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  1. Michael J

    The maximum value for Zs on a TT system is 50/I delta. So for a 30mA RCd is 1667 ohms

    why is this not the case if the final circuits on a TN-S or TN-C-S system are protected by a RCD? Funny what you think of when you can’t sleep
  2. U

    Why I get netagive value from power meter (powerlogic pm500) for the reactive and Active Power?

    i read data every minute, and some time i get negative values, can any one explain me, i'm not an electrical engineer (i'm IT developer) so please be nice with technical terms.
  3. 1Justin

    Best value fused switch plus 2 module type 2 SPD?

    Has anyone done this yet on a budget? I'm pricing a job to run a submain off a TN-S. I'll need a fused switch incorporating SPD alongside in the same enclosure. Price sensitive. Thinking of a budget Lewden off the shelf fused switch (in 4 module enclosure), ditching the enclosure and buying 6...
  4. Vortigern

    Calculation of capacitor value for conversion from star to delta

    Hi does anyone have a notion of how to calculate the capacitance value for the above?
  5. R

    Phone calls asking if I want to sell/know value of my Business

    Hi all, I`ve been trading for the last 8 years, in the last 8ish months I`ve been getting calls from firms asking if I would be interested in selling my business. Also getting calls saying that they have clients that want to invest in the area and would I sell or when I say no they ask whether I...
  6. HumbleWorker 91RT

    Best Sockets for value and longevity?

    Just wondering which sockets you guys tend to go for, your typical plastic units for internal no brushed steel effect types, as well as your external 1 and 2 gang 13 amp. Based on price low to hi, brand perceived view (high quality through to Chinese crap) and ease of installation has good...
  7. E

    When Filling Out A N.I.C Installation Certificate Online *DEFAULT PFC VALUE*

    Why does it try to give you the value of 16KA in the drop down box for prospective fault current. Has anybody else come across this or do they know the reason why? I always put my measured value in but still would like to know the reason they try to give you the above value.
  8. polo1

    Exceeding max adjusted Zs on a board change.

    Testing during a board change, a RFC on a 32A 60898, with rcd protection, you find that the max Zs is exceeded by 0.1 ohms using the no trip setting on your mf tester On the EIC do you - A) simply record the actual measured value B) record the actual measured value and note the position under...
  9. 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...
  10. L

    Soil resistivity

    Hi, How can I change earth resistance (R) value into soil resistivity (Rho)? Is this formula correct, ⍴ (Rho) = 2πAR (A = Distance between pegs, R = Earth resistance). Regards, L.
  11. haptism

    SWA test results

    Hi hope someone can advise; ive not done alot of testing or filling out eic's and am a bit stumped on this. I have run the usual dead tests on a 3 core swa cable used on a final circuit all tests are good. However the amour (which needs to carry the full fault current), does it not need to be...
  12. A

    Comparing heating usage Propane vs Elec

    Hi there, I do hope this is the right place to post this! I basically want to compare energy consumption in heating between two buildings. Building A has a purely electrical heating system and I can get how many kWh are consumed in one month. Building B has a gas boiler which uses 47kg...
  13. J

    Questions in power engineering interview

    I would like to seek advice from experienced guys because I have interview test for my power engineering as below. Thank you. a) For 600A switchboard, what type of device setting need to do? Can I say that I need to do setting for direct acting for MCCB since more than 100A and earth fault...
  14. A

    Ze/Zs of 3 phase supply

    Hey all, going over some testing before my final assesment. i've heard a couple of times when testing a 3 phase supply using a single phase to earth test you double the reading as your Ze/Zs, so if you test L1-E=0.07 Zs=0.14. also what i have done until now is test all three Lines to earth and...
  15. G

    mixer value on underfloor heating?

    HI all, installed a s plan, well i say s plan, heating up stairs and underfloor down, there is a 3 way manifold for the underfloor heating, a couple of question regarding that pls 1 actuator came , but there is a value i open with that stat so i assume i dont need the actuator ?? also i...
  16. S

    Checking loop tester readings from a sample socket.

    After calibration of my loop tester,I am considering using a socket in the house for future calibration checks and to connect various low resistances in series with earth via a rotary switch to give a range of readings,and if so what value of resistors?Thanks for any advice...
  17. G


    Q, The earth fault loop impendence measured for a circuit is L1.1 0.61 determine showing all calculations weather it complies with Bs7671 what do I need to do
  18. A

    Max permissible ZS for rcbo 61009

    So, when I did my 2391 I&t course I was told to use to values in table 41.3 of the regs for max ZS value for rcbo which provide earth fault, and over load protection. Recently a colleague of mine said you should use the value in table 41.5 which states a max permissible ZS of 1667 ohms. I don't...
  19. E

    Twin and earth testing

    Hi, A quick question, maybe a stupid one .... but it baffles me ,and I cannot find any info on the net. If you do the continuity test on a lighting circuit to get your resistance values, wired in twin and earth, how do you the the value for the earth ? Obviously you link the earth and phase or...
  20. Farmelectrics

    rcd tripping times

    just a quick one doing some rcd tests today, and at x1 value the tripping time was 46mseconds and at x5 29mseconds now i no that as long as at x5 value is under 40mseconds all is ok just thought the x1 value was a bit high so my question is there a max value for times 1 as i must admit not had...
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