Earth loop impedance test

Mikeyshragh

For a Earth loop impedance test on a lighting circuit does all the bulbs on the circuit need to be taking off when doing the test. I'm doing the test from the light fitting that the at the end of the circuit. But I was wondering does the rest of the bulbs stay in or out of the circuit. Thanks

2011

Leave then in.
Think of the "loop" itself.

Mikeyshragh

2011 wrote: »

Leave then in.
Think of the "loop" itself.

Thanks a mill. I just wasn't sure.

Mikeyshragh

Hi. What is the best way to check if pipe work is bonded? There is a lot of pipe work and parts of it I don't see bonding but that's not to say it's bonded else where. Would I use a wonder lead? And if so what would be the best meter? Thanks

Mikeyshragh

Hi. I'm wondering what is the best way or easiest way to test pipe work all over a hotel for bonding. I can't see bonding on a lot of the pipe work but that is not saying it's not bonded else where. Would I test with a fly lead? If so what meter would it use ? Like a normal multi meter? Thanks

Doom

Use a fluke multi meter or similar, set it to ohms, connect to the main earth, zero the fly wire resistance, readings under 2 ohms is good

brightspark

Doom wrote: »

Use a fluke multi meter or similar, set it to ohms, connect to the main earth, zero the fly wire resistance, readings under 2 megohms is good

That makes no sense

brightspark

Mikeyshragh wrote: »

Hi. I'm wondering what is the best way or easiest way to test pipe work all over a hotel for bonding. I can't see bonding on a lot of the pipe work but that is not saying it's not bonded else where. Would I test with a fly lead? If so what meter would it use ? Like a normal multi meter? Thanks

If you don't know how to do it, you probably shouldn't be doing it!

Testing installations is now restricted works, are you a registered electrical contractor, with a qualified certifier number?

brightspark

From this and your post re.Earthing, IF you are a qualified electrician you should do the City and Guilds course below in Baldoyle.

http://www.teeu.ie/_notices/ELECTRICAL_TESTING.pdf

If you aren't then you really shouldn't be doing the work.

Mikeyshragh

brightspark wrote: »

If you don't know how to do it, you probably shouldn't be doing it!

Testing installations is now restricted works, are you a registered electrical contractor, with a qualified certifier number?

I am but haven't done this test before so I'm looking for advise. Thanks

Mikeyshragh

brightspark wrote: »

That makes no sense

Thanks for the reply. Should the meter be set at a low or high reading?

Mikeyshragh

brightspark wrote: »

From this and your post re.Earthing, IF you are a qualified electrician you should do the City and Guilds course below in Baldoyle.

http://www.teeu.ie/_notices/ELECTRICAL_TESTING.pdf

If you aren't then you really shouldn't be doing the work.

I'm waiting to do the course with RECI. I want to do these test on my own first so I have an idea when it comes to the course of what I'm doing and know what questions to ask. I know the questions are a bit stupid or I should know them. But I have to start somewhere

brightspark

Mikeyshragh wrote: »

Thanks for the reply. Should the meter be set at a low or high reading?

:eek:

If an apprentice asked that I would doubt his capability to become an electrician.

It's phase 2 level!

http://www.ecollege.ie/site/liu/electrical_notes/LL227.pdf

brightspark

Mikeyshragh wrote: »

I'm waiting to do the course with RECI. I want to do these test on my own first so I have an idea when it comes to the course of what I'm doing and know what questions to ask. I know the questions are a bit stupid or I should know them. But I have to start somewhere

If you are waiting to do the course, that must mean you are not currently certified to carry out testing.

Start somewhere? Didn't you do an apprenticeship?

Here are notes that you might find useful anyway (posted in other thread too)

http://www.ecollege.ie/site/liu/electrical_notes/LL227.pdf

2011

Doom wrote: »

Use a fluke multi meter or similar, set it to ohms, connect to the main earth, zero the fly wire resistance, readings under 2 megohms is good

2 mega ohms=2,000,000 ohms
This is a very high resistance.

With equipotential bonding a low resistance between simultaneously accessible conductive parts is what is required.

2011

There are many experienced electricians that have little or no testing experience.
The idea of a forum is that people can ask questions.

brightspark

2011 wrote: »

There are many experienced electricians that have little or no testing experience.
The idea of a forum is that people can ask questions.

Perhaps, but should professionals be asking questions in forums, where dangerously wrong answers are given?

Maybe if incorrect information was removed quickly and consistently a forum could used, but it isn't.

Also every electrician should know that a low resistance is necessary for continuity, it's basic principles, isn't it?

Mikeyshragh

2011 wrote: »

2 mega ohms=2,000,000 ohms
This is a very high resistance.

With equipotential bonding a low resistance between simultaneously accessible conductive parts is what is required.

Thanks for ur help. I need to do a few test to get better at testing. Thanks again

2011

brightspark wrote: »

Perhaps, but should professionals be asking questions in forums, where dangerously wrong answers are given?

Frequently answers provide links to verify answers, as can be seen in this thread.

Posts have been known to assist posters to think the problem through properly.

Also every electrician should know that a low resistance is necessary for continuity, it's basic principles, isn't it?

