Continuity and Polarity Test

[Jupiter01]

"The above understanding is from the OSG @scousespark"
It's clear to me that you don't understand what the reasons for doing the tests are and what the results tell you, you only understand that certain tests need to be done. You need to understand WHY these tests are needed and what the results show. If you had a basic understanding of how electric circuits work, say GCSE physics level, you would be able to deduce the answers to very many of your questions yourself. This would also aid you immensely in understanding what testing is all about and why it is done in a certain way.

On a simple one-way lighting circuit with a single switch, why do you think it is necessary to to the insulation test with the switch in both positions?

To ensure that all wires are tested?
I was unclear on when you have multiple switches and hence multiple switch positions to test.

 

[davelx]

To ensure that all wires are tested?
I was unclear on when you have multiple switches and hence multiple switch positions to test.

You don't seem to have understood (read?) the question properly - it was about a simple lighting circuit with a single switch, not a circuit with multiple switches. You answered my question with a question, which indicates you were guessing.
Let me re-phrase the question:
On a simple lighting circuit with one switch, is it necessary to do the IR test with the switch in both positions? If yes, why? If no, why not?

 

[Jupiter01]

You don't seem to have understood (read?) the question properly - it was about a simple lighting circuit with a single switch, not a circuit with multiple switches. You answered my question with a question, which indicates you were guessing.
If you can answer the question correctly, with reasoning, then we can move on to the case of a more complex circuit with two or three way switching.

With a simple circuit and one switch, the switch positions ensure that all cables to and from the switch are tested as part of the IR or to confirm continuity of wires. The switch operation also confirms polarity.
That’s my understanding but again, I am still learning. Please correct me if I am wrong.

 

[davelx]

With a simple circuit and one switch, the switch positions ensure that all cables to and from the switch are tested as part of the IR or to confirm continuity of wires. The switch operation also confirms polarity.
That’s my understanding but again, I am still learning. Please correct me if I am wrong.

OK, if you do the IR test only with the switch in the on position, which cables are not being tested? (hint - Draw the circuit out)

 

[Jupiter01]

Do you need to be so patronising @davelx? I’ve shared my understanding and also acknowledged that I am still learning. Not sure what you are trying to prove…

 

[davelx]

Do you need to be so patronising @davelx? I’ve shared my understanding and also acknowledged that I am still learning. Not sure what you are trying to prove…

These questions are to guide your learning - it's a normal approach to take the student through the thought process step by step.
We are trying to help you, we gain nothing from this discussion,

 

[bernardgreen]

With three switches there are 8 possible combinations.

It would appear that eight tests need to be made to ensure all strappers are in circuit for at least one test of Insultation Resistance tests

If the way the switches are wired is known for certain then fewer tests are needed,

With switch A as shown and intermediate B set as red then strappers 1 and 2 are tested (test 1)
Change B to be set as orange then strappers 1 and 4 are tested (test 2)
Change switch A and strappers 3 and 2 are tested (test 3)

With switch C as shown the connection to the lamp is tested when strapper 2 is tested (tests 1 and 3)
If switch C is not as shown then the connection to the lamp is tested when strapper 4 is tested (test 2)

Hence instead of eight tests being needed only three tests are needed for Insulation Resistance testing on all the strappers,

 

[EFLImpudence]

Do you need to be so patronising @davelx? I’ve shared my understanding and also acknowledged that I am still learning. Not sure what you are trying to prove…

That's no way to speak to your teacher.

 

[JohnW2]

With a simple circuit and one switch, the switch positions ensure that all cables to and from the switch are tested as part of the IR ....

As has been pointed out to you, if it is a 'simple' lighting circuit, with only "1-way" switching, then if you undertaken an IR test with all switches 'on', you will have tested all of the cables.

I have no desire to be 'condescending but, as has been said (and as I've said to you a good few times before), you really need to think about (and come to understand) what you are doing, and why you are doing it, rather than relying on cookbooks/lists/menus of what needs to be done.

Kind Regards, John

 

[JohnW2]

Do you need to be so patronising @davelx? I’ve shared my understanding and also acknowledged that I am still learning. Not sure what you are trying to prove…

As davelx has said, he is asking questions in an attempt to aid your learning/understanding, and I doubt that he wants/intends to be patronising.

I am effectively doing the same in my responses to you, the only real difference being that my 'style' is somewhat different, and hence perhaps (hopefully!) less likely to appear to be 'patronising'.

However, that doesn't stop me (as others) repeatedly pointing out to you (as I very recently did) that you really do need to try to get to grips with the underlying principles. That would considerably reduce the number of questions you need to ask, and would make it much easier for you to learn, from books/people here or whatever. Although people have suggested to you things like:

Simply follow the method described in your OSG, or GN3. It describes exactly how to carry out the continuity/polarity tests on a lighting circuit.

... I personally would not advise that as your primary mode of education, since it is essentially a 'cookbook'. In my opinion, the time to look at that is after you understand what needs to be done (including why and how), since it will then help you to organise the understanding you have already gained. However, if you use it as your primary source of 'education', it will merely spoon-feed you with a list/recipe' of what needs to be done, without necessarily giving you any understanding of why you are doing it, why you are doing it in the way you do, or how to interpret the results.

Kind Regards, John

 

[scousespark]

The above understanding is from the OSG @scousespark. I’ve not plucked this out of thin air!
I am not an electrician and have had to learn this. I am asking questions where things are unclear or I require validation.

I have a local electrician that provides a certificate for my work. Yes, he will only sign it off once he can understand the design and is shown the pictures, etc. and of course, is ultimately happy with the installation. His last comment was that my work is better than most “electricians” work he has seen

On the past two occasions, his test readings have been exactly the same as what I have done on my Megger MFT. I wanted to do the same again.

The OSG tells you how to run the test. It doesn't tell you why the test is required or what readings to expect. What is the purpose of this test? Why do we link CPC to L? What readings do you expect at each lighting point? Also the IR test is different to the continuity test.

Your friendly electrician can sign off on an EIC, but you are legally obliged to follow the steps to get your work signed off by your LABC ( unless he is on the cpr and is treating you as a sub contractor to certify under his registration)

 

[scousespark]

With three switches there are 8 possible combinations.

It would appear that eight tests need to be made to ensure all strappers are in circuit for at least one test of Insultation Resistance tests

If the way the switches are wired is known for certain then fewer tests are needed,

View attachment 277307

With switch A as shown and intermediate B set as red then strappers 1 and 2 are tested (test 1)
Change B to be set as orange then strappers 1 and 4 are tested (test 2)
Change switch A and strappers 3 and 2 are tested (test 3)

With switch C as shown the connection to the lamp is tested when strapper 2 is tested (tests 1 and 3)
If switch C is not as shown then the connection to the lamp is tested when strapper 4 is tested (test 2)

Hence instead of eight tests being needed only three tests are needed for Insulation Resistance testing on all the strappers,

Jupiter only has one switch.