Basic Testing Procedures

[Barneyb57]

well I aint been here for ages,, but still loads of good info on here,,,,leaving the Forces soon so Ive been doing some courses just to refresh and some cases update my quals from years ago,,,I last did the 15th Edition when on the tools,,,,I have done recently the DEI and Part P,,,JIB ECS and a few weeks ago the 17th Edition,,,got my certificate today infact,,,Im am on a Inspection and testing course 2391 at the moment,,,and what a bitch of a course it is,,,cant see that they have a very high pass rate on this one,,,confused the crap out of me if Im honest,,,,practice test papers???? thye dont tell you where to look,,some of its in the regs book,, some of its in the GN3 Book and a few bits in the osg,,,,not very confident about passing this course,,,,did the others ok no problems but this one is a different kettle of fish,,I Was looking to get back in the trade but I AINT SO SURE now????
any one got any tips on how to find the answers in the books quickly...and any tips on the inspection and test bit which Im doing tomos....written test on Friday,,,dreading it,,if its anything like then practice papers we are getting on the course,, 5 day course and mind blowing to say the least.......Help!!!!

 

[Zorro]

You Have to remember this is closed book and always use correct terminology, read GN3 and OSG, also remember to read the scenario and underline all relevant parts of it, is it a new or old installation or even both, use bullet points to describe let's says insulation resistance.
For volt drop use ohms law IxR= V and the 1.2 factor may be needed depending again on scenario.
Learn the 18 point check list.
The earth fault loop impedance paths which you might need to draw or describe the components of it.
Learn the IP codes ipxxb/ip2x and ipxxd/ip4x.
For the practical do the 3 phase fisrt seek permission to safely isolate supply. Now do all continuity tests first i.e the feed supplying DB1 to DB2 then the fcu, motor starter do a R2 test on commando socket leave the ring final circuit until last do step 1 end to end resistance of r1 , rn and r2 then X connect line and neutral and then X connect the line and cpc remember r1 +rn/4 and r1+r2/4 the highest value on sockets will be recorded as your big R1+R2, record all readings on back of the schedule of inspections sheet so the assessor can see your values.
Insulation resistance Do all lives to lives and all lives to earth the are 10 insulation tests, remember to remove all sensitive equipment which may give false readings
With main switch in the off position Do your Ze test make sure you take out earthing conductor for this test , then replace earthing conductor after this test. Now do PSCC and PEFC still with main swith off remember on 3 phase times the PSCC by 2 this will be recorded as your PFC.
Do Zs of sockets but for fcu and motor starter do by calculation Ze+ R1+R2 = Zs
Now do the single phase. Remember follow this sequence safe isolation,Continuity of the lighting circuits remember to operate the 2 way switch on lighting circuit, continuity of the 1 way lights, Continuity of the radial socket, ,Insulation resistance when doing the 2 way lighting operate 2 way light switches so you include strappers , polarity dead, polarity live, Ze test, Zs tests for lighting circuits do by calculation and for radial socket do by direct measurement , PFC's, RCD test and functional testing. Sorry if I've missed anything but its 4:13am and I'm knackered.

 

[Barneyb57]

Zorro thanks for that,,,this is basicaly what we have done we have only had one dry run is pairs on a practice rig up until today 2 have failed already one for not making sure one of the tips on one of his test leads had a shroud on it, which made it conform to GS38,,,Banf out you go failed on safety,, and another failed on safety again, when proving dead,,,asked permission to swith off,, switched off and locked off all agreed by assessor,,,,removed 3 phase board panel cover,,,,with an approved test lamp and proving device,, proved lamp was working, proved by testing across L1-N L2-N L3-N and to earth that the supply was dead and again across the 3 phases,,,all dead,,,carried on with inspection and test,,,,,STOP!!! Sorry you have failed,, you didnt prove the test lamp in the proving device after testing the incoming supply was dead.....which it was....and had been certified....,,,is that fair and just???? I could understand it if he didnt prove the test lamp was working ok before testing that the supply was off,,,,but having already proved the lamp and that the supply was dead is a bit ---- to say the least,,,,,it was dead it was isolated and locked off!!!

