OP
amberleaf
Polarity : ( Competent Person ) ( Dead Test ) Apprentice : you'll get some Q/A on 17th Edition
Polarity tests are made to verify that every fuse or single-pole device is connected in the Phase Conductor Only , ( 612.6 )
> Edison screw lampholders should be connected so that the Phase conductor is connected to the Centre contact : <
Lampholders to BS-EN 60238 . in circuits having an earthed Neutral conductor , centre contact bayonet and Edison screw lampholders have the outer or screwed contacts connected to the Neutral conductor ( 612.6 (ii)
The Tests should be Carried Out before the Installation is Energised Using a Low-Reading Ohmmeter or Continuity Test Instrument ,
Much of the Polarity Testing can be Carried Out during the process of testing CPC continuity by using the ( R1 + R2 ) method .
However Polarity should also be confirmed after connection of Supply ,
Earth Fault Loop Impedance ( External to the Installation ) ( 612.9 ) ≈ ≈ ( Live Test ) ≈ ≈ ***
The external earth fault loop impedance ( Ze ) is one of the Supply characteristics to be recorded ( Ze ) can Only be measured by testing at the Origin of the Installation . “ Before Testing “ ( The Earthing Conductor must be Disconnected from
The Main Earthing Terminal and the Entire Installation must be Isolated from the Supply ,
The purpose of Disconnecting the Earthing conductor is to ensure that measurement is not affected by Parallel Paths of , for Example :
The Main Bonding Conductors . The Instrument to be Used is an Earth Fault Loop Impedance Test Instrument :
The procedure is as follows :
* open the main switch :
* disconnect the earthing conductor :
* check test instrument and leads :
* apply test probes to the live side of the main switch and disconnected earthing connection :
* check polarity indication for correct connection :
* press the test button and record results :
* reconnect the earthing conductor must be disconnected from the main earthing terminal and the entire installation must be isolated from the supply ,
The purpose of disconnecting the earthing conductor is to ensure that measurement is not affected by Parallel Paths of , for Example .
The Main Bonding Conductors . The instrument to be used is an Earth Fault Loop Impedance test instrument ,
The procedure is as follows :
* open the main switch :
* disconnect the earthing conductor :
* check test instrument and leads :
* apply test probes to the live side of the main switch and disconnected earthing conductor :
* check polarity indication for correct connection :
* press the test button and record result :
* reconnect the earthing conductor before restoring the Supply :
Circuit Impedance Measurement :
The type of instrument to be used is the same as that used for external impedance testing , The earth loop impedance ( Zs ) of every circuit should be measured at the point furthest from the incoming Supply ,
The test must be undertaken with all protective conductors connected :
Prospective Fault Current : ( 612.11 ) ≈ ≈ ( Live Test ) ≈ ≈ ***
This is the largest current that would flow in the event of a fault between live conductors or between a live conductor and the earthing conductor . the value should only be measured at the origin of the installation .
Only the largest value is recorded The earthing conductor , main bonding conductor and CPC should all be connected .
The instrument used is an earth fault loop impedance test instrument with a prospective fault current range ,
A Polarity Check should also be made on Incoming Supply : ( PS: I don’t know if you still get this at Collage ) ≈ ≈ Live Testing , ≈ ≈
Continuity of Protective Conductors . ( 612.2.1 ) GN-3 ( Dead Test )
Main & Supplementary Equipotential Bonding :
There are Two options for Undertaking this Continuity Test : ( R1 + R2 ) method (1) or wander lead ( R2 ) only method (2)
When testing for continuity of main and Supplementary Equipotential Bonding , it is usual to apply the ( R2 ) only test ,
Before carrying out this test to confirm continuity of the appropriate bonding conductor ,
It is necessary to avoid the measurement of parallel paths ,
Accordingly: it is advisable to disconnect one end of the bonding conductor to be tested and any intermediate connections with services .
The wander lead method is undertaken by connecting one lead of the test instrument to the main earthing terminal with a long lead ,
With this long lead and the other lead of the instrument , make connection at the remote end of the bonding conductor .
Remember to Null the test leads of their instrument for this test , otherwise the measured value will include the résistance of the wander lead ,
It is also important to remember to Re-Null the test leads of the instrument only when the ( R2 ) test is completed ,
Otherwise , again the measured value would give an incorrect measurement ,
The ( R1 + R2 ) method applies to circuit protective conductors and their associated phase conductor ,
The Procedure is as follows :
* Isolate the Supply :
* Connect the phase & cpc conductors together at the distribution board :
* Measure the résistance between phase and cpc at each outlet or point :
* Measure and record the résistance between phase & cpc at the furthest point :
* Remove the temporary phase / cpc connection :
The ( R1 + R2 ) method can also be used to check the polarity of each circuit .
