Continuity of CPC and Polarity of our 1 Way Lighting Circuit (R1 + R2 Measured in Ohms)
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- เผยแพร่เมื่อ 5 พ.ค. 2024
- Students training aid for testing continuity of the CPC and polarity of a simple 1 way lighting circuit. Full demonstration using a MFT Megger tester set on the ohms scale, linking the line and CPC of the circuit under test and then testing at every point in the radial lighting circuit. Of all the reading we take in ohms we record the highest reading in our test paperwork under the box heading R1 + R2 continuity of CPC. We also complete the polarity test and leave the switch in the on position ready for the insulation resistance test.
== 🕐 Time Stamps - Cut to the action 🕕 ==
00:00 - Continuity of CPC
00:41 - Testing for continuity of the CPC and polarity of our lighting circuit
01:26 - Longer circuits offer more resistance
01:42 - Setting up our Megger MFT to the ohms scale
03:08 - Linking the line conductor to the CPC
04:00 - Testing at our lighting point
05:26 - Testing at our one way light switch
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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Precise and crystal clear tutorial. Your delivery is so easy to understand. Thanks for the knowledge. All the best
Thanks Gavin. I am glad my videos are helpful. All the best Gaz 👍
Brilliant videos, just started on my level 2 and this is fantastic help. Clear and precise.
Everything little detail has been shown on camera. Great video!
The re iteration of the same point is so helpful...thank you
Big thanks for taking the time to make and post your brilliant videos. Your explanations and demonstrations are crystal clear and super concise. I have my NICEIC assessment coming up soon, so your videos are invaluable for keeping everything fresh in my mind, especially as I was out of the game for quite a while and I don't do electrics every day. I updated my previous C&G Electrical Installation qualifications from way back (16th Edition), earlier this year, but the old grey matter is not as sharp as it was, hence my revisiting your top drawer tutorials whenever I get the jitters.
Stevan Stacey happy they have helped 👍
been watching these tutorials as ive got my level 2 practical exam soon and testing has never seemed easier to me
I only wish I could been thought by yourself! Th way you teach is second to none! Thank you 🙏
Massive thanks I appreciate your great comment 👍🏻
Very good at your tutorials, I'm doing my level 3 at the moment and your clips really helped. Thank you
Thanks and all the best with you course 👍. Gaz
Very helpful, thank you so much .John
Great video Gaz and his pal
Easy to understand, like the recap section.
Mahmud Choudhury thanks 🦾
This video was very useful. I'm a new learner and joined a c and g 2365 course. I have nonclue about the tetsing and the terminologies but your videos are very informative and encouraging
Thanks for the support and commenting. Good luck with your 2365 👍🏻
Very clear videos. I am learning a lot. Still valid a few years after they were made.
👍🏻
Thanks for sharing it with us
Thanks for watching and commenting 👍🏻
You are SO good at explaining Gaz
Massive thanks 👍🏻
Thank you
Great video thanks !
Thanks for the support 👍🏻
Hi guys, love the videos! Am I right in thinking that a continuity test on a DMM is different to the same test on an MFT?
I’ve seen recently some MFTs offering a 15ma or a 200ma continuity test, you don’t get that option, that I know of on a DMM, would you be able to explain what’s going on? Many thanks 😊
Can we see some testing done on an the old type B fuse boards.
Hi..... Search though I may....I cannot discover where you hold your courses / classes.
Will you tell us ? is there a choice of coursess etc...?
nice vdeo
Please do a video where you doing the same test for multiple lights . Other than that superb vid thumbs up again !
2 Plate Method Testing 2 Way Switching for Continuity of CPC, Polarity and Insulation Resistance
th-cam.com/video/P-D6chUrRNk/w-d-xo.html
Thanks
👍🏻
Hi
You mentioned that if 0.00 are flashing it’s below 0.00
So I’m testing cooker circuit 6mm t&e linked at cu with crocodile clips
At the cooker switch I’m getting flashing 0.00
Does it mean I have problems with my tester ?
Thanks
The board you used is Osb board. I really like it and want to buy one. Can you send me a link of it please.
Hi GSH.
What is the actual reading we are looking for, in Lehman’s terms what is the threshold for the CPC / line readings for continuity.
