How to Carry Out the Continuity of the CPC & Polarity Test on a Lighting Circuit Using an R1R2 Link

In this video I demonstrate how to carry out a combined continuity of the circuit protective conductor (CPC) and polarity test on a 1 way lighting circuit. To carry out this test the circuit is proven to be isolated and the main switch is locked off. I use BS 7671 On-Site Guide section 10 to illustrate the testing procedure and the position of the link within the consumer unit. The R1R2 link has a crocodile clip on one end and a magnet pozi tip on the other. By using the R1R2 link it removes the need to disconnect conductors within the consumers unit. I demonstrated with my Megger MFT tester how to remove the resistance of the leads and the R1R2 link before starting the test. This test requires a measurement at every point in circuit with the highest one recorded under the box heading R1 + R2 in ohms. The polarity element of the test is achieved by test at the lighting point and operating the switch as see full scale definition on the MFT tester. The test is then repeated at the switch to prove the circuit protective conductor is present. Of the two reading measure the highest one is recoded in the testing paperwork and a tick can be entered under the polarity box.

🕐 Time Stamps - Cut to the action 🕕

00:00 - Continuity of CPC and polarity test
00:15 - R1R2 link
00:32 - Safe isolation
00:53 - Section 10 of the On-Site Guide
01:22 - Temporary link
01:42 - Setting up my Megger MFT tester
02:28 - Removing the leads and link resistance
03:25 - Linking line and CPC in the consumer unit
04:05 - R1R2 link in place
05:00 - 3 plate method
05:37 - Leads connected in the lighting point
06:26 - Operate the switch to prove polarity
08:00 - Testing at the light switch
08:38 - Recording the results
09:02 - Is the switch further away than the light?
09:35 - Line connection
11:20 - Summary of learning

🔵 Electrical Safe Isolation Single and 3 Phase Installations

R1R2 Link Can Be Found At

Videos are training aids for City and Guilds (C and G) and EAL courses Level 1, 2, 3 plus AM2, AM2S and AM2E.

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[JURASSICDIVERUK]

Great informative video. Would be great if you did a definitive video on what tests should be done and how they are carried out when doing an EICR in a domestic property. I'm sure it will be a big wake up to some out there! 😊

[Ro-uiwo]

Learn something new everyday. Nice one mate!

[UndeadKieran]

Hi Gaz! Would you consider doing a video on selection of breakers/other circuit protective devices? It's something that was never formally covered in my apprenticeship and would be handy for others I'm sure?😀

[ZopcsakFeri]

So by "polarity", do you mean whether the switch interrupts the L or N conductors?
Sorry Gary for an additional question - and forgive me I'm a student - but would your measurement of 0.09Ω be equal to the loop impedance of the circuit?

[no_short_circuit]

Hi Gaz, thanks for the video. I'm interested in all things eletrical but I'm not a qualified sparky. In the video when nulling the leads you say that "if it was flashing zero we know it's below zero". As you're going to measure the R1+R2 in ohms (a positive value) can you explain how you can get a resistance below zero, ie a negative value or what am I missing?

[HatBoyHarvey]

What about the extra length of cpc to the switch?

[harveywakefield]

Hey Gary, just a quick one, can you explain why you test on the switch side of the cpc rather than on the loop terminals?

[MstrBujie]

Hi! I have the am2 exam in 2 weeks, my question is what about the paralel path on R1+R2, on the am2 do i need to test with cpc conected, or disconected from MET? Thanks for an eventualy answer! I realy appreciate yyour video!

[danielteyehuago]

Please i want to ask you this question; what's the right order in which you should arrange your circuit breaker in your consumer unit. should it be from the lowest breaker to the highest or highest breaker to the lowest and why... Thanks

[Mircea]

I don't remember measuring the R1+R2 at the light switch during my training a few weeks ago, only the continuity of the CPC using continuity test method 2. Very strange.

[mattreed]

Hi mate, where did you get the R1 R2 link leads from?