2391 sum practical help

[bobby101]

Procedure for testing

Lock off procedure

· isolate installation
· lock off and place key in pocket
· post warning notices


Prove dead as per GS 38 recommendations:

· Select an approved voltage tester that conforms to GS 38 requirements
· Use a proving unit to ensure correct operation of test lamp
· Apply test lamp to supply terminals to prove dead
· Re-use proving unit to check, test lamp operation

Continuity of protective conductors including main and supplementary bonding

R1 + R2 METHOD 1

· Select a low resistance ohmmeter
· Check condition of instrument
· Check the meter is within calibration date
· Check the instrument is zeroed
· Check the condition of the leads and probes
· Check that the resistance of the leads and probes is nulled out
· Connect the line conductor to the protective conductor at the distribution board
· Test between line and earth terminals at each outlet in the circuit
· If there is any light switches in circuit, operate them also include strappers into test
· Record highest reading at the circuits extremity this will be R1+R2


Long lead method

· Connect one terminal of the continuity tester to the installation main earth terminal
· Connect the other lead to the circuit protective conductors at various points in circuit


Main protective bonding conductors

· Disconnect the main protective bonding conductor at the water/gas supply or structural steel end
· The reason for this is to avoid parallel paths
· Connect the continuity tester to the main earth terminal
· Connect the continuity tester via a long lead to the end of the disconnected main protective bonding conductor, where situated at the gas/water supply
· The reading should be no more than 0.05Ω

Continuity of ring final circuit conductors

· Step1
· Disconnect ring circuit at distribution board
· Measure end to end resistance ( L-L ) ( N-N ) ( E-E ) and record results
· Step 2
· Connect the incoming line conductor of outgoing neutral conductor
· Connect the outgoing line conductor to incoming neutral conductor
· Draw a table and record results of the resistances at each socket between line and neutral (including spurs)
· Step 3
· Connect the incoming line conductor of outgoing earth conductor
· Connect the outgoing line conductor to incoming earth conductor
· Measure and record the resistances at each socket between line and earth (including spurs)
· Record results in table
· This has the benefit of giving a R1+R2 reading
· Confirm results by calculation from end to end resistances readings
· For step 2 ( L+N / 4 )
· For step 3 ( L+E / 4 )

 

[bobby101]

Insulation resistance

Single phase

· Select a insulation resistance tester
· Check condition of instrument
· Check the meter is within calibration date
· Check the condition of the leads and probes
· Disconnect all loads
· Disconnect any sensitive equipment
· Ensure no connection between line and neutral
· Disconnect any vulnerable equipment
· Ensure all circuit breakers are on
· Ensure all light switches on
· If there is a two way lighting circuit the strappers must be brought into test
· Place temp link between line busbar(s) and neutral busbar(s)
· Set instrument to 500v d.c.
· Apply test probes to line busbar and earth
· Record result
· Disconnect temp link
· Apply test to line busbar(s) and neutral busbar(s)
· Record result

Three phase

· Select a insulation resistance tester
· Check condition of instrument
· Check the meter is within calibration date
· Check the condition of the leads and probes
· Disconnect all loads
· Disconnect any sensitive equipment
· Ensure no connection between line and neutral
· Disconnect any vulnerable equipment
· Ensure all circuit breakers are on
· Ensure all light switches on
· If there is a two way lighting circuit the strappers must be brought into test
· If the main isolator is a three phase isolator the neutral must be disconnect for the duration of the test then reconnected after testing
· Set instrument to 500v d.c.
· Link neutral and line busbars together and measure the insulation resistance between all live conductors and earth and record the reading
· Next measure between all the lines linked together and neutral and record the reading
· Next measure the between each pair of lines and record the reading


Polarity

· Use a low resistance ohmmeter
· Conformation of R1+R2 will verify light circuits
· For radial circuits the R1+R2 measurements made as in test method 1 should be made at each point
· For ring circuits if steps 1,2 and 3 have been carried out this will confirm correct polarity
· check all single pole and protective devices are connected to the line conductor only
· the centre contact of screw type lampholders must be connected to the line conductor only except for E14 and E27 lampholders to BS EN 60238
· the line connection in socket outlets and similar accessories must be connected to the line conductor only

 

[bobby101]

Earth fault loop impedance

Ze

· Use an earth fault loop impedance tester
· Check condition of instrument
· Check the meter is within calibration date
· Check the condition of the leads and probes
· Ze must be made at the origin of the installation
· The installation must be isolated from the supply before earthing conductor is disconnected
· disconnect the main earthing conductor (this will avoid false readings due to parallel paths)
· connect the line and neutral probes to the incoming side of the main isolator and the earth probe to the earthing conductor test and record the result
· reconnect the earthing conductor
· on a three phase supply measure Ze between each line and earth and record the highest reading