And what is considered a bad reading
Hopefully Someone can give me a hand. Today i was testing r1 rn and r2. Rn and r2 results were fine. But r1 im having problems. As im getting 208 ohms! The tester is not faulty as everything else i tested was great. How do i troubleshoot this, its all relatively a new installation
Hi Gaz when you mention the switching line am I correct in thinking that that would be the live wire that feeds the switch. It connected to feed in and feed out of main circuit on the triple brass bar
Hi. I think I understand what your saying (yes) Gaz
GSH Electrical thank u again for your help
When you’re testing at the switch are you testing between permanent live and cpc or switch live and cpc? Thanks
I am picking up the closed part of the circuit and the cpc to prove the cpc is at the switch.
I'm doing my practical assessment and went on the shorter to watch this because I can't remember for my life how to do this
😁👍
What if you can’t reach the switch whilst testing the lamp fitting…Is it ok to just test the polarity at the switch?
Gaz can you explain why we should test at each lighting point and then at each switch this seems daft. Surely if the earth comes from the CU to the light then to the switch then testing it the switch will confirm that the earth conductor is continuous, this would apply to each switch unless the earth conductor isn’t connected at the switch as you know some plastic back box’s don’t have a n ear lug . This is why I have seen some sparks were the switch is service mounted on plastic back box they dispense with the earth at the switch altogether but do contact the earth at the rose. Personally I don’t see the need to touch the rose for this test when you can just test at the switch. Also what if you are working in a stately home were the ceilings and the crystal chandelier is so high there no way of getting to it ?
Hello. What is the maximum (in ohms) allowed value for R1+R2? Thank you
3 ohms
How would you test at every light when it's not possible to get to em or a lot of downlights in a circuit or whatever would you use the lightmate adapter thing
+Roy Kirkham
Hi great question. Thinks safety first remember College is different to best practice in the real world... lots of insulated down lights I would test at the switch in each room because that could be changed to an exposed conductive part (metal). As well as trying to do the last spot light in each room. I still would want to measure the R1 + R2 at the last lighting point as well as all metal fittings that require an earth. Thanks GSH Electrical
GSH Electrical
Thanks for reply
So say you had a Cpc missing mid circuit and then tested the last light in a room what would the tester read or expected results be to tell you a Cpc was missing
Roy Kirkham
Hi if the CPC is broken mid-point of a radial circuit then no R1 + R2 would be recorded after that point in circuit so no continuity of CPC. All the best and sorry for the delay GSH Electrical
Do all lighting loads have to be removed in the house for L-E resistance test or just the light point load on circuit your testing ?
If in this case I am only testing the lighting circuit then all loads on that circuit and not other loads in the installation 👍🏻. Thanks for commenting and watching. Gaz
@@GSHElectrical Thanks. That makes sense to avoid any parallel paths through the lights to neutral and back to earth via the cut out..
Does the crocodile clip wire need to be thick/bigger in order to get a correct reading?
No just zero it out at the same time you do the test leads. Gaz 👍
@@GSHElectrical cheers buddy nice one👍
If you had more than one light would you of had to remove the CPC from the earth terminal?
If you want to remove parallel Earth path‘s then remove the CPC for the earth bar 👍🏻… in this can we only have one CPC in circuit
Would the cpc need to be removed from the earth bar before testing if other cpc conductors were attached (as in a real life situation) in order to avoid parallel paths or other interference in the testing process? Thanks
atlantic star short answer is no. I do have videos on the channel talking about parallel Earth path’s if you want to check them out 👍. Thanks for the message. Gaz
th-cam.com/video/r94dJ7ASRTY/w-d-xo.html
That was helpful. I think I get it now, there's no loop for the other cpc's, so no parallel paths. But bonding conductors would need to be removed either at the MET, or at the fitting itself e.g. water heater or metal conduit, in order to avoid pp's showing up on the reading.
@@GSHElectrical I don't agree with you. You're verifying the continuity of the CPC. If you don't take consideration of parallel paths you can't be sure of what you're testing. I.e. is that the r1r2 of the immersion circuit or is is the R1+r(resistance of pipework back through heating circuit and main protective bonding?). This is why we don't calculate R1+R2 from zs but we can calculate zs from ze+R1+R2. I know what the pictures show in GN3... I think it's wrong and they repeatedly draw attention to parallel paths.