When testing ( R1 + R2 ) at each point it is also necessary to operate the switch in order to confirm an open circuit condition
When the switch is in the off position , therefore confirming polarity ,
Continuity of Ring Final Circuit Conductors :
Requires five distinct steps to be undertaken . The confirmation of continuity of ring final circuits
( Unfortunately some contractors appear to omit steps 2 , 3 , 4 , ) the procedures are as follows :
Step 1 : ( Checking Continuity of Live and Protective Conductors of a Ring Final Circuit ) ↔ ( little r1 & r1 : r n & r n : cpc & cpc )
Conductor Continuity
Isolate the Supply ,
Measure the résistance of the End–to–End Phase , Neutral and Circuit Protective Conductors Separately And record the values ,
The values of the Phase & Neutral conductors will indicate whether or not the conductors are continuous ,
Moreover , the Phase & Neutral conductors should have the same value of résistance .
The results taken should be recorded as ( r1 , r n & r2 , ) Schedule of Test Results include the provision for recording
Such measurements , then a ( tick ) should be entered in the column marked Ring .
Step 2a : ( Ring Final Circuit with No Spur ) Lead on Line & Neutral / Lead on Line & Neutral :
Phase-to-Neutral :
Connect the incoming Neutral to the outgoing Phase of the circuit and vice versa , Measure the résistance between the pairs
And note the results , The reading obtained should be half that obtained for either the Phase or Neutral conductor in Step 1 :
Step 2b :
Measure between Phase & Neutral at each point on the Ring Circuit .The readings should be much the same as in step ( 2a )
Sockets wired as spurs will give a slightly higher reading , Schedule of Test Results include the provision for recording
Step 3 :
Phase-to-Earth :
Repeat steps 2a & 2b but using the Phase and CPC conductors , This test also confirms polarity , The highest value obtained should be recorded in the ( R1 + R2 ) column ,
Step 4 :
Reconnect the conductors :
Insulation résistance , Before proceeding with this Test it must be ensured that all equipment vulnerable to an insulation résistance test
Has been disconnected , The Insulation is normally measured between Live conductors and Live conductors to Earth
The procedure for insulation résistance testing between Live conductors is as follows :
* Isolate the Supply :
* Disconnect all current using equipment and close all switches :
* Disconnect equipment vulnerable to a test
* Check instrument and leads :
* Select test voltage range :
* Connect the instrument and record values of Phase to Neutral between Phases , and Phases to Neutral for ( 3 Phase-Supply ) and
Between Live conductors :
Step 3 : ( Ring Final Circuits with No Spur )
Step 4 : ( Ring Final Circuits with Unintentional Spurs )
Polarity tests are made to verify that every fuse or single-pole device is connected in the Phase Conductor Only , ( 612.6 )
> Edison screw lampholders should be connected so that the Phase conductor is connected to the Centre contact : <
Lampholders to BS-EN 60238 . in circuits having an earthed Neutral conductor , centre contact bayonet and Edison screw lampholders have the outer or screwed contacts connected to the Neutral conductor ( 612.6 (ii)
The Tests should be Carried Out before the Installation is Energised Using a Low-Reading Ohmmeter or Continuity Test Instrument ,
Much of the Polarity Testing can be Carried Out during the process of testing CPC continuity by using the ( R1 + R2 ) method .
However Polarity should also be confirmed after connection of Supply ,
Earth Fault Loop Impedance ( External to the Installation ) ( 612.9 ) ≈ ≈ ( Live Test ) ≈ ≈ ***
The external earth fault loop impedance ( Ze ) is one of the Supply characteristics to be recorded ( Ze ) can Only be measured by testing at the Origin of the Installation . “ Before Testing “ ( The Earthing Conductor must be Disconnected from
The Main Earthing Terminal and the Entire Installation must be Isolated from the Supply ,
The purpose of Disconnecting the Earthing conductor is to ensure that measurement is not affected by Parallel Paths of , for Example :
The Main Bonding Conductors . The Instrument to be Used is an Earth Fault Loop Impedance Test Instrument :
The procedure is as follows :
* open the main switch :
* disconnect the earthing conductor :
* check test instrument and leads :
* apply test probes to the live side of the main switch and disconnected earthing connection :
* check polarity indication for correct connection :
* press the test button and record results :
* reconnect the earthing conductor must be disconnected from the main earthing terminal and the entire installation must be isolated from the supply ,
The purpose of disconnecting the earthing conductor is to ensure that measurement is not affected by Parallel Paths of , for Example .
The Main Bonding Conductors . The instrument to be used is an Earth Fault Loop Impedance test instrument ,
The procedure is as follows :
* open the main switch :
* disconnect the earthing conductor :
* check test instrument and leads :
* apply test probes to the live side of the main switch and disconnected earthing conductor :
* check polarity indication for correct connection :
* press the test button and record result :
* reconnect the earthing conductor before restoring the Supply :
Circuit Impedance Measurement :
The type of instrument to be used is the same as that used for external impedance testing , The earth loop impedance ( Zs ) of every circuit should be measured at the point furthest from the incoming Supply ,
The test must be undertaken with all protective conductors connected :
Prospective Fault Current : ( 612.11 ) ≈ ≈ ( Live Test ) ≈ ≈ ***
This is the largest current that would flow in the event of a fault between live conductors or between a live conductor and the earthing conductor . the value should only be measured at the origin of the installation .