Zs

· Use an earth fault loop impedance tester
· Check condition of instrument
· Check the meter is within calibration date
· Check the condition of the leads and probes
· The circuit must be live
· All earthing and bonding must be connected
· For radial/lighting circuits
· Using an earth fault loop impedance tester go to extremity of circuit and apply test probes to the line conductor, neutral conductor and circuit protective conductor
· Test and record result
· If test trips circuit breaker apply calculation of Zs=Ze+(R1+R2)
· For socket circuits
· Using an earth fault loop impedance tester go to every socket and plug in tester taking note of results, recording the highest result


RCD testing

· Please note for RCD,s BS rated the I∆n 30mA should trip within 200ms the BS EN rated RCD’s I∆n 30mA should trip within 300ms
· Test on both the negative and positive half cycles of the supply
· Check the RCD does not trip when a test current of 15ma is applied
· Check the RCD trips within 200ms or 300ms
· Check the RCD trips within 40ms
· Apply functional test to integral test button


Prospective fault current

· Use an earth fault loop impedance tester set to pfc testing usually 20ka, 20Ω TN system 200Ω TT system
· Check condition of instrument
· Check the meter is within calibration date
· Check the condition of the leads and probes
· The circuit must be live
· Apply test probes to line and neutral of the incoming supply the third lead also connects to the neutral
· test and record the result
· apply test probes to the incoming line, neutral and main earthing terminal this will give a reading for prospective earth fault current
· the higher of the two readings is taken as the prospective fault current

Three phase systems

· measure the prospective fault current between each line and neutral the third probe also connect to the neutral
· apply test probes to each line, neutral and main earthing terminal this will give a reading for prospective earth fault current
· the higher of the two main readings is taken as the prospective fault current


three phase rotation testing

· select a rotating disc type or indicator lamp type
· apply probes to individual lines L1,L2 & L3
· confirm correct phase sequence

Functional testing

· ensure all light switches, circuit breakers, main isolator, sockets, etc all function correctly

 

[breakerman]

wow, i'm srating my 2391 2mos, i'm down loding this stuf ...it's absoultly spot on..cheerzz a big one

 

[brucelee]

Earth fault loop impedance

Ze

· Use an earth fault loop impedance tester
· Check condition of instrument
· Check the meter is within calibration date
· Check the condition of the leads and probes
· Ze must be made at the origin of the installation
· The installation must be isolated from the supply before earthing conductor is disconnected
· disconnect the main earthing conductor (this will avoid false readings due to parallel paths)
· connect the line and neutral probes to the incoming side of the main isolator and the earth probe to the earthing conductor test and record the result
· reconnect the earthing conductor
· on a three phase supply measure Ze between each line and earth and record the highest reading

Zs

· Use an earth fault loop impedance tester
· Check condition of instrument
· Check the meter is within calibration date
· Check the condition of the leads and probes
· The circuit must be live
· All earthing and bonding must be connected
· For radial/lighting circuits
· Using an earth fault loop impedance tester go to extremity of circuit and apply test probes to the line conductor, neutral conductor and circuit protective conductor
· Test and record result
· If test trips circuit breaker apply calculation of Zs=Ze+(R1+R2)
· For socket circuits
· Using an earth fault loop impedance tester go to every socket and plug in tester taking note of results, recording the highest result


RCD testing

· Please note for RCD,s BS rated the I∆n 30mA should trip within 200ms the BS EN rated RCD’s I∆n 30mA should trip within 300ms
· Test on both the negative and positive half cycles of the supply
· Check the RCD does not trip when a test current of 15ma is applied
· Check the RCD trips within 200ms or 300ms
· Check the RCD trips within 40ms
· Apply functional test to integral test button


Prospective fault current

· Use an earth fault loop impedance tester set to pfc testing usually 20ka, 20Ω TN system 200Ω TT system
· Check condition of instrument
· Check the meter is within calibration date
· Check the condition of the leads and probes
· The circuit must be live
· Apply test probes to line and neutral of the incoming supply the third lead also connects to the neutral
· test and record the result
· apply test probes to the incoming line, neutral and main earthing terminal this will give a reading for prospective earth fault current
· the higher of the two readings is taken as the prospective fault current

Three phase systems

· measure the prospective fault current between each line and neutral the third probe also connect to the neutral
· apply test probes to each line, neutral and main earthing terminal this will give a reading for prospective earth fault current
· the higher of the two main readings is taken as the prospective fault current


three phase rotation testing

· select a rotating disc type or indicator lamp type
· apply probes to individual lines L1,L2 & L3
· confirm correct phase sequence

Functional testing

· ensure all light switches, circuit breakers, main isolator, sockets, etc all function correctly

Hi mate very useful post
I was just looking through and noticed on the three phase PFC you have forgot to mention
you have to multiply the highest Line to neutral value by 2 this is then recorded
as the highest pfc will be between the lines some testers canot measure this this is why you multiply by 2 cheers

 

[bobby101]

yeah you got me there but hey if you aint got the questions you cant find the answers ......... by the way totally happy i am a senior wow happy days BTW that does not mean i am old honest my kids will tell you that oooops ha ha yey happy days plod on also on a personal note i used most of the information here on bullit points both as a reminder and as a good practical aid to help me pass the 2391 and it did.
stud study, then get as many 17th edition 2391 past papers as poss study please note when buying from ebay please contact buyer to find out if it its 17th cos i got duped many times and yet the chancers are still selling past papers for 16 th edition which dont get me wrong can help but when messing with new terms and terminoligies (not sure i spelt the last word right but f it iam slightly p 1 sse d yep) good luck 2 u all happy days ....PS PASS MARK FOR 2391 IS AROUND 80 % SO I HAVE BEEN LED TO BELIVE MAJOR POINTERS EFLI DIAGRAMS AND INS CALCS ARE GOOD 2 KNOW ALSO GET A COPY OF JUNE 2391 PAST PAPER THAT WOS THE BOMB LEARN VOLT DROP AND PHASE ROTATION, DO THE SEARCH FOR THE 2391 ALL THE INFO IS THERE IF YOU SEEK THE ANSWER THE QUESTION IS NOT THE PROBLEM......................ONLY FOOLS TEST WITH THEIR TOUNGE OR LUCKY IDIOTS .......
REMEMBER IAM TRAINED IDIOT OR AN IDIOT THAT WOS TRAINED ARF ARF....OOHH HAAPY DAYS I WISH YOU ALL WELL GOOD LUCK. ALLS WELL THAT BLOWS SO I KEEP TELLING THE WIFE . ARF ARF .

 

[Sparky Ninja]

Can I ask if this was copied or if you made it up yourself?
It's not a copyright question, it's just some of the text is incorrect or inconsistent with what the IEE has supplied me with, and if a training centre or college is using this it would be of interest to them.

Thanks for sharing BTW

 

[bobby101]

hiya m8 please clarify coz i think most of it i got from several books then made them into bullit points cant really remember to be honest it was at the time i was studying and it made sense to make this up both as an aid for me and at the time i ithought if i post it and it gets nitpicked then i will know exactly where i was going wrong i was put up as both a question for me and a possible aid for others if that makes sense hope this helps and ps any copyright issues sod it if you charge for using this at least buy a pen from this website free info is hard to come by so i just thought share and share alike

 

[k.k]

excellent step by step guide to these procedures. really clear . nice one

 

[AlanWirral]

Procedure for testing
R1 + R2 METHOD 1

· Select a low resistance ohmmeter
· Check condition of instrument
· Check the meter is within calibration date
· Check the instrument is zeroed
· Check the condition of the leads and probes
· Check that the resistance of the leads and probes is nulled out
· Connect the line conductor to the protective conductor at the distribution board
· Test between line and earth terminals at each outlet in the circuit
· If there is any light switches in circuit, operate them also include strappers into test
· Record highest reading at the circuits extremity this will be R1+R2

Do you have to test at 'Each' position instead of just the last in line??

 

[AlanWirral]

Insulation resistance

Single phase

· Select a insulation resistance tester
· Check condition of instrument
· Check the meter is within calibration date
· Check the condition of the leads and probes
· Disconnect all loads
· Disconnect any sensitive equipment
· Ensure no connection between line and neutral
· Disconnect any vulnerable equipment
· Ensure all circuit breakers are on
· Ensure all light switches on
· If there is a two way lighting circuit the strappers must be brought into test
· Place temp link between line busbar(s) and neutral busbar(s)
· Set instrument to 500v d.c.
· Apply test probes to line busbar and earth
· Record result
· Disconnect temp link
· Apply test to line busbar(s) and neutral busbar(s)
· Record result




Why do you need to put a temp. link between the Line and Neutral bars when testing between line and earth?

 

[bobby101]

if you have been the installer then you will know the last or further most point in the circuit otherwise the best method would be to test all in the circuit to determine the last point in the circuit.
if you want to be picky or no common sense ( i dont mean to sound arsey ) then goto the last visual point of said circuit as a general rule.
experience is a lifelong achivement ........ as you well know " i hope the end of a radial circuit will have the highest reading" .............. no point in testing the light at the db in the hall when you have another light in the same circuit 20 or 30 mts away catch my drift.

 

[AlanWirral]

Oh I see....so the general consensus is that is that it's someone elses install and your testing it? So you should test as such?

 

[beevorm]

How about the resistence of the long lead

 

[brucelee]

hi mate
measure the resistance of your R2 lead and subtract from measured value to give you the value for recording
or if your tester has a auto null facility this should be done before measurement