2392/1 practical exam question

[robbo_blah]

Hi,

I am due to sit my 2392/1 practicals soon and during the course of my revision have come up with some un-answerable questions.

2392:
1. Are we required to perform live Zs checks in addition to working out Zs for each circuit?

2391:
1. what percentage Inspections should be performed on the exam (I know its 10% in real life unless a discrepancy is found?)
2. what is the correct procedure for testing the 3 phase elements (this was not covered in any detail on my course)
3. is the phase rotation test required to be done?

Also if anyone can provide me with the makeup of the individual boards within each exam, I would be most grateful!

Cheers

 

[SimpleSimon]

IQ you are a star.
Thanks for sort of putting my mind a little at ease!!!

 

[brucelee]

Hi mate there are 4 assessments he will just observe mainly and tell you what to do ie list 12 defects
first assessment is to find 12 defects from gn3 on a single phase ccu and a few circuits on a rig
earthing arrangments
tails correct size
exposed bare conductors
correct polarity ie lines ad neutrals not reversed
circuits identified
sequence maintained for lines neutrals and cpc
single pole devices in line conductor
labels
cable selection for current carrying capacity
swa armour earthed ie banjo earthed
ip ratings maintained ip4x top ip2x front and sides
etc etc
30ma rcd for additional protection
screws missing
sheathing not cut back to far not ie have to be inside enclosure eg pendants sockets switches
fire barriers /thermal effects
accessories correctly connected and no damage
bending radius of cables
cables correctly clipped ie no two cables in 1 clip ad cable not clipped on its side if T/E
cables not damaged
the list is endless matey
basically your looking for 12 but you may find more
you have 30 mins for this

assessment 2 is 20 mins IR testing to find two faults on another simple single phase rig ir test at tails first if faults located start breaking down testing individually
ie dead short 0.00M/ohm and low insulation resistance ie 0.02M/ohm
you have to tell him which its on and fill 2 small sheets in saying where the faults are ie dead short L-N

3rd assessmet 10 mins

earth fault loop impedence Zs use a plug in lead check to see if the circuits comply with max measured 80% values in gn3 to see if Zs low enough so they meet the max disconnection times
checking agaist the relevent table in gn3 for the appropriate protective device ie fuse or circuit breaker make sure your checkig correct type ie type B or type C
make sure you are checking the correct table for fuses if thats fuse as there are two one for 32a and under ie to meet the 0.4 sec max disconnection and for circuits over 32a is the the 5 sec table
you have to tell him if they pass or fail to meet max measured Zs from GN3

assessment 4 full pir of a three phase distribution board and a single phase ccu
first ask for old test sheets ie old pir then copy and fill in as much as you can before you start on the new pir then you only have to fill in the schedule of tests
check out what switches what before isolating helps you identify whats what ie operate switches to see what lights up ets for the 2 ways
ask permission is it ok to perform isolation ie switch off
perform safe isolation switch off lock off and retain key in POCKET OR FAIL
procede using approved voltage indicator check working ok first by
checking on a suitable proving unit before then test all to check for dead E-L, N-L, L-L, E,N should all be 0volts
check on proving unit again to see was working correctly at time of test


then inspection first
look for any defects sigle pole in line etc
then carry out all testing dead tests
on 3 phase first
continuity of main protective bonding R2 disconnect at 1 end ie from MET tick in box
continuity of protective conductors remove lamps and operate switches to help prove cotinuity polarity proved at same time for lighting circuits R1+R2 radial sockets have to check L-N also to prove polarity R1+RN
continuity of ring final circuit conductors ie 3 step test record results
IR at 500vdc on all circuits check voltage sensitive or electronic equipment removed or isolated ie turn rcd off at single phase board remove link from contactor of 3 phase motor circuit ie 3 phase socket dimmer switch
operate 2 ways on lighting to ensure all circuit is tested record results

then single phase dead tests

then polarity live at supply of three phase leave all installation isolated except supply test there
and at can use a socket and see to prove polarity by plugging into a socket
then Ze of three phase highest of the line to earths is Ze disconnect earthing conductor from MET to remove paralell paths Record result
then pfc highest of the line to neutral pscc eg L1-N, L2-N, L3-N multiply the highest value by 2 as this will always be higher than pefc on a 3 phase board and some testers cant measure between the lines which is the highest pfc but safer to measure L-N and double the highest this figure errs on the side of safety and is a rule of thumb the true figure is 1.732 but multiplying by 2 is easier and safer as its greater Record this value


circuits for three phase are
circuit 1 distribution circuit to single phase in armoured
circuit 2 ring
circuit 3 radial to a fused spur using MI cable
circuit 10,11,12 is the circuit for the three phase motor circuit ie socket outlet 3 phase

circuits for the single phase
circuit 1 radial socket outlet circuit R1+RN
circuit 2 two way lighting circuit R1+R2 OPERATE 2 ways to prove continuity and operate switches and conduct further IR tests to test all circuit is tested
circuit 3 simple lighting circuit with dimmer R1+R2
IR on all above
Ze at this board is the Zs for the distribution circuit form the three phase board or ze +(R1+R2) calc
PFC ie pefc L-E and then pscc L-N highest is the pfc for this board