Only the largest value is recorded The earthing conductor , main bonding conductor and CPC should all be connected .
The instrument used is an earth fault loop impedance test instrument with a prospective fault current range ,
A Polarity Check should also be made on Incoming Supply : ( PS: I don’t know if you still get this at Collage ) ≈ ≈ Live Testing , ≈ ≈
Continuity of Protective Conductors . ( 612.2.1 ) GN-3 ( Dead Test )
Main & Supplementary Equipotential Bonding :
There are Two options for Undertaking this Continuity Test : ( R1 + R2 ) method (1) or wander lead ( R2 ) only method (2)
When testing for continuity of main and Supplementary Equipotential Bonding , it is usual to apply the ( R2 ) only test ,
Before carrying out this test to confirm continuity of the appropriate bonding conductor ,
It is necessary to avoid the measurement of parallel paths ,
Accordingly: it is advisable to disconnect one end of the bonding conductor to be tested and any intermediate connections with services .
The wander lead method is undertaken by connecting one lead of the test instrument to the main earthing terminal with a long lead ,
With this long lead and the other lead of the instrument , make connection at the remote end of the bonding conductor .
Remember to Null the test leads of their instrument for this test , otherwise the measured value will include the résistance of the wander lead ,
It is also important to remember to Re-Null the test leads of the instrument only when the ( R2 ) test is completed ,
Otherwise , again the measured value would give an incorrect measurement ,
The ( R1 + R2 ) method applies to circuit protective conductors and their associated phase conductor ,
The Procedure is as follows :
* Isolate the Supply :
* Connect the phase & cpc conductors together at the distribution board :
* Measure the résistance between phase and cpc at each outlet or point :
* Measure and record the résistance between phase & cpc at the furthest point :
* Remove the temporary phase / cpc connection :
The ( R1 + R2 ) method can also be used to check the polarity of each circuit .
When testing ( R1 + R2 ) at each point it is also necessary to operate the switch in order to confirm an open circuit condition
When the switch is in the off position , therefore confirming polarity ,
Continuity of Ring Final Circuit Conductors :
Requires five distinct steps to be undertaken . The confirmation of continuity of ring final circuits
( Unfortunately some contractors appear to omit steps 2 , 3 , 4 , ) the procedures are as follows :
Step 1 : ( Checking Continuity of Live and Protective Conductors of a Ring Final Circuit ) ↔ ( little r1 & r1 : r n & r n : cpc & cpc )
Conductor Continuity
Isolate the Supply ,
Measure the résistance of the End–to–End Phase , Neutral and Circuit Protective Conductors Separately And record the values ,
The values of the Phase & Neutral conductors will indicate whether or not the conductors are continuous ,
Moreover , the Phase & Neutral conductors should have the same value of résistance .
The results taken should be recorded as ( r1 , r n & r2 , ) Schedule of Test Results include the provision for recording
Such measurements , then a ( tick ) should be entered in the column marked Ring .
Step 2a : ( Ring Final Circuit with No Spur ) Lead on Line & Neutral / Lead on Line & Neutral :
Phase-to-Neutral :
Connect the incoming Neutral to the outgoing Phase of the circuit and vice versa , Measure the résistance between the pairs
And note the results , The reading obtained should be half that obtained for either the Phase or Neutral conductor in Step 1 :
Step 2b :
Measure between Phase & Neutral at each point on the Ring Circuit .The readings should be much the same as in step ( 2a )
Sockets wired as spurs will give a slightly higher reading , Schedule of Test Results include the provision for recording
Step 3 :
Phase-to-Earth :
Repeat steps 2a & 2b but using the Phase and CPC conductors , This test also confirms polarity , The highest value obtained should be recorded in the ( R1 + R2 ) column ,
Step 4 :
Reconnect the conductors :
Insulation résistance , Before proceeding with this Test it must be ensured that all equipment vulnerable to an insulation résistance test
Has been disconnected , The Insulation is normally measured between Live conductors and Live conductors to Earth
The procedure for insulation résistance testing between Live conductors is as follows :
* Isolate the Supply :
* Disconnect all current using equipment and close all switches :
* Disconnect equipment vulnerable to a test
* Check instrument and leads :
* Select test voltage range :
* Connect the instrument and record values of Phase to Neutral between Phases , and Phases to Neutral for ( 3 Phase-Supply ) and
Between Live conductors :
Step 3 : ( Ring Final Circuits with No Spur )
Step 4 : ( Ring Final Circuits with Unintentional Spurs )
Last edited by a moderator: