CONTINUITY TESTING AND INSULATION RESISTANCE TESTING - THE DIFFERENCES - THE REASONS - AND MORE

[@danielteyehuago1633]

Wow! This is video very informative and the best tutorial on the topic for me so far. I really appreciate it. Thanks for sharing it with us, Dave

[@learnelectrics4402]

Glad it was helpful. Dave.

[@Jim804]

That was a big help, thanks for explaining that Dave. The insulation resistance test actually makes sense now. I think people assume learners understand what’s going on in the conductor itself when carrying out a test. And I was not aware of the voltage used on continuity testing. I was told that the test machines use a lot of the battery life when carrying out continuity testing, esp long runs. Many Many thanks.

[@learnelectrics4402]

Thanks Jim. I suppose how much testing you do will affect battery life. My Megger had rechargeables and they needed a regular top up. The Unitest has 6 standard AA batteries and they always seem to last forever. Longer runs have more resistance so less current used, they should last longer than short runs. Dave.

[@imigrante0280]

Dear Dave.. I can say only 2 words: be blessed!

[@learnelectrics4402]

Thank you, I really appreciate those two words. Lots more to come. Dave.

[@yanalnaghawai1872]

All your videos exceeded the word of useful,,, i wish that i new about it earlier, thank you very much for everything.

[@learnelectrics4402]

Great feedback, much appreciated. Thanks for watching. Dave.

[@anthonyfindlay466]

As always Dave I appreciate the time and effort you put in to making these videos, basic knowledge is fundamental in any subject or trade, you've explained once again so thoroughly a misunderstood subject thanks again for sharing. You're a blessing 🙏cheers.

[@learnelectrics4402]

Thanks Anthony, appreciate the feedback. Dave.

[@Jaglover123]

@@learnelectrics4402 Fully agree with Anthony, I have just completed a Minor Electrical Installation course and came away quite disappointed. After watching some of your videos the penny is starting to drop and I am feeling more confident. I would be grateful if you could point me in the direction of any videos where electrics can be tested without opening the consumer unit. Also any testing equipment that is not too expensive but reliable.

[@basejumper01]

Very helpful, thank you. As an electrical installations diploma student, it helps me so much to understand the principles behind electrical testing and installation processes, why we are doing these tests and what is happening when we're doing them. This video is really clear and the diagrams help make sense of the explanations. One question though - you say with the insulation resistance test that the testing device is able to 'detect' how much charge is built up on the two conductors. How? Surely unless we get a reading of infinity, or the maximum reading of the testing device, then would it not logically mean that some amount of charge is getting through, albeit very very small, and that is enabling the testing device to return a reading of a given value, less than infinity?

[@learnelectrics4402]

How they make the testers I cannot say Michael. They have some clever boffins designing these things. Thanks for watching, appreciated,

[@user-qi8tv2sj4m]

I learnt a lot from this. Thanks mate.

[@learnelectrics4402]

Glad to hear it, appreciated, Dave.

[@three-phase562]

For the short duration insulation tests carried out using a multifunction tester, the cable size and length could affect the reading. That effect can be overcome using an extended test duration. On all the basic insulation testing that I do, the test is applied for 1 minute with the value recorded at the end, that usually gives enough time to overcome the cable capacitance and gives a more genuine insulation value for the cable.

[@learnelectrics4402]

Thanks for the input. I understand the point you make but most multi-function testers are set for a 3 or 4 second test duration and we sparkies have no control over the time period. Thanks for the support, appreciated, Dave.

[@Jo3yW]

But what extra value would these results have to anyone, that would justify eating the meter batteries up like that? Surely an IR test reading is way above the 1-2 megohms for a healthy installation, and that's all you need to know.

[@three-phase562]

@@Jo3yW If you test larger sized cabling over longer distances, then a 3 to 4 second IR test may not produce a satisfactory result, but when tested for 1 minute to overcome the cable capacitance it will be fine. In those cases, a perfectly good cable would be marked as failed. On new builds the contract may specify a required IR reading on cables greater than in the standards, so you could find the same scenario where a 3 to 4 second test shows a failure, but a 1 minute test shows a pass. If the testing is being carried out for condition monitoring rather than just go-no-go testing, then they need to be tested to a more consistent standard so that comparable results for trending can be obtained irrespective of the test apparatus used or who the test engineer is. In a domestic environment you are not likely to come across this, but on larger industrial installations, these kind of scenarios or common.