 

[Zorro]

Seek permission to isolate the supply on a known suppy prove the dedicated voltage indicator is working correcly lock off post warning labesl and keep key on you you then become the duty holder. Test between all lives and all live to earth after you have locked off re-prove the dedicated voltage indicator again to make sure it is working correctly. Select the test equipment check condition of tester leads and battery condition this is done prior to testing when doing continuity testing make sure leads have been nulled out if you do not do this you will have incorrect values. Inbox me and if you want I can call you and go over stuff. You have also got to do 1a or 1b fault finding board, they have 13 faults on them to find. Then you have the IR board to do and finally the Loop board to do.

 

[Barneyb57]

That's all very well, but on the 2391 time is short - and in the real world, time is money.

Consider this:

Whilst performing safe isolation of the installation you have your voltage tester in your hand -

so you might as well perform the same tests on the incomming side of the main switch and confirm

supply polarity.

Then, as you have the cover off the board anyway, disconnect the earthing conductor and measure

Ze

Re-connect the earthing conductor and measure your PFC

These three tests have took you 5 minutes and you haven't moved.

Then onto your sequence of tests - continuity, ring final, IR, Polarity

Now, really speaking, you should put the cover back on the board before re-energising. (HSE and all

that) - but that's okay, because your finished in there and shouldn't have to take it off again

On with the remaining live tests - Zs, RCD and the functionals.

Job done.

Your not doing anything wrong - it's just more efficient

I Agree with you,, but I think alot of it depends on the ethics of the person testing/assessing you at the time,,,some are very strict in their ways of assessment,,,as in if you dont do it in the order they want it done,,they may well fail you,,, why because they can I suppose....on the course I just done it was their way or the highway,,,,and they taught and used the Crippler way....a couple failed the Practical within minutes....one because he didnt prove the test lamp after he had gotten permision to lock off off and had isolated the supply and locked off which was confirmed by the assessor,,,,he proved it before testing but didnt prove it again after ascetrtaining that the board he was working on was dead. the other one of the shroud tips on one of his test leads came off he didnt notice it and went to perform a test,,,,,oops sorry you failed......abit harsh I think,,after all look at your test leads,,,they have finger guards half way down the probe,,so put your finger tip on the end of the probe is very unlikely,,,,I guess the only other thing is the chance of a short circuit but thats unlikely on a terminal that is recessed and surrouned by plastic??? and as for the test lamp thing well the assessor had already confirmed with the student that the supply was off isolated and locked off,,and had been tested dead,,,,,I could understand it more had of forgotten to prove the test lamp before actually testing anything....good way of raising extra revenue, by re-tests I suppose...didnt prove that the guys in question were incompetent or unsafe as I see it...everything else they did over the 5 days was ok....

 

[SALectrics]

Very useful to newly qualified electrician

 

[Lspark]

Hi guys. I'm new to this, but great thread very useful thanks.

 

[Zorro]

Lspark are you doing your 2391? And is this the last one in March.

 

[Lspark]

Sorry I meant I'm new to the forum. I did my 2391 2 years ago now.
From what I heard the last one was a couple of weeks ago as a friend sat it. I may be wrong though.

 

[Zorro]

The last one is in March now. This is more than likely for the resits from December 6th 2391 written exam, but who know with City&Guilds they might extend even longer???

 

[se7aq]

Ok then, 17th 612.3.3 states that when the circuit includes electronic devices which are likely to influence the results or be damaged, only a measurement between the live conductors (live and neutral) connected together and the earthing arrangement shall be made.

Does it mean just that connect the red/brown and the balck/blue together and then test..?

As I have this house which is very very difficult to get at all the sockets and unplug all sockets due to the amount of items in the rooms, its a bit like a hoarders house but not as bad, but bad enough to not to be able to get to the sockets.

 

[Plonker 3]

Yes that's correct, but your dead tests should be used to verify the live conductors. Do not rely on the colour of the core to verify this.

 

[paddyscouse]

just a little tiny miss on your ze, it is actually line nuteral and earth test not just line and earth...........

 

[Sintra]

just a little tiny miss on your ze, it is actually line nuteral and earth test not just line and earth...........

Why would you test the neutral on an earth loop impedance test. Please elaborate.

 

[paddyscouse]

Why would you test the neutral on an earth loop impedance test. Please elaborate.

why because thats what the regs say you haft to do acording to 7671 ?