Electricians not being able to test is a problem that I see all of the time. It has been identified that training and understanding is lacking in this area. Recently an electrical testing and verifiers course has been launched to address this (as I am sure you know). Why do you think the course is only valid for a few years? Because people forget.

In addition some electrical apprentices did not received very poor instruction in the first place.

He never said he was doing up certs.
He could be just trying out the tests in his own house to get a feel for them.

brightspark

urbanledge wrote: »

He never said he was doing up certs.
He could be just trying out the tests in his own house to get a feel for them.

http://www.boards.ie/vbulletin/showthread.php?p=89307281

http://www.boards.ie/vbulletin/showthread.php?p=89338168

First thread refers to a ban marie tripping lights, possibly requiring a C rated breaker?

Second thread refers to checking the bonding in a hotel

So the testing wasn't referring to his house, also if the OP had indicated initially that he was simply studying I would not have reached the reasonable conclusion he was trying to do an actual job.

Mikeyshragh

brightspark wrote: »

http://www.boards.ie/vbulletin/showthread.php?p=89307281

http://www.boards.ie/vbulletin/showthread.php?p=89338168

First thread refers to a ban marie tripping lights, possibly requiring a C rated breaker?
Second thread refers to checking the bonding in a hotel

So the testing wasn't referring to his house, also if the OP had indicated initially that he was simply studying I would not have reached the reasonable conclusion he was trying to do an actual job.

I'm actually working in the hotel but I'm not certifying any work in it. I just want to learn how to test properly. Is that such a big deal. In these courses u are only testing off a local made up
Board on a bit of ply. It's not the same as when ur on site.

2011

The real problem that I see is when qualified/professional people don't ask questions, this applies to trades as much as to engineers. Many of them pretend to know what they are doing. The longer that this goes on for the harder it is to admit that they don't know something and as a consequence chances of an accident increases. I would far rather that people like this look for assitance ask questions and learn. I have also found that by answering questions I have learnt from it too.

When I was an apprentice (over 20 years ago) when many apprentices did "day release". One day a week they were sent to college. Frequently instructors did not even turn up, and of the ones that did some were of little use. I remember an entire class failed thier exams, shortly afterwards day release was abandoned for good. Remember at the time an electrician could fail the exams and still qualify. Many of these electricians are still around today and some of them may never have been involved in testing.

Mikeyshragh

I agree totally. How are we to learn if we don't ask questions. I know people who would be embarrassed to ask questions. Sometimes people don't know who to ask the questions?

2011 wrote: »

The real problem that I see is when qualified/professional people don't ask questions, this applies to trades as much as to engineers. Many of them pretend to know what they are doing. The longer that this goes on for the harder it is to admit that they don't know something and as a consequence chances of an accident increases. I would far rather that people like this look for assitance ask questions and learn. I have also found that by answering questions I have learnt from it too.

When I was an apprentice (over 20 years ago) when many apprentices did "day release". One day a week they were sent to college. Frequently instructors did not even turn up, and of the ones that did some were of little use. I remember an entire class failed thier exams, shortly afterwards day release was abandoned for good. Remember at the time an electrician could fail the exams and still qualify. Many of these electricians are still around today and some of them may never have been involved in testing.

Doom

brightspark wrote: »

That makes no sense

Your right.... :-/
Read the op wrong

Doom

Doom wrote: »

Use a fluke multi meter or similar, set it to ohms, connect to the main earth, zero the fly wire resistance, readings under 2 ohms is good

Ignore the above... I didn't read the op properly

brightspark

Quote:
Originally Posted by Doom
Use a fluke multi meter or similar, set it to ohms, connect to the main earth, zero the fly wire resistance, readings under 2 ohms is good
Ignore the above... I didn't read the op properly

Even 2 ohms is too high on circuits that are protected by breakers over 10A, the earth loop impedance would be too high for the breaker to operate!

I'd expect bonding using 10sq to be significantly lower.

100m of 10sq would have a resistance of about 0.176 ohms (based on table in RECI guide)

thomas83

brightspark wrote: »

Even 2 ohms is too high on circuits that are protected by breakers over 10A, the earth loop impedance would be too high for the breaker to operate!

I'd expect bonding using 10sq to be significantly lower.

100m of 10sq would have a resistance of about 0.176 ohms (based on table in RECI guide)[/

Just a quick question on loop testing if I short out L+ N at the board and then test between L and earth will this give me
Fault impedance for the socket and lighting circuits??

thomas83

thomas83 wrote: »

brightspark wrote: »

Even 2 ohms is too high on circuits that are protected by breakers over 10A, the earth loop impedance would be too high for the breaker to operate!

I'd expect bonding using 10sq to be significantly lower.

100m of 10sq would have a resistance of about 0.176 ohms (based on table in RECI guide)[/

Just a quick question on loop testing if I short out L+ N at the board and then test between L and earth will this give me
Fault impedance for the socket and lighting circuits??

Sorry I ment to say insulation resistance test there not loop test

brightspark

Yes

http://www.ecollege.ie/site/liu/electrical_notes/LL227.pdf

See pages 16 through 19 .

Note the warning about 2 way switches.

And of course all the other warnings mentioned there.