[@dg9015]

It is a massive question and thanks

[@learnelectrics4402]

Thanks for watching. Dave.

[@lucapuzzoli8363]

Hi Dave I can't thank you enough. Also I appreciate the expected reading for continuity between light or sockets circus. I notice many electrician are applying 250V before applying 500V for the IR test to find out if by accident any load may still be attached, What would be the expected reading if a load by accident would be attached to the circuit when applying 250V. Thanks A Lot have a great day!!

[@learnelectrics4402]

Thanks for the question Luca. I always test at 250V first, less chance of damaging anything and an opportunity to remove it from circuit. If its a light bulb, phone charger you will usually get 0.00 Mohms. If its a neon in an FCU it will read about 0.25 Mohms. Its just experience.

[@lucapuzzoli8363]

@@learnelectrics4402 🙏 Thank you

[@abdulmuminhalid836]

Thanks very much, more blessings

[@learnelectrics4402]

Thank you too, appreciated.

[@DunkTheHunk]

Excellent as always.

[@learnelectrics4402]

Thanks so much, appreciated.

[@darrenwardell3079]

Yet another brilliant and well explained video. One little question Dave, if i may, if you had continuity between earth and neutral, should this not show as a fail in a insulation resistance test between L+N together to earth?

[@learnelectrics4402]

It would, which is why we always put the earth back in the earth bar for IR tests. we wouldn't normally IR test with L and N connected, usually have both ends of each in free air.

[@shakilmahmud6179]

Excellent explanation

[@learnelectrics4402]

Glad it was helpful, thank you.

[@yanalnaghawai1872]

Hello,, do you have a book or CD, i can buy that include what you demonstrate in this video?

[@learnelectrics4402]

Just the videos on-line. See previous reply, go to LearnElectrics.com

[@yanalnaghawai1872]

@learnelectrics4402 Thank you for giving me the time to reply. It is highly appreciated

[@tadeuszprism2913]

Grateful ❤

[@learnelectrics4402]

Thanks for watching.

[@AJBTemplar]

Very useful and clear.

[@learnelectrics4402]

Glad to hear that, thanks.

[@rodulfomolina5584]

Great video and very informative thanks for sharing your expertise on this testing of cable procedure, I just want to ask if 10Megaohm is acceptable insulation reading for new installations, for this cable specifications: cross sectional area = (38mm.squared,THHN max V=600V )test voltage used was 1000Vdc.

[@learnelectrics4402]

The Regs expect the IR test to be above 1Megohm, though generally we look for at least 2 Mohms. Take a look at this video. Dave. kzbin.info/www/bejne/qoWWlnqBZsdjj80

[@shawnshawn911]

Thanks clear and informative indeed.

[@learnelectrics4402]

Thank you Shawn, much appreciated.

[@AhmedMohammadali-pn3ud]

very useful video thank you

[@learnelectrics4402]

You are welcome, thank you.

[@campo2309]

Thanks very much sir

[@learnelectrics4402]

Most welcome, thank you.

[@danielteyehuago1633]

Thanks for sharing it with us

[@learnelectrics4402]

Happy to do that Daniel, thanks for being here.

[@MasterTheNEC]

Greetings - Explain (as demonstrated in a different video you produced) that you connected the megohmmeter to two insulated conductors. If only (1) of the conductors insulation is damaged yet the other insulated conductor is fine. Explain how your megohmmeter gets return results when both conductors are insulated and only one is damaged.

[@learnelectrics4402]

If the insulation for the good conductor is of the correct spec, then the test will pass. The test voltage will not penetrate the good insulation.

[@MasterTheNEC]

@@learnelectrics4402 Great. However, I have "on record" the engineers for AEMC who says the undamaged conductor will magically "absorb" the return current. Mind you (3) emails before that they said their megger would not work. So, the industry is being fed BS from Manufacturers of Test Devices.

[@danielteyehuago1633]

1:02 Please can you use IR tester for continuity test, if yes how is it done.

[@learnelectrics4402]

No, the IR tester outputs 500 volts. You need to use a low ohms meter with about 4 volt output. Have a look at the video below on using a multimeter. kzbin.info/www/bejne/iGLRZXuJeLl4b6s

[@Hussain-w9k]

So for continuity tests, would you calculate the resistance first from the OS Guide tables, then test to see whether the results match from the tables?

