Am2 exam live testing part need some help please!

[RyanF]

Hi everyone,

My resit on my AM2 live testing is monday coming and I need some help/ gudiance on anyone who has sat theres to help me.

Confim polarity by measuring the voltage between each phase to N and each phase to earth, then phase to phase to ensure I am getting 230/400V etc.

So then, Ze test disconnect main earth and test each phase ( 3phases) to earth . Highest value record on test sheet as Ze. Then reinstate the main earth. Make sure test equipment is set to 2 test lead LOW or NO TRIP.

Zs test at db, same as ze but, the main earth is connected. Again test each phase to earth. Record highest value on the test sheet. Again, test meter on 2 test lead Low or No trip.

Then, PFC testing, set the test equipment to 2 test lead high I think it is... then measure PEFC so each phase to earth so L1- E, L2- E and L3-E. Mental note of this value.

Then same test again but PSCC so measuring each phase to neutral. So, L1-N , L2- N, L3-N. Mental note of this value.

The test equipment I am using cant measure phase to phase so. Simply take highest value and double it normally PSCC value.

Record this on test sheet as IpF.

Then cover back on db. Then the board can be fully energised/ lock off taken off. Then carry out RCD tripping times on the ring at the FURTHEST point. Record tripping times on test sheet and functional testing of the test button. Then, functional testing of all other circuits to confirm that they are working as they should be etc.

Then phase rotation ensure I am getting correct phases at the commando outlet point and the motor circuit.

Does that all sound right? If not let me know please as my resit is Monday morning!

Cheers!

 

[sevuk]

You should confirm three phase polarity at the origin with your rotation meter as well as your commando socket.

On three phase the highest fault current will be phase to phase, so to get this you would have the prospective short circuit current (phase to neutral) x 2 as a rough guide. This would be done with the Earth connected as you want the worst case scenario.

RCDs can even be tested in the DB if there is a limitation, makes sense to test them at the furthest point though if you can.

 

[RyanF]

So do you measure PFC on high setting on the test meter but, would this trip the rcd in the main board? As this exam is carried out in a workshop environment?

Also do you just test live polarity on the incoming tail side of the 3 phase DB?

 

[sevuk]

So do you measure PFC on high setting on the test meter but, would this trip the rcd in the main board? As this exam is carried out in a workshop environment?

Also do you just test live polarity on the incoming tail side of the 3 phase DB?

If you have a three phase RCD protecting the workshop boards you wouldn't be able to do a high current test after it, but if it you have the facility to test before it this is not a problem. Have they given you any guidance notes to your practical assessment?

Three phase polarity should be tested throughout the installation.

 

[RyanF]

If you have a three phase RCD protecting the workshop boards you wouldn't be able to do a high current test after it, but if it you have the facility to test before it this is not a problem. Have they given you any guidance notes to your practical assessment?

Three phase polarity should be tested throughout the installation.

I believe the workshop for the am2 exam has a 3 phase RCD protecting the workshop. So you would test everything on 2 lead low? Both pfc and ze/zs testing?

There is only two outlets which have 3 phase and thats a commando outlet and a motor outlet point. Rest are single phase outlets i.e ring final, lights, smoke alarm etc

 

[sevuk]

I believe the workshop for the am2 exam has a 3 phase RCD protecting the workshop. So you would test everything on 2 lead low? Both pfc and ze/zs testing?

There is only two outlets which have 3 phase and thats a commando outlet and a motor outlet point. Rest are single phase outlets i.e ring final, lights, smoke alarm etc

'

For exam purposes it might be beneficial to point out why you are using the calculation of the PFC x2 with the low current 3 wire test and normally you would be doing it at origin before the RCD.

I haven't heard of any testers that do a 2 wire low current test.

Just make sure you do your safe isolation to the letter and don't energise anything with the cover off or not put back together, and you should be ok.

 

[RyanF]

So doing a ze and zs test you can use a 2 lead low test? So it doesnt trip the rcd obviously. Then a 3 lead no trip test to measure pscc and pefc? That right or wrong?

The x2 rule of thumb method is because the fault current that could be generated could occur between two phases. As some test instruments wont let you measure between phases due to the high current.

Ive already passed all the safe isolation, i just simply need to do a few live tests.

 

[sevuk]

So doing a ze and zs test you can use a 2 lead low test? So it doesnt trip the rcd obviously. Then a 3 lead no trip test to measure pscc and pefc? That right or wrong?

There is no 2 lead low test as far as I'm aware, my megger only does 2 Hi and 3 Low. If you can't do it a 2 wire high test , you'll have to use the 3 lead low test.

The x2 rule of thumb method is because the fault current that could be generated could occur between two phases. As some test instruments wont let you measure between phases due to the high current.

Mostly correct, most instruments won't let you measure the PFC between Line and Line due to the voltage.

Ive already passed all the safe isolation, i just simply need to do a few live tests.

Good job, and good luck, I'm sure other guys will add to this post later.

 

[RyanF]

In the exam we have a megger mft1740 I believe so could you let me know what setting to set it to for the tests ive described?

 

[sevuk]

Left dial - L-PE Right dial - Z - it will come up as 3 Lo - if you select Z max i'll just keep the highest loop reading at the top rather than the PFC. All these settings are green

on the left you can select V in black, if you want to do a rotation test (not on MFT 1710) use Red probe L1 Green L2 and blue L3. any incorrect line sequence will display L1 L3 L2, correct will display L1 L2 L3.

search Chris Kitcher on YouTube. He uses a Megger in his videos though not always an MFT, also you'll find it good reference for what you're doing.

 

[RyanF]

Ah right Ive watched his videos hes good to watch.

So since the workshop has a rcd would that mean I would do all tests on a low setting/ 3 lead test? As in pfc, ze and zs?

 

[polo1]

Newer Meggers do have a low current, two lead test facility -

 

[RyanF]

So Im i right it thinking that since the board has a 3 phase Rcd I would have to carry out Ze, Zs, PfC test on a 3 lead low test or not? Im honestly baffled like. Some people say 3 lead, some say 2 lead.

But when I done 2 lead Hi test on Ze it tripped the rcd in the workshop. So, if I do it in 2 lead LOW ze zs test etc this wont trip the rcd?

 

[polo1]

Ryan, you can test using two or three leads on low test, just making sure that you have selected the correct setting on your tester.
Using low test prevents the RCD from tripping, but readings tend to be a bit higher than when you test using the higher test current.

 

[RyanF]

But surely if your testing line to earth of the Ze test wont this still trip the rcd due to the imbalance? So surely you would do a 3 lead test?

As in for pfc what setting would you go on and you can do a 2 lead low test on that as well? But, again wont this trip the rcd?

Some people say do it as a 3 lead test to not trip the rcd and some say do it as a two lead test which wont trip the rcd.

I just need someone to clarify the tests and the setting on the megger tester please!

 

[polo1]

Ryan, I’ve shown the correct setting on the Megger in my earlier post ( photo). The two lead low test will not trip the rcd on any of the tests you are concerned about. Honest!

 

[RyanF]

But howcome, wont there be no current down the neutral, this causing a imbalance and tripping? Just dont want to do my live tests resit and mess it up.

How would you measure pfc on that tester then?

 

[Jakegood]

I have my am2 next week. Do you know if the sy from DOL to motor is 3 core and earth.
1 Brown, 2 black, 3 grey, then earth not neutral?

 

[sevuk]

Newer Meggers do have a low current, two lead test facility -
View attachment 40813

Yes you are correct, I seem to have completely missed this.

Anyway select the right function using the arrows on the left, with the selection on the right on "Z" and it will also display the PFC. So don't worry.

 

[RyanF]

I have my am2 next week. Do you know if the sy from DOL to motor is 3 core and earth.
1 Brown, 2 black, 3 grey, then earth not neutral?

It was a 1.5mm 4 core SYcable I believe , 3 phases and earth no neutral conductor

 

[RyanF]

Yes you are correct, I seem to have completely missed this.

Anyway select the right function using the arrows on the left, with the selection on the right on "Z" and it will also display the PFC. So don't worry.

So since there is a RCD in the workshop board. But, on the am2 board its a main isolator so I would have to carry out the test on 3 test lead LOW so I dont trip the RCD? When doing Ze, Zs and Pfc tests etc...

