loop impedance | Page 3

loop impedance

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  1. S

    Ze external earth loop impedance

    Hi I've done a Ze test on a TNS system and it's come back as 0.14 ohms is this reading ok as the max is 0.8 is there not a min amount you can have thanks
  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. 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?
  4. 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?
  5. 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...
  6. sparkdog

    Megger earth & loop impedance testing event.

    Got a letter about this free event.Anyone think its worth going to?
  7. 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...
  8. 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
  9. 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...
  10. 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:
  11. 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...
  12. F

    Fluke 1563 - Loop Impedance Test problem

    Does anyone have a problem with their Fluke 156X testers when doing Loop Impedance Testing ? Most of the earth systems I come across are TT and my meter will on the odd occasion show >2000 ohms and then on a repeated try I get the correct answer. I think the problem gets worst when the L-N...
  13. A

    Cable selection, calculating earth fault loop impedance

    Hi guys, struggling to work this question out and don't seem to be getting a correct answer no matter what cable conductor size i use. Q. A 230V 14kW domestic electrical cooker, installed in a house is to be supplied by a 15m run of PVC insulated and sheathed cable, clipped to a surface. The...
  14. G

    socket testers earth loop impedance indicators

    can anybody tell me if these are worth using as a fault finding tool they claim lots on them,anybody used them?:icon3:
  15. R

    why a low earth fault loop impedance

    hi guys, Just wanted some help with some course work for college. Any help is greatly apprecitaed. Why should a low value earth fault impedance should be achieved for all circuts? thanks
  16. M

    Earth Loop Impedance Test and problem with power supply

    Hi, Our main fuse from the power distributor blew and Western Power attended and replaced. During this visit they established that their was a problem with reverse polarity and that when the RCD was installed the tails in the grey twin cable were connected red-black in the top of the consumer...
  17. B

    Calculate Earth Loop Impedance - Cable >35mm2 Impedance Data

    Hi all, Where do I get phase (Z1) and earth (Z2) conductor impedances to calculate earth fault loop impedance? I have seen (R1 + R2) tables which give combinations for cable sizes up to 35 mm2. What about cables > 35 mm2? Can I use voltage drop tables (for phase conductors) from Appendix 4 in...
  18. S

    RCD Upstream BG board HIGH LOOP impedance

    A domestic customer has MK dual RCD board #1 and another BG dual RCD board #2 in loft. On testing, a couple of circuits (32a & 16a radials) on board #2 had high Earth fault loop impedance ( over 3 ohms for a socket radial). I know that the BG board (in the loft conversion) does not really need...
  19. T

    Earth fault loop impedance readings through a UPS supply

    Does anyone have any experience in recording values of EFLI on circuits fed through a DB supplied via a UPS please? The meter shows the above scale arrow. I understand that there will be no reference to the external earth due to the inverter inside the UPS but what will happen to the UPS...
  20. H

    sMaximum earth loop impedance for TN systems, and TT system

    I am finding this quite a complicated subject, and I would really welcome your thoughts on this subject. If I could start with a TT system, according to regs, 411.5.3 states that when using an RCD for fault protection purposes, then the following has to be applied. RaxIn<=50 This means that...

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