values | Page 2

values

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  1. A

    Zs values when there is additional RCD protection

    Hi everyone, Consider we have an RCD+MCB protection for a circuit. if we follow the tables for Zs values of a 10A, MCB, type C, the maximum value shall be 1.75 Ohm, this happens when 100A current flows ( as per MCB breaking curve). When the RCD disconnects the circuit in much less current, why...
  2. R

    what do the current values mean in this meter?

    In the picture can be read 10(40)A. What is the capacity of the meter 10 A or 40 A, why are there two values?
  3. P

    45A breaker max Zs values

    Hi all, Why is there no max Zs value for a 45A type B breaker in table 41.3 of 18th edition? What value should be used as max value on schedule of test results? Cheers.
  4. gazdkw82

    Maximum Zs values for BS3871

    Where can I find the max Z's value for a BS3871, type 3, 32A MCB? Iv had a look through BS7671 and done some searching online but I cannot find it. IV found some tables with listed Zs values for a 3871 but I have no idea where they originate from or how old
  5. V

    tabulated values of Ze and Zs

    right I get a bit confused with working out the Tabulated values (I am training and have exams tomorrow for Initial verification) on the Ze and Zs anyone on here what to explain how this works on the earth loop impedance, please can someone explain what I am overlooking ?thanks, Jules I...
  6. 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...
  7. Gary Tollison

    Earth fault loop impedance - textbook values vs BS7671

    Hello. I'm in the final stages of completing my electrician course, and I find myself confused (again) by EFLI. In the textbook provided is this: Uo 230V see below for each circuit. Calculate the maximum Zs for each circuit: Complete the table. The answers given in the textbook are said to...
  8. Zdb

    Max Zs values. (20 characters)

    So I've been told by the NICEIC not to use the 80% rule for max Zs (even though that's the table provided on the inside of the cert books). They want me to use the 100% values from table 41.3 in the BYB. Not a problem. However I can't seem to find a table for the BS EN 3871 MCB's in there...
  9. soms

    Maximum permitted Zs values for circuits with TT earthing system

    Hello, I am assisting my supervisor and getting some first hand experience of completing certification by filling in an electronic copy of an EIC, working from a handwritten circuit schedule with test results and my memories of the installation work. I am at home so cannot ask him for advice...
  10. J

    Resitance values on a 2kw electric heater

    Hi all, Repairing a 2kw convection heater in our workshop office and I'm getting zero resitance on the min/max dial at any setting. What is the value for min and max as need to lever the spacing to get a resistance but don't know if it's too much or too little Cheers
  11. CDB

    Lighting Circuit r1+r2 values.

    Hi, I was doing my r1+r2 tests on a lighting circuit yesterday in a 6 bed house over 3 floors. Approximately 20 points not including switches. Mainly pendants but some light bars etc and almost all LED or low energy halogen type bulbs. Closed circuit r1+r2 values range from 0.88 on ground...
  12. G

    Understanding Zs values

    Can anyone help me understand Zs values. In the On-Site-Guide page 60 Table 7.1 under the heading Maximum cable length, it states if Zs < 0.35 ohms for a TN-C-S system you can have a cable length of 107m In BS7671 page 58 Table 41.3 it states the Maximum Zs for a 32A CB to operate within...
  13. L

    R1+R2 Values

    Hi all, Quick question when doing r1+r2 testing wether its a new install or a EICR, is there a table to show maximum readings we should be getting? Or is it a calculation? Thanks in advance Luke
  14. P

    80% values when and why?

    I know that the 80% values are applied in regards to operating temperature etc but NIC paperwork asks for the max permissible values of bs7671. So when do you guys apply the tabulated values? I've done commercial condition reporting in the past with a company that used their own test sheets...
  15. haptism

    R1 + R2 of ring circuit

    Hi for a ring circuit, is there any need to measure and enter R1 + R2 values on a schedule of results ? Because an r2 value is already measured (together with r1 and rn). If I needed a ring R1 + R2 value to calculate ZS (although i would find ZS with a socket tester so really no need; but if I...
  16. D

    minor works high Zs Values

    test, cant seem to post????
  17. L

    Zs of circuit higher than maximum values allowed?

    Hi there, I have a ring circuit where the Zs reading taken is higher than maximum allowed values. the circuit is protected by a 32a RCBO type C device, Zs = 1.43. I have currently have tightened terminations which has brought it to its current value. as i have been out of the game for a while...
  18. gazdkw82

    Earth fault loop impedance

    Iv been given the scenario: 6 circuit earth fault loop impedance values were recorded. Each circuit has type B cb. referring to the maximum values, show by calculation if these values are acceptable. so I can't do zs =ze+R1/R2 because they've not provided me with ze. doing some research it...
  19. gazdkw82

    Tubulated values

    Hi, im studying at the moment (currently on testing and inspecting) and have come across the term tabulated values. Can anyone explain the meaning?
  20. G

    High ZS values on rewire

    Hi all, Only recently joined the forum, and thought i would get some views on the following. Just wondered if anybody has had the following issues when fitting a new ccu. Recently completed a rewire, including new new metal ccu, completed all dead tests ok, however upon live tests i got high...

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