Replace all covers to the boards and replace all links reconnect dimmer etc
then live tests on all only have to measure Zs on the socket outlet circuits the rest calculate from
Zs = Ze +(R1+R2) right calc at the side of the circuits you calculate in the remarks box
Zs of the circuit for supply to single phase is also the Ze or Zdb for this board ie single phase so you dont have to measure Ze again at the single phase
any circuits that have to high Zs to meet max disconnection times right it in remarks box at side of appropriate circuit record all results calculated or measured

RCD test on upfront rcd of single phase use plug in lead in the radial socket outlet half times no trip then record highest of the 1x both half cycles in column 13 for the rcd time and then record highest of the 5 x at both 0 and 180 cycles in remarks box at the side
PRESS THE TEST BUTTON
replace all lamps perform functional checks

think thats about it mate not sure of time for this it flew
dont panic just work in a methodical manner
i may of missed a few bits but not much lol
hope thats some help mate they will help if you ask eg to hold the contactor in why you test the 3 phase socket
and they will operate the switches why you do the 2 way ir testing if you ask
and they are not there to trip you just make sure you are competent

we didnt do phase rotation test

oh Iq is spot on listen to him matey

good luck by the way

 

[IQ Electrical]

Bruce, what a post, total recall!!!

I suggest anyone embarking on 2391-10 practical prints out Bruce's reply.
The circuit arrangements will be different though eg. one of my centres has the distribution circuit to DB2 fed in singles in trunking.

 

[CRAGS]

Nice post brucie takes me back.

Once you get in the flow of your testing you will be fine just be safe locking of safe isolation etc replace covers when done when testing live don't leave 2 covers off...

 

[brucelee]

Bruce, what a post, total recall!!!

I suggest anyone embarking on 2391-10 practical prints out Bruce's reply.
The circuit arrangements will be different though eg. one of my centres has the distribution circuit to DB2 fed in singles in trunking.

Cheers IQ mate
just wanted to give them a little help as i felt the 2391 a great experience but a little daunting as your not sure what to expect and i had to search everything i could when i was taking the course reading and writing loads i had no experience of testing 3 phase before i took the exam.
I too had to ask people about the practical part as i am not working yet as i am a full time carer
So because of this was unsure on what was involved and found the help i received of forum members and all the study a great help
just hope it helps them i some way

 

[brucelee]

Nice post brucie takes me back.

Once you get in the flow of your testing you will be fine just be safe locking of safe isolation etc replace covers when done when testing live don't leave 2 covers off...

cheers crags
yes was having a flash back at 2am lol
so have you done the re sit mate

 

[CRAGS]

Sat resit in oct mate results due bout 6th dec. Went better than last time but weather it was well enough who knows.

 

[brucelee]

hi mate
i am sure you will do it this time
i have finally had a letter from college saying my certificate is there for collection told them to deliver it instead as its about 25 miles away or so from me
they forgot to send the pratical part of it to c&g until october the muppets
so its due in the next few days
hopefully its in gold frame for the wait lol

anyway crags good luck to you matey you deserve it for your efforts i keep my fingers crossed for ya but i am sure you got it this time cheers

 

[CRAGS]

How long you have waited mate should be in gold frame and diamond encrusted

 

[brucelee]

june 10 th was exam waited over 12 week to find out if i had passed and altogether i have waited over 5 months lol
hopefully it will arrive this week or next as i have set the reply slip for them to post
will probably get lost in the post now lol

 

[SimpleSimon]

Bruce, I.Q thank you both so much for your help.
I took the test today and passed. I owe a big thank you to you both and every Spark who contributes on this site for the knowledge I used today to pass.
Very happy

 

[CRAGS]

Congrats

 

[IQ Electrical]

Bruce, I.Q thank you both so much for your help.
I took the test today and passed. I owe a big thank you to you both and every Spark who contributes on this site for the knowledge I used today to pass.
Very happy

Well done, it's a good feeling whenever you pass a test!

When's your theory?

 

[brucelee]

Well done Simon,
Its a great feeling after all the effort eh mate and a huge relief glad i could help in some small way as others helped me when i took mine
this site is great to get advice as and when needed
congratulations and good luck with the written exam

 

[Benny2]

Weldone pal, onwards and upwards!