All your videos have been instrumental in getting me through my 2365 level 3 - i've no doubt they will be of great value for my 2391-52 next week, thank you Gaz, your time and effort in making these videos is very much appreciated !!!
Great video. Love the attention giving on when to select the 2 hi, 2lo, 3lo setting on the device. Probably the best video I have seen for this so far.
Spot on and well explained as always. Good work Gary. Going to do my 2391-52 from tomorrow. Wish me luck. I am sure I will remember your videos. Thank you.
The nice thing you said in the end of this video. I hope this video some help to be honest it was hugely helpful not some help .thank you so much you are the best teacher I see him ever.
Reg 542-04-02 "The means os earthing must be disconnected from the installation earthed equipotential bonding for the duration of the test to remove parallel paths. This is to prove that the installation has a main earth. IET. Guidance note 3
Hi. Correct and I disconnect from the MET the protective bonding conductor disconnecting it from the main earthing conductor in this video. Thanks for watching GSH Electrical
@@skamuk1 would that be not for the other tests mentioned, not the max PFC demonstrated here? I didn't see mention of the installation earthing being disconnected but he says in this reply that he did that though which is confusing me as it doesn't look disconnected.
Hi, thanks for the video I’ve got my AM2 soon and it’s going to be 3P+N main switch. Carrying out this test I would crocodile clip onto the earth bar One probe in neutral One probe testing between L1,L2,L3 taking the highest reading and X by 2. Is this correct? Also what setting would it be on as on a single phase board you switch between the 2?
Just to clarify, we dont measure the fault current, we measure resistance and the tester auto calculates it and shows it as result. You dont send 4-5-600A trough your tester.
Great clear and concise videos. With your PFC test on CU main switch at considerably less than the 33Ka of the incomer, under what conditions would you expect there to be any real chance of PFC across breakers to be greater than there 6Ka max? Thanks
It’s only to test the main fuse if you test on the supply side. If you test on the load side you’ll be testing the mcb/rcbo fault current is under 6ka.
Hi In psc test why do you put red wire on neutral main isolated why mix the wire. And earth wire which is acting as neutral Went on line. Main idolater Thank you
Hi, is this one of the tests that you have to take when doing the level 2 diploma in electrical installations? Or is this for the level 3 diploma? Thanks.
Hi Gary can you please tell me how this is done using the kewtech kt62 multifunction tester or the ROBIN kts 1620 MFT as the instruction book says nothing about the two lead high loop test, on the control dial there are two settings, loop 20 ohms 200 ohms and 2000 ohms, psc 200A 2000A and 20ka also how to do Ze Another great video thank you
Hi, just a quick one I’m slightly confused with this test and I’ve my am2 on Monday. What’s confusing me is I’ve seen/heard that you have to times your highest result by x2 and that’s your ipf your record down
Testing for External Earth Fault Loop Impedance (Ze) When You Have a Main Earthing Terminal (MET) ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-nz3scSSg3ZU.html
Hi. Congratulations for the videos. Please, if you are so kind, two questions: What is the reason for the difference between the measured PFCs of the two switches, being in the same point of the installation? In the case of Line-PE [424-312A] and in the case of Line-Neutral [311-332A]. Would the measures be different with all the charges connected? Thanks
Hi. Normal practice is to measure PFC (PSCC and PEFC) only once. If the reading was less that the PFC of the smallest rating device in this case the circuit breakers 6KA then your sorted. I did it twice as a demonstration as this links to my class lessons on PFC. You have to do both PSCC and PEFC as PEFC picks up the parallel earth paths offered by extraneous conductive part (metal water pipe, metal gas pipe, metal frame of the building etc.) thanks for commenting and watching GSH Electrical
Why would you get a significantly higher Pfc L to PE vs L to N. Since you are testing a TNCS supply you would expect the same result since parallel paths are open to both tests through the MET. Or a slightly higher for Pfc might be expected for L to N, since the L tail is 25mm as opposed to 16mm earth tail. Also why test Pfc at top of breaker, as it cannot be higher than Pfc at main switch. This just encourages learners to follow a list of instructions with no awareness of what they are physically testing nor the meaning of what the results actually tell them.
Hi Gary, am struggling to understand this. Your main incoming fuse is rated at 100 amps but you’re mentioning KA. The same with the breaker, this is a 6 amp breaker but you’re now saying it’s 6KA? Can you explain further, please?
Hi. The breaking capacity is the amount of current under fault conditions the over current protective device (fuse) can handle... so commonly a 6 amp MCB can withstand fault currents up to 6000 amps (6KA). At this value and below the device can break the circuit.... over this value it can say cause a massive arc that leads to a fire or melt across the device and then not disconnect the circuit... all the best and thanks for commenting Gaz
Gary, could you tell me why on. TNS system sometimes the Pefc and the Pscc readings are different when both the eart and neutral are essentially the same conductor and both test carried out with bonding in place so same parallel paths etc? Thanks.
