanks for the answers guys.

I think that it is unfair to indicate the tutor failed to present info that you were asked questions on. The whole idea is proving competenacy and an adequate working knowledge of the subject. Any tutor that just delivers training that specifically answers likley exam questions is to me failing their students and unfortunately something we all see far too often now that focus is on teaching to get passes rather than teaching to ensure the student has a sufficient knowledge of the subject or in this case the  information and detail IET code of practice (4th Edition) that no matter the question the student has the ability either to know the answer straightaway, find the information in the COP and/or apply the information in the COP. Im presuming it was the City and Guilds exam? or perhaps another awarding body, but they will not be asking questions that answers cant be found in the COP.


There are certainly great and not so great trainers/tutors out there and great and not so great training establishments. But the student needs to take responsibility as well.


GTB

This thread isn't to debate the competency of the tutors. But as you directly addressed that matter, the tutor failed to cover topics that where likely to come up in the exam. He also stated a pass mark of 70% but is actually 80% so how competent can a tutor be if they don't know the pass mark of the exam they invigilate? The tutor in question had more interest in discussing topics not relating to the course than the course content and I dont feel I was given enough information to sut the exam with a fair chance of passing. Those 2 subjects that the tutor didn't cover at all amounts to 10% of fhe pass mark for the questions I got.


However I do agree a tutor who gives the answers to exam questions instead of addressing the topics and teaching those topics would be a bigger failure as its jist cheating. But they have to cover enough of the subject to give students a fair chance of passing

"is required to have a residual operating current not exceeding 30 mA at 40 ms."

Usually the requirement for 30mA RCDs providing additional protection is something closer to 300ms at a residual current of 30mA and 40ms at 150mA.

And is the minimum ip rating ip64 or 68?

IP ratings have two parts - the first digit indicates protection from solid objects (e.g. fingers) and the second against liquids (usually water/rain).


IP6X seems a bit steep for a socket - ordinary sockets often struggle to get any higher than IP2X due to the openings needed for the plug's pins - but if it's assumed that it has a waterproof cover that's in place then IP4X would be reasonable minimum for most circumstances (in general enclosures need to meet IP4X for their top surfaces) and IP5X would be common at least for domestic outdoor sockets.


For the liquid part, it depends on the circumstances, if it's sheltered (e.g. outdoors but under cover) it might not need anything special at all, if subject to just falling rain (sheltered from side winds) then IPX3 might do - IPX4 would provide protection from water sprays from any angle which should suit most weather conditions and IPX5 would provide protection from water jets from any direction (so suitable where the worst case would be a mis-directed hosepipe). IPX8 is for long term total immersion - which seems a bit OTT for most situations where you might be wandering around with a plug in hand.


  - Andy.

I'd say worst case would be a pressure washer rather than hose pipe, the thing is certain outdoor appliances have to be safe from penetrative from a wire, so i figured a socket would need either that level or higher of solid object penetration.

I used to tutor this course but quickly became disillusioned by the calibre of candidate and attitude of the Centre. The course was intended for those with a good grasp of electrical systems like electricians, maintenance technicians and the like but instead it was often populated with folk who had absolutely no idea of such things. City and Guilds recommend 35 hours for guided learning with a total qualification time of 40hours and make a requirement that the Centre carefully vets candidate capability. When I first ran the course it was over one day. So there should have been no chance for delegates who came with no electrotechnical understanding, yet many passed both the online and simple practical assessment. Regardless of their shiny new certificate and despite a stern warning from me that they had much to do to be deemed competent, they were released back to employers who thought that their storeman, joiner or painter and decorator was now a fully qualified operative able to make determinations on the safety of electrical equipment!