high zs

  1. J

    UK High Max Zs

    Undertaking an EICR and there was a high measured Zs on the B30 MCB Ring Main circuit (TN-C-S) - No RCD protection on any circuit. Lighting circuit for building extension is spurred off ring main, max R1+R2 recorded was 1.84 (Zs 80% = ~1.17). As I understand it, though not ideal, the remedial...
  2. S

    High Zs on auxiliary circuits

    Hi I have a distribution board controlling conveyor belt in which all auxiliary circuits for start/stop switches, emergency buttons, etc are supplied through 230V/230V separating transformer.where secondary winding is earthed on one end. I've got high Zs readings for all those control circuits...
  3. S

    High Zs on a Campsite

    I have been asked to provide a quote for a supply to an toilet block on a campsite. The three phase supply to the campsite is approx. 150m from the mains incoming supply and fed off an 40amp type b mcb. The cable is 35mm 5-core SWA. The issue I have is when I measured the Zs at the campsite DB...
  4. L

    Very high Zs on ring main.

    What would be the fault with a very high Zs at all sockets on a ring main, the sockets are an average of 68.10 . The lights are.67 and the is a socket radial circuit which is at .51 .
  5. Simthespark

    3 lead low Err5 code Fluke 1664FC

    Hi All New to this forum, have read the posts on here from google but only recently signed up. I'm having some issues and some input would be very handy. Testing at my house. I have a TN-S supply. Cutout is circa 1980s, cable is circa 1940s. Lead PILC incomer encased in a 1-¼" (32mm ish) old...
  6. banny07

    UK I am getting very high zs readings

    Hi Guys. When measuring zs I get very high reading. Ze is 0.3 (tns), zdb is 0.21. r1 and rn are is 0.42. r2 is 0.72 , r1+ r2 is 0.29 . when I test zs it 8.26 ohm new to testing. I even buypassed rcbo but it stays same. Do you think my mft if faulty? Any thoughts guys? I am new to testing.
  7. telectrix

    High Zs

    Interesting one yesterday...... my remit was just to install a outdoor socket direct throuh wall (back to back) from existing double socket inside. existing socket on a 32A RFC , RCD protected on recently fitted dual RCD board. testing time and Zs is 1.59 ohms, obviously > tabulated value even...
  8. J

    High Zs reading

    Hello, looking for some advice on 2 things please. Ive tested a ring main in a house with RCD protection, the results ive had are L-L .43 N-N . 41 E-E 1.17 I had a look for a loose connection but can’t find anything, how high does the CPC reading need to be before you would consider it ‘to...
  9. W

    Why is a too high zs reading on a circuit okay if it’s protected by an Rcd?

    Not long passed my test but was wondering why it’s okay for a circuit to be over the max zs if it’s protected by an RCD?
  10. F

    high zs reading advice please

    an eicr was carried out to an industrial plant area were the zs readings were all high readings above the maximum for a tns installation i noticed that the supply cable in question was getting monitored by an elcb. However recently the company or contractors. have driven in earth rods local to...
  11. B

    High Zs RCD for fault protection?

    Hi, kind of follow on from my last post, but my boss hasn’t explained very well hoping you guys can High Zs on circuit, Can you reply on an RCD for fault protection? He’s told me if the circuit is RCD then you can use that as fault protection, obviously you can’t meet disconnection times for...
  12. B

    High Zs

    13amp FCU off ring main supplying sockets in shed. Zs at furthest socket in shed is 1.26ohms which is too high for a 32 amp mcb. Would you use the 13amp fuse in the FCU to meet your Zs reading? Zs at FCU is 0.70.
  13. peeko

    Zs @ DB very high

    Hi all, Went out to fit some LED lights last Friday for a customer who's taken on a small workshop to be mostly used as storage. All fairly straightforward until I came to test for the minor works cert - got a Zs reading at the Db of 2.24 ohms - had a quick look and it's only got a 6mm supply...
  14. cliffed

    Short circuit compliance on high Zs readings

    Would you divide the 5.13 ohms by 4. I personally don’t think so. Also the R1 /Rn short circuit resistances are different from the usual R1 /R2 measurements. Found those in an electrical book by,that man. The Zs on this circuit was above the permitted figure,so just had a play around to see if...
  15. P

    High Zs on SWA Armour / New Earthing Conductor

    Hi all I am after some help/Advice if possible please A SWA sub main Distribution circuit has been given a Code 2 Rating on a recent EICR due to a high Zs of 2.8 ohms. The cable is 180 metres long and runs underground in ducting. The Install is from a few years ago when a new Substation was put...
  16. R

    High Zs on submains and high Ze

    Hi chaps. On some remedial works at a school, I have a sub main a 16mm armoured feeding it about 50m away from the main DB. Fed from a C63 triple pole 60898. The issue I have is the Zs at this submain is 0.46 which is way over the maximum permitted. But the Ze at the main DB is 0.35. On a tncs...
  17. D

    High Zs values (Just)

    Given that Amd3 reduced max Zs values slightly what is everyone coding if a measured reading falls between the pre Amd3 value and the post Amd3 value. Failure to meet disconnection times would normally be a code 2, but a code 3 seems appropriate here......maybe a note to explain? On E-certs it...
    • Deleted member 9648
    • Thread
    • high zs values
    • Replies: 73
    • Forum: UK Electrical Forum
  18. F

    high zs readings on site cabin

    carried out dead testing on new site accommodation,all dead tests were fine however, when I conducted live testing I got high zs redings on lighting circuit 22 ohms, fused spur for heater 21 ohms so I thought maybe its a tt system but when I tested sockets I got a reading of 0.69 ohms ze at...
  19. Dannyg8810

    High zs on low bay lighting circuits

    just been looking through an EICR we've had done and there's x4 circuits on D type mcbs which have been given c2's as the zs is higher than the maximum permitted...... Iv looked c type would bring this within the maximum permitted I don't see why these need to be on D's 2.5 t and e on 20a...
  20. T

    High Zs value with 2 sockets

    Hi all, Doing some pre board change testing and ive found 2 sockets with high Zs readings. Everything else is fine, done all my end to ends and the Zs's are what should be expected. A couple of the sockets have Zs lower than expected but 2 are higher. They should be about 0.8 ohms but ive got...
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