Hi...wWhat do you have to say regarding these two comments I read on another channel...where the tester / instructor stated the fault currents wer 370 and 350 A for PFC PSCC 1. The breaking capacity of the main fuse will need to be lower than the PFC The second commentor agreed..... 2.Exactly! How is it that having CBs of 6,000 A breaking capacity will protect a circuit with both earth fault and short circuit PSFC and PSCC of 370 A and 350A, respectively?! The whole purpose of a protective devise is to trip before a circuit or any relevant point of the electrical installation reaches its maxumum PSCC or PFC!!! If that installation has in place those protective devises then surely the PFC and the PSCC are higher than 6,000 A. I seriously suggest this video should be withdrawn. It represents a hazard in itself! It will certainly confuse the inexperienced student. Your comment would be appreciated... I think the commentors have mis-understood which part of BS7671 we are compairing...and this may need explaining...by someone somewhere. .
Hi. Thanks for the detailed message. The information you have provided me is worrying but I haven’t seen the video yet. I am not sure how you can go about having a RU-vid video removed it maybe worth highlighting these points to the channel that produced the video. Many thanks for your time GSH Electrical
The video seems fine as he did the same as yourself tested the board to ensure the fuses/circuit breakers were able to withstand the potential fault currents. It was the commentators who had it wrong....but they did raise an interesting point...in that you would expect the fuse or circuit breaker to trip with the lowest fault current...in order to save the installation.....seems odd to have a large fault current circulating and the prospective faults becomming actual faults and no breaker has tripped....was their slant on things, confusing the actual tripping current eg, 30mA or 150mA, of the device with it's actual handling capacity.
@6:03 you tested line and neutral on a high reading then switched to low reading when testing live and earth, because there's a rccb in the circuit but @6:03 isn't the rccb in the circuit aswel? Can you explain why High reading when live and neutral then low reading for live and earth please thank you
RCDs detect an unbalanced current between the L and N conductors on the outgoing side of the breaker. If the impedance test is done across the L and N terminals there is no imbalance, they are sharing the same amount of current during the test and will not trip. When doing the test between L and E, the RCD detects that the L terminal has current flowing during the test but the N terminal doesn’t, this imbalance will cause it to trip if done on the Hi setting.
Hi Gary, how is it gonna clear any faults or short circuits if the current is way below the 6KA or 33KA? I know these are breaking capacity, hence it gives safety to the installation or equipments but how is it gonna rectify the faults? thanks
The terminology is confusing it won't clear faults. (They'll be rectified physically) It has to be able to withstand them at maximum so by doing pssc and pfc we know the maximum then we simply look at the Icn of the fuse and we know it can close a circuit if a fault occurs. If for example he found 11ka pfc and only 6ka Icn if a fault occurs they may not isolate the supply.
Could you please explain to me why when we do a zs on a circuit on an mcb we get different readings when doing a 2 high and 2 low test? I don't understand why the readings are so different. And surely if you are getting a high test result on the 2 low setting you can put it on 2 high setting and get a much lower reading. If you have any info on the megger high/low settings it would be much appreciated 👍
@@zamanraja9531 so prospective fault current (ipf) is the highest of PEFC and PSCC. This is recorded in the nature of supply parameters. Zs ie (R1+R2) + Ze is recorded on the schedule of test results.
Can someone advise me about how the instrument gets the current at time 4:33 please ? Are some assumptions made in the calculations ? How can the source impedence be calculated without removing the mains supply voltage ? I read elsewhere that in some instances a standard impedence value is used for the suppliers network and thus the max current is calculated. Is this true ?
Hi. The kA rating is either on the side or front of circuit breakers. The measurement is only done once above a (any) breaker as shown in the video as this will be the same reading (PFC) for all of them. Hope this help and all the best GSH Electrical
Sorry, what I meant was that in the box on the test sheet asking for the value of KA, do we wright in the value written on the side of the breaker, or the value we have measured? Cheers Andy
I carry out this test with a similar tester . But I never changed the leads over( l-n& l-pe)would this have any effect on the test results ? Also , should the fault current reading between the tails be greater than the rating (eg 100amp)
Hi. No worries on the test leads. The fault current (PFC) at the tails can be up to 30kA the PFC rating of the 100amp cutout fuse is either on it or look in BS7671. It’s the fault current it can clear not the load current which as a rule of thumb is 1.5 Times it’s rated value so 100 amp fuse could carry up to 150 amps for a short period of time. Hope this helps GSH Electrical
Hi Gary Can I ask a question. Why have not locked off the main switch before taking the cover off and why do you need to do PFC test for each circuit rather than just at the input to the main switch. GN3 and both Napit/niece guides always show locked off powered down CUs whilst doing this test. If I had done this during assessment I would have been failed.
You will never get an answer from him because in this industry no one knows what to do . I had once two different assessment within couple of months and both assessors were saying something else.
Learners have the conductors in and out of this board every day... I didn’t have time at 7am when shooting the video to sort them out. All the best Gaz
@@GSHElectrical Sorry yes, I didn't think it was you guys and I suppose RU-vid possibly can't tell certain advertisers they CAN'T have certain spots but it just seemed a little like letting a rival try to cash in on your hard work and success. Just seemed a bit of a "dick move" by RU-vid and indeed TS4U....