 

[sevuk]

There's no guarantee you won't trip the RCD, so far my megger 1741 hasn't tripped any rcds, admittedly I haven't used the 2 Lo function and didn't even know it was there! I've only used the 3 wire test and 2 Hi. I think I haven't seen it because it won't come up as an option if you have all three leads connected, for instance when using the socket adaptor.

It will still display the pfc above the Zs result, as long as you select Z not Z max, no matter what version of the loop test you use. If you can you need the measurement between Line and Neutral for your x2 PFC.

I still haven't finished sorting the electrics in this house so there's no RCDs to test here (talk about the cobblers children having no shoes), I won't be able to give it a go until Monday unfortunately.

Anyone else in a position to give further advice?

 

[Jakegood]

Silly question but when doing a PSCC test you obviously put the dial on the right hand side to L/N not L/LPE.

 

[sevuk]

no option for lo tests on L/N - L/L

you would have to do the two wire test using the green probe and the red probe. Maybe it would trip the rcd if you did L/N as it's supposed to be for L - E...

I want to try it now...

 

[RyanF]

no option for lo tests on L/N - L/L

you would have to do the two wire test using the green probe and the red probe. Maybe it would trip the rcd if you did L/N as it's supposed to be for L - E...

I want to try it now...

Try it and let me know.

 

[RyanF]

no option for lo tests on L/N - L/L

you would have to do the two wire test using the green probe and the red probe. Maybe it would trip the rcd if you did L/N as it's supposed to be for L - E...

I want to try it now...

See he is measure L-PE and L-L/L-N on 3 lead Low test

 

[sevuk]

Mine doesn't do any low tests on LN LL, it's a 1741. There's a lot my tester does that I don't know about, like the inbuilt memory.

If you register for an account with megger and read the manual that might help. Also you can probably find these manuals through dealer websites.

 

[Baker1988]

Hi everyone,

My resit on my AM2 live testing is monday coming and I need some help/ gudiance on anyone who has sat theres to help me.

Confim polarity by measuring the voltage between each phase to N and each phase to earth, then phase to phase to ensure I am getting 230/400V etc.

So then, Ze test disconnect main earth and test each phase ( 3phases) to earth . Highest value record on test sheet as Ze. Then reinstate the main earth. Make sure test equipment is set to 2 test lead LOW or NO TRIP.

Zs test at db, same as ze but, the main earth is connected. Again test each phase to earth. Record highest value on the test sheet. Again, test meter on 2 test lead Low or No trip.

Then, PFC testing, set the test equipment to 2 test lead high I think it is... then measure PEFC so each phase to earth so L1- E, L2- E and L3-E. Mental note of this value.

Then same test again but PSCC so measuring each phase to neutral. So, L1-N , L2- N, L3-N. Mental note of this value.

The test equipment I am using cant measure phase to phase so. Simply take highest value and double it normally PSCC value.

Record this on test sheet as IpF.

Then cover back on db. Then the board can be fully energised/ lock off taken off. Then carry out RCD tripping times on the ring at the FURTHEST point. Record tripping times on test sheet and functional testing of the test button. Then, functional testing of all other circuits to confirm that they are working as they should be etc.

Then phase rotation ensure I am getting correct phases at the commando outlet point and the motor circuit.

Does that all sound right? If not let me know please as my resit is Monday morning!

Cheers!

Highlighted in the red above you say from the Zs/Zdb to get the ipf you go straight to the rcd testing this is not correct as you need to do the circuit Zs on thecircuits you dont have to takeapart to do this (all ones you have to expose live parts on canbe calculated) like the socketcircuit you have to do a Zs ateach socket and then do the rcd test but in the regs it is statedto do it with no load at theclosest socket to the rcd not the furthest.

And as for the 2 lead vs 3 leadon the testers it is totallypersonal preference as the tester can do low current 2 lead and 3 lead testing so its up to you which you choose justmake sure you have set it tolow current and not high current.

 

[Baker1988]

But surely if your testing line to earth of the Ze test wont this still trip the rcd due to the imbalance? So surely you would do a 3 lead test?

As in for pfc what setting would you go on and you can do a 2 lead low test on that as well? But, again wont this trip the rcd?

Some people say do it as a 3 lead test to not trip the rcd and some say do it as a two lead test which wont trip the rcd.

I just need someone to clarify the tests and the setting on the megger tester please!