Hi Gaz, I think I'm going bonkers because I've never seen an Rn test done on the lighting circuit....the cable from the lamp back to the consumer unit .
Hi. The only real time you would test the neutral on a lighting circuit is during fault finding. If a tested lighting circuit doesn’t work it’s probably the lamp failed or an issue with the neutral. Thanks for commenting Gaz
@@GSHElectrical thanks for the prompt reply, really love your channel btw !
I'm from India thank-you sir
Sreeraj AM I’m not from India, thank you!
i guess this is usefull for UK electricians or fault finding not much use of this
Hi. What is the maximum acceptable figure for continuity before further investigation is needed. Like insulation resistant it is 1 Mohm min, 2 Mohm Investigate further, 20Mohm for new install. I don't think I've ever seen anything regarding continuity. I have had figures from 0.37 upto 9 ohms in the same house. OSG I1 pg 196 has it per meter but what if you don't know length dues to it being in the wall. Sorry if I'm being thick.
It depends on lots of factor and when you start learning about the earth fault loop impedance the measured values of R1 and R2 will drop in place 👍🏻
Earth Fault Loop Path for a TN-S Earthing Arrangement & Formula For Total Earth Fault Loop Impedance th-cam.com/video/24Yjts1817E/w-d-xo.html
@@GSHElectrical so In theory the continuity is just a case of lower the better and near to zero as possible. It only becomes an issue if the Zs figures are out from table B6. Then I assume you would investigate cause and Possible change breaker or cable to reduce impedance.
Hi Gaz great video, for the purposes of my G&G level 2 practical exam is it ok to link between my line and earth bar even if there are other circuits connected to the earth bar? Regards Alex
Easy answer YES. Thanks for watching and good luck. Gaz 👍
GSH Electrical thanks a lot! 👍
Hi.. How can I become a domestic installer that can test and certify my own wiring.. Thank you
Hi. I am just in from a 15 hour day so sorry for the delay. My adults do a level 2 diploma over one year then they do a level 3 certificate in installing, testing and ensuring compliance of electrical installation in dwellings over 2 years so they can become a domestic installer (our courses are EAL but City and Guilds do them as well). Hope this helps and thanks for watching GSH Electrical
GSH Electrical thank you very much you are great
I have my level 3 synoptic for inspection and testing on the 11th and I've only had half a day with one meter between 17 or so students........wish me luck 😂😂😭
I wish u all the luck in the world 👍🏻
@@GSHElectrical on the plus side, the college will struggle to hide it if we all fail the course since quite a few are considering contacting C&G over the way the college has handled things so hopefully we'll be the last group to fail there if we do.
I can totally empathise.
@@Jonnyturboable thankfully I did pass in the end
Where’s the link
Can’t find it
What's the difference between R1+R2 test and a ZS test ?
One is a dead test and one is a live test
You mentioned in the first part of the video that there (could be) several circuits in a lighting system and although you are are working on a single circuit which is fine for the video..... back to several circuits, these could have live crossed circuits at the switch bank due to human error.....you did not check that the line wire was dead before linking it to ground!
Hi could you suggest a couple of testers suitable for someone embarking on the journey to become registered domestic installer many thanks
Hi. I like the megger MFT testers that I use in all my videos on testing. Try ebay for slightly older version at a great price. Gaz
hello i have three questions to ask.
i have a 20a radial circuit with 12 sockets on. from a junction box i have an fcu with a 13a fuse, which then feeds 25m of armoured cable to a shed.
1. would i do an r1 and r2 at the shed as well, which is has 4sockets and 2 fcu for heater(5a fuse) and floodlight(3a fuse)? as i believe this would be the highest reading.
2.would i also do a zs at the shed, but as it has long length, zs could be quite high, however it is protected by a 13a fuse.
3.and lastly is there a maximum value allowance for r1+r2?
thanks in advance
Hello mate if you had 100 down lights and good amount of swiches in a large domestic house, your telling me you would test every lighting point and switch in that house with the average fee your paid for an EICR IN THE REAL WORLd, as per your video
What's polarity???
And how comes u didn't test the continuity of the Neutral cable?
Thanks for watching and commenting 👍🏻
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