1. W

    what is the formula for calculating PSCC for final circuits?

    hi in college and watched some YouTube videos and read up on things I think I got the right formula but I'm not sure. Zsc= Zesc(or Zdbsc) + (R1+RN) (R1+RN) = milli ohms/metre x length x correction factor and then divide that by 1000 Zesc = Uo divided by PFC Then add together Zesc and (R1+RN)...
  2. E

    Generator Protection and PSCC values

    I was asked to go and take a look at a generator set up by a marquee company yesterday to do some testing. It was a brand new JCB 65QS with 209hrs on it (58.7kva prime). The generator was fitted with a socket pack from the bus bar with 3 x 16a on 30ma RCBO, 1 x 32/3 on a C curve MCB and a 63/3...
  3. K

    Question about Zs and PSCC needs some clarification thanks

    Hi everyone Recently I have come across an advert of someone selling Afdds C type and the person mentioned the need to sell because Zs was too high so he was considering changing the circuit breaker back to B type as it allows enough Zs to meet the regulations. As Afdds is also combination of...
  4. B

    Pscc and Pefc

    Can anybody give me the definitive answer to the question of why on TNCS earring arrangement when testing Pefc and Pssc sometimes the values are different? When we are essentially testing down the same path as the earth conductor and neutral are combined? And therefore both share the same...
  5. B

    Ze=1.87 TT or TN-S?

    Morning all, Looking for some opinions MK Sentry Dual RCD 63/30 CU Fluke 1662 readings... 2 lead hi current Ze= 1.87 Ohms PEFC = 6A PSCC = 0.774kA 3 Lead no trip Ze = 12.95 Ohms Zs at cooker/sockets = 12.56 RCD times are compliant No electrode visible and Gas & H2O 10 mm at board...
  6. M

    PSCC from canal boat inverter

    I am soon to be helping a friend with his electrics on his canal boat, he is looking at putting a small consumer unit, with a circuit for sockets and another for lights and upgrades to sockets wiring etc etc All sounds easy enough but I am wondering how to select the correct short circuit...
  7. J

    Ze & Pfc (Pefc & Pscc)

    I hope someone can help me as im getting different answers off different people 3P & N Supply Ze: Disconnect main earth Set tester to 2 lead high L+PE (is this correct?) test between L1 - E / L2 - E / L3 - E recording the highest reading Ze (reconnect main earth) Pfc (Pefc) Set tester...
  8. B

    PSCC on 460V Split Phase Supply

    Hi all. Been doing a bit of work on a pub out in the sticks with a 460V split phase Supply. When tried to test phase - phase PSCC my tester didn't play along. I was going to use the double p - n rule of thumb but then I got thinking, does this still apply to a 460v supply?
  9. J

    Ze, pefc and PSCC on am2

    Hi, Could someone who has completed their AM2 please give some advice? When commencing your ze, pefc, PSCC. Do you set your megger tester to high or low. I would normally set it to high for the ze, pefc and PSCC tests? Although, I have been it should be set in low because of the RCBO on the...
  10. R

    How to carry out PEFC and PSCC on a three phase db with a rcd as the supply?

    Ive got my am2 resit tommorow for my live testing and I ran out of time and failed as well as I carried out the ze test on 2 lead high thus tripping the rcd. So now I know for next time to complete this on a 3 lead LOW test and measure ze with earth disconnected etc.. then connect main earth...
  11. R

    Just had Refresher Course for AM2 Exam is Monday need help with PSCC and PEFC!

    I have just been on the refreshers course for the Am2 exam that I am about to sit on Monday coming. When the tutor was going over PSCC and PEFC. I was confused, completley thrown. So in my head I would do:- I would carry out this test on the Incoming Tail side of the 3 phase board? PSCC:-...
  12. M

    Recording PFC and PSCC results

    I have my Am2 this week and am getting confused with what reading is to be placed in schedule of test results. I understand for PFC to take the highest reading between 3 phase and earth but have to then go between phases & N to find PSCC. Is it PSCC reading then doubled and put on back of test...
  13. NDG Elecs

    Wandering PSCC value. Is my meter goosed....

    Hi folks, Just a quickie.. Testing PFC earlier today, specifically PSCC... Got a reading of 3.4kA, then did a double check straight away and got 2.1....ooh I thought so tried again and again with values ranging between the two figures above. Never had such a deviation in quick succession with...
  14. uksparks

    Pfc / pscc

    Hi, If you have a TNS supply, you would have a separate earth path by way of lead pipe or split concentric etc... true? Ok, so if you have a PME / TMC-S supply, the earth connects to the neutral at the service head, yes... true? Ok, so just out of interest, if you had an overhead TT thats now...
  15. V

    Pfc and pscc

    Could anyone out there give me a detail explanation on what is the above test reading proving, is it that you have for a very low reading good continuity through the connections at the equipment at the origin of a installation. And what makes the reading vary from one installation to another.
  16. driverman

    Pfc - pscc on 3 phase supplies

    Hi, Guys,when measuring PFC-PSCC on 3 phase supplies,I know that you test between live conductors L1-L2, L1-L3, L2-L3 and then all 3 to Neutral and note lowest reading obtained. Then all 3 phases ( is that right term for C&G? ) to earth. Then neutral to earth and lowest reading obtained recorded...
  17. S

    PSCC and PEFC using Kewtech KT60

    Hello Lads and ladette's Upon performing PSCC and PEFC on a newly calibrated (as in March 2014) KT60, I m getting a 'OL' reading. This has now happened on several occasions in both flats and houses in different towns. Can anybody help me out..? Cheers,
  18. K

    Relationship between Cut-Out Fuse & MCB PSCC

    Good morning all, Apologies if you have gone over this a number of times before (I have tried searching for a thread, and have found some that have touched on what I'm after but not quite explicitly enough). If the measured PFC is greater than 6ka (for example) with circuit-breakers' breaking...
  19. F


    Hi can you refresh my memory! I am downstream from an RCD, trying to obtain PSCC do not wish to use meter as will trip RCD, can someone remind me of the calculation to obtain PSCC, to complete PFC. 230v, 45.9 ohms on TT stake. Many thanks
  20. N

    Max PSCC 1 phase and 3 Phase

    Hi all. Prospective Short Circut Curret. Now , if you measure the impedance on a installation P to N , and get a reading of 0.21 OHMS , the max current flow between these two points P and N will be 230/0.21 = 1095A.....1KA. Now if you have 3 phases , and each are the same impedance P to N ...


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