The whole point in the low current setting is that it will use less current than the 30mA that is required to make the rcd operate so no matter what test you are doing if you set it to low setting it will use about 15mA so wont make any rcd operate. If you test between the PSCC that is between L&N so the rcd won't operate any way as the rcd will only operate on a earth fault not a short circuit.

As for the pfc you test the pefc with either 2 lead on low setting line and earth or 3 lead on low setting standard line, neutral and earth then when you test the pscc you keep it on the exact same setting and if you are useing the 2 lead method you basically move the lead from the earth to the neutral or if useing the 3 lead method you move the earth lead onto the same spot as the neutral either by putting the lead on the neutral lead (as you can normally connect them) or turn the main isolator on and put the earth lead on the neutral bar but you would not be allowed to do this way on the AM2 as you cant turn it of wothout the board cover on so just usr the 2 lead method. Obviously as its 3 phase you would do these tests between all 3 phases.

 

[Jakegood]

Obviously you would take the lead out of earth and put it in nuetral when doing PSCC on 2 lead test. And change the dial on left to L/N?

 

[Toneyz]

Ryan,
Which Megger MFT are you using? as you should be able to download from Megger user instructions so you can be sure what the tester can do.

 

[Toneyz]

Ryan,
Which Megger MFT are you using? as you should be able to download from Megger user instructions so you can be sure what the tester can do.Did you attend a course prior to being booked for the test?

 

[RyanF]

Ryan,
Which Megger MFT are you using? as you should be able to download from Megger user instructions so you can be sure what the tester can do.

I think of the top of my head its a Megger MFT1730 or 1740. Ive been explain how to use it but, kind of forgot what them settings where as in the workplace I use a different tester with different settings alltogether.

 

[Toneyz]

I think of the top of my head its a Megger MFT1730 or 1740. Ive been explain how to use it but, kind of forgot what them settings where as in the workplace I use a different tester with different settings alltogether.

I quite understand that as it takes a bit of time of getting used to a tester what it can do. My fundamental question to you is that have you undertook a learning course prior to this test?

 

[RyanF]

I quite understand that as it takes a bit of time of getting used to a tester what it can do. My fundamental question to you is that have you undertook a learning course prior to this test?

I done a refreshers course just before my am2 exam but, they just told us to watch videos on the tester. Which I did do before the exam and in the exam I had to ask again for clarifcation on how the megger tester works etc.

 

[Toneyz]

I wish you all the best of luck with the retest but I am very concerned regarding the questions that you are asking at this stage and the impression of the teaching given to you unless you have just paid to do the test on the day.

 

[Tes369]

I like watching this guy he makes sense I know he's not doing... AM2 but he does some good videos.

Cheers

 

[RyanF]

I like watching this guy he makes sense I know he's not doing... AM2 but he does some good videos.

Cheers

Ive just been watching his videos as well. Very good to watch with usefull tips and hints etc.

 

[Tes369]

Yeah I watched the video of him testing flats earlier that some cowboys wired what a mess

 

[Pete999]

I quite understand that as it takes a bit of time of getting used to a tester what it can do. My fundamental question to you is that have you undertook a learning course prior to this test?

undertaken!!!!

 

[RyanF]

Yeah I watched the video of him testing flats earlier that some cowboys wired what a mess

I watched it as well that was the flats in whitleybay proper shocking when I watched it like... deffo cowboy electricians...

 

[Pete999]

I watched it as well that was the flats in whitleybay proper shocking when I watched it like... deffo cowboy electricians...

Anyone got a link for the said video?

 

[Tes369]

Any trainee or apprentice won't go far wrong watching some of this lads vids.

Subscribe to this guy ....

Worthy of a thread of good practice makes a change to all the rubbish on YouTube.

Cheers

 

[Toneyz]

Anyone got a link for the said video?

Go to youtube for sparkyninger, as above Pete.

 

[Pete999]

Go to youtube for sparkyninger, as above Pete.

Tried that Ant no joy, do you mean Sparky Ninja?

 

[Tes369]

It's the video link I've posted above.

(Initial verication testing someone else's crap work.)

Cheers

 

[Tes369]

It's the video link I've posted above.

- (Initial verication testing someone else's crap work)

Cheers