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impedance

  1. M

    Industrial Excessive earth fault loop impedance

    I work for a hotel chain and recently we’ve had our 5 yearly test they have 8 circuits from our LV panel with excessive loop impedance readings !! So apart from either introducing an rcd or dropping mcb ratings or type is there any other way of achieving satisfactory readings ?? Also if I have a...
  2. LewisM

    6A MCB Tripping on Earth Fault Loop Impedance Test

    Hi, just finished a partial rewire at my sisters house and when testing the two lighting circuits (up&down) the 6AMCB trips for both circuits individually, I thought the MCBs might just be sensitive to the test but the smoke alarm circuit also 6A is fine when testing, R1+R2 and IR test all fine...
  3. Gary Tollison

    Earth fault loop impedance, initial verification, multiple DB

    Hello. Not sure if this is the correct forum to post this in (still trying to work out where the trainee section is). Just been doing some practice fault-finding online. Found this scenario: After doing initial verification on an outbuilding with its own DB, which is supplied from the main DB...
  4. N

    earth fault loop impedance calculation

    hello all could anyone help me i am doing my 2392 and i am a little stuck i have been asked a question which is using the following measured value of loop impedance 0.5 (40amp bs en 60898 type b mcb) ferfering to the maxium tabulated value given 1.15 show by calculation if the measured value is...
  5. T

    Potential earth loop impedance issues for second floor flat

    Hello! After years of renting I'm currently in the process of purchasing our first property. We've had an offer accