impedance | Page 4

impedance

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  1. F

    Fault current

    Can someone explain why fault current is higher when your zs is lower trying to write down reason but struggling on what to put
  2. V

    240 but no earth loop impedance

    I'm testing a job at the minute and today I went to a double socket that has 240 at it but when I carried out a ELI test the result is a open circuit .the 240 I am getting is between L-E and the means of earthing is TT ,it's a radial circuit supplied bu a 20amp breaker totally confused??????
  3. H

    Suitable testing instruments

    Hey guys, I need help finding out which tester you'd need to test for: continuity of circuit protective conductors, earth fault loop impedance and prospective fault current. I'm pretty sure you'd use a low reading ohmmeter for continuity but I don't know the other two. Also, any requirements...
  4. M

    Earth Faulth Loop Impedance HELP!!!

    Hi can somebody shed some light upon correction factors for earth fault loop impedance. I know that the vales of zs in bs 7671 are if the conductors are running at max temp ie worst case scenario , am I right in believing that if you get a measured result you apply 0.8 to it?
  5. G

    External earth fault loop impedance Ze

    ​Can any one explains what are the three methods to find External earth fault loop impedance Ze please?
  6. S

    max measured earth loop impedance query

    Hi guys, Im just filling in my first ever solo EIC when I check the onsite guide and gn3 for max permitted zs (tabulated) for bs60898 type b 32A the table shows 1.16ohms but to me it didnt ring a bell, checking bs7671 table 41.3 shows max zs to be 1.44. Can anyone shed some light on why and...
  7. sparkdog

    Megger earth & loop impedance testing event.

    Got a letter about this free event.Anyone think its worth going to?
  8. P

    1st Generator install

    I have been installing a 3 phase 60KvA generator connected to a MDU with a 100A 0.1A RCD, when I test the earth electrode resistance (Ra) using the earth fault loop impedance tester I get a reading of 1845 ohms, as this does not meet the Ra x Ia less than or equal to 50v, 1845 * 0.1 = 184.5 , it...
  9. K

    Earth Fault Loop Impedence question

    hello, i got this qustion and would like someone to show me the working out of it please. the measured value of loop impedance for a circuit is 0.83 ohms. if the temperature at the time of the test was 20c and the cable is 70c (factor1.2), what is the correct value. ze = 0.4 ohms
  10. W

    Caravan Earthing, Higher impedance?

    So I have a static caravan that has a hookup to the house, And I wanted to improve the earthing by installing one specifically just for the caravan, So I have driven in around 4ft of copper pipe and used 30a capble to earth both the chassis of the caravan and the metal exterior, but upon...
  11. R

    Earth Loop Impedance on a TT system

    Afternoon all, I did a standard Ze test on a TT installation yesterday, and got a value of 215 ohms. The ground is really wet at the moment and so I'm assuming its about as good as the rod is going to get. Would simply replacing the rod with a longer type improve the Ze result? and if not...
  12. sparkymalarky

    MCB's 230V/110V Zs Earth fault loop impedance values

    I give these out to some of our younger electricians in the aim to get them familiar with such values. Probably old news to most of you fellas but sure it won't do any harm. Calculations from BS7671 anyway, just handy to have a hard copy other than BGB. Cheers John
  13. S

    KEWTECH KT64 loop testing..

    hi guys when measuring loop empedans with kt 64 it gives me 2 option by chosing with f1 L-n l-pe which one shoul be used?? Thank you very much..
  14. S

    AC Circuit Theory Maximum Power Transfer

    Hello All, I am currently hitting a barrier with regards to the basics of this question. It is for a HND so I may have put this in entirely the wrong forum. Apologies if so. A 50HZ supply is connected to various given impedance's connected in series and parallel. Calculate the value of the...
  15. T

    PME Earth Impedance and RCT times - advice ;-)

    Hi all, great site and sorry for the long post - I'm after some advice as I don't have total confidence in the 4 sparkies I've currently used with regards to the test results on my cert. That said I am not a sparky and if I'm being a total muppet please tell me - I can take it :-)...
  16. M

    Prospective fault current ?

    Can somebody please clear up for me what is prospective fault current? Am i right in thinking its the value of overcurrent you get through fault conditions like short circuits and live conductors and exposed conductive parts ? Thanks
  17. P

    0.05 Max Impedance for Main Bonding Conductor

    Got massively ribbed on another post for not knowing that max impedance for a main bonding conductor is 0.05 ohms, so I expect some more for this post!....... I'm going to assume there is a very simple answer for this, but despite me going blind reading GN8 I can't for the life of me work out...
  18. E

    Earth Loop Impedance testing

    I have a standard KT71 pat tester and have been offered a job testing cash registers. The problem is I will be expected to also carry out an Earth Loop Impedance test and I do not possess the kit or the knowledge to do it. I am considering sub-contracting the Earth Loop Impedance testing part...
  19. rustynails

    2392 Question: Maximum earth loop impedance for 20A BS88 (gG) fuse

    What is the maximum earth loop impedance to BS7671:2008 for a circuit protected by a 20A BS88 (gG) fuse giving a 5 second disconnection time is: A: 7.42 B: 2.91 C: 1.84 D: 1.35 The green book says the ln for this type of fuse is 78A p299, that doesnt give you the right answer though. :confused5:
  20. P

    earth loop impedance

    client had washing machine eng. called out....who tested the single switced socket??? (w/machine drum fault) and on his rport indicated a higher than acceptable earth loop impedance (254 ohms) as a result im sent to check installation...theres nothing wrong with the installation however a...

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