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The official method is to calculate any Zs because it is considered to be more accurate. IE it does not include parallel paths. If there is an RCD upstream, the test current is lowered, which means the result is not as accurate. When carrying out a "live" Zs test on a ring, you no longer have the "figure of Eight" cross-connection, so the readings will change as you measure at each socket. To summarise, the best way is to calculate Zs by adding R1+ R2 to the Ze. We also need to take into account the Electricity at Work Regulation 14 which states that you only work live when there is no alternative. Hope that helps. All the best for the AM2! SAM

I have my am2 tomorrow, am I right in saying we only measure Zs for the ring and calculate the other readings because it’s a live test and we aren’t supposed to remove switches etc. whilst live?

Great thank you

This was helpful thank you .. i understand the cover shouldnt be off but that is obvious main concept was to prove isolation and how to do it

Yes, that is correct. The Ze is the impedance at the board, but only if DB is at origin. The boards in the training establishment will include the internal wiring in the building, so are in fact a Zdb. An estimate of Pfc between two phases, is the highest current measured between phases and neutral and multiplied by 1.732 or root 3. To estimate the current if all three phases and neutral came together would be double the current between phase and neutral. Hope that helps, and do get in touch if you need further? Thanks for the question and happy testing.

Good Vid thank you. Am I right in saying that at this distribution board the Ze is actually the Zdb and when advising about the current generally the x 1.73 is the fault for 2 phases and the x 2 is for short between all three phases ? please advise.

couldnt follow. key now stuck up bum

Quick and simple explanation thanks.

YOU SHOULD BE BANNED. TEACHING BARE HANDS within inches of 3 phase terminals AND EXPOSING 'CROSS CHEST SHOCK HAZARD. YOU NEED TO BE REMOVED FROM TEACHING ANYONE.

Very handy!

The book suggests testing Phase to neutral(single-phase) and doubling the result to obtain a 3-phase value. Since making the video, I have started also measuring the Phase to earth which as you say, could be a higher reading as it is likely to include parallel paths. In other words, you are proceeding exactly as you would with a single-phase installation but doing 3 tests; one for each phase. This is useful if you have a single-phase board fed from the three-phase board. If this is the case, you would have all the info needed for PFC on the single-phase board, and for the three-phase PFC, you simply double the highest result. Let me know if you need further.

Could someone please put me right, I thought that the test carried out was not the the PFC as he only tested phase to neutral and not phase to earth which may have given a higher fault current which then would have been the PFC, it showed on the meter that only 2 probes was in use which was the line and neutral test probes, I do stand to be corrected.

Dear Sir, the one-phase or three-phase isolation procedure (sequence) should be in more detail, this process you are explaining should be for everyone , you should explain the sequence of testing like Broun and Black, Broun and Grey, Black and grey, or L1 and L2, L2 and L3, L2 and L3, this very important for the beginners, and I hop you accept my comment.

Wait do we lock off first? I thought we do that at the end once we proved it was isolated?

Great VT.. coming to do my 2391 in June with you guys

Breakers off? Shouldn’t they be left on

Out of interest what was the size of the breakers to compare the pfc calculations against? Otherwise a faultless video.

Dont use 500v in real life, it will fry up electrical equipment in a domestic home including loads and stuff, use 250v then do calculation as if it was a 500v test. This way you dont need to remove light bulbs and stuff

Sir please send your whatsapp number

Thank you!

Thankyou sir ,wonderful

Thank You your video make me confident to do Ze/PFC testing .

Do you have Todo it in the board or can you do it in any socket in the ring circuit?

Title is a bit misleading, I was hoping to see the test of a Radial circuit, not a Ring Final Circuit.

Thanks very much I learn more from visual revision than I do the books so this was very helpful.

Thanks

Thanks for explaining it well

Great but switch off and lock-off first and always prove that your tester is working before and after use if not it might be faulty.

Maybe the ze would of been within .35 if you had nulled your leads 🤦🏻‍♂️🤣

Not good example to start with the cover off at least turn off first

What happens when the target figure is not met but connection are correct.r1.rn crossed?

Should show switching on meter

Always some teachers that can explain processes behind the subject better than others.

Thanks for the video but shouldn't you have tested your testing equipment before estarting ? What if you tester was faulty ? 🤔🤔

DONT AGREE. Measuring phase to neutral shortcircuit is not going to give you three phase PFC even if you multiply by 1.73 or 2. You better have a look at schneider cahier technique 158 and compare the formulas for all shortcircuit types. you will see that you need to measure between two phases and multiply x1.16. Many mft meters support measuring between phases even if you select L-N test. For example fluke 1654B. The only place you could do that aprox x2 times (no x1,73) is subject to the neutral being the same size and length as the live, all the way upstream and if you are far away fron the transformer so the transformer windong impedance is much smaller than the cable. Things that you will never be 100% sure. Hope this comment helps you. And if you dont believe what i said and dont know how to check, think about it. If it was so easy as doubling it up you would get that info from the meter when you are doing LN tests.

Sorry no explanation of why the readings differ? No mention of Max Zs to prove readings are suitable? No mention in fact relating to disconnection times?

Thanks for this, but you need to show how to set the meter, and would be better using a more common megger

Thank you for this Video My question is if this test is Carried out for main low voltage panel with 2500 A breaker , so the main breaker should be off ? Right ?? And we will measure for the incoming point of the breaker which is live ? We did this as a safety procedure or just to take the exact reading for pfc and ze ?

Hi thanks for the Video. Can you tell me please why you had the Main Breaker turned off when doing your PSCC test? surely the main switch and breakers should be on ?

It was better if you show what you change the function on the meter to? Thank you

Great video

Thank you

I couldn't see what you were probing on to, in order to conduct the test and you didn't tell the viewer... ! Terrible video and a poor choice of cameraman.

Do some more videos I watch alot of videos and your presentation is very good

Could you please answer my question below to clear up the confusion for me which is why do you not get zero ohms between neutral and earth in the consumer unit if the neutral is ultimately connected to earth back at the supply transformer?

Further explanation on how parallel paths lower impedance and raises the PFC would be great thanks

Excellent instruction but I have one question: The star side of a delta/star supply transformer has the neutral connected to the central point of the star which is earthed so why would you not show zero ohms from neutral to earth, or am I missing something? Thanks

Sir, that's a very good video, but I wish to know , how to select the applied voltage for single and 3 phase conductors. Is it that the the voltage applied must be twice the RMS value of nominal operatinal voltage??? Kindly reply

What is the maximum ze we should not exceed

I watched all your videos