[@learnelectrics4402]

You can do it either way. After a while you begin to know if a reading is wrong, then you can check with the tables. Thanks for watching. Dave.

[@rizgar8121]

great work

[@learnelectrics4402]

Thanks for the feedback and support. Dave.

[@ikawidya6385]

Hi, is there any standard/code regarding the continuity acceptance tes for the low resistance value? Thank you

[@learnelectrics4402]

The only one that really applies to our testing is BS EN 61557 regarding test instruments etc. Hope this helps, Dave.

[@aw5026]

hi, dave can you do some video about Contactors. thanks

[@learnelectrics4402]

Yes I can, great idea. It's now on the list. Dave.

[@aw5026]

Thanks 🙏

[@AngelaPeters-fy1tc]

Hi Dave another superb testing video. Just a we query reg the resistance table in the on site guide, it only gives the resistance of the line and cpc conductor milliohm values or r1 + r2 value and not the neutral. Is it not important to find the resistance value of neutral as well as its also a live conductor or is it only r1 + r2 we need to know as this resistance value can affect the time it takes for the fault current to disconnect the RCD in case of a fault etc. Is it not important to know the resistance value of the Rn as well for the PSCC in a table so you can refer to it during testing. I feel like this is maybe a really silly question maybe i will watch the video again.

[@learnelectrics4402]

Forget all that Angela. Yes, the tables give Line conductor and CPC, but does it matter what it is called, all you are interested in is the actual size, so choose the size of the neutral in the Line column and the cpc in the earth column, job done. Or if you want L +N, because they are the same size, just choose the same size from the line and earth columns - done. Have a look at this video I made, it answers exactly what you are asking. Dave. kzbin.info/www/bejne/jZ2UXmCkrbehg6c

[@ovieoyegwa6153]

very helpful

[@learnelectrics4402]

Glad to hear that, thank you for watching.

[@rizgar8121]

Thank you Dear, helped.

[@learnelectrics4402]

You're welcome, thank you for supporting the channel.

[@JohnDundee-el2ro]

What is the reason for main earth wire and bonding and cpcs must be connected when you do an insulation resistance test is it because if there is an earth fault you would get a shock on all the metal work when you press the 500 volts button is that dangerous or would you just jump of the pipe and be ok

[@learnelectrics4402]

You are making sure that there are no pathways from line or neutral through any exposed metalwork, metal trunking etc. If the earth was isolated, you would not be able to check this.

[@matthewdavies2421]

Fantastic job love it thank you could you do a unit on earth rods and all the main problems a good electrician would come across using a earth rod when you got time obviously

[@learnelectrics4402]

Its on the list now Matthew, thanks for the input.

[@lucapuzzoli8363]

Following ☺

[@spindoctor2646]

Can we perform an insulation resistance test with LED battens on the circuit. Many thanks

[@learnelectrics4402]

There will be transformers and voltage regulators across the circuit. These will need to be removed before testing. The transformer windings will be a dead short to the DC test voltage. And test at 250V DC, that way you will reduce the chance of damaging anything still in circuit. Thanks for watching. Dave.

[@SWGmailAdministrator]

Thanks for another great vid, great explanation as always. Would you be able to further explain why it is that a low resistance ohmmeter should have a no load voltage between 4 and 24volts and a short circuit current of no less than 200mA? This question seems to appear everywhere and yet I have no great explanation as to why other than safety. Many thanks

[@learnelectrics4402]

Good question. These parameters were set by the boffins many years ago as a way of standardising testing. it's the parameters that all meter manufacturer's work to. And yes, its a popular question in many exams. Thanks for watching, Dave.

[@tombarrett1487]

Great video, very informative for the casual interested observer. With regards to that shower, the builder would surely have used the 4mm cable for the entire length and then charge the customer accordingly? But who gets a builder to do their electrics, cheapskates, that's who. You get what you pay for I suppose.

[@learnelectrics4402]

Not all builders are bad, most want to do a good job. Thanks for the input Tom.

[@shibilkp2614]

Supperrrr

[@learnelectrics4402]

Thanks for watching. Appreciated.

[@Phantom-mk4kp]

Anyone asking that question should not be doing this.

[@learnelectrics4402]

Thanks for watching, appreciated.

[@danielteyehuago1633]

​@@learnelectrics4402Please what should be the duration of the test voltage of 500V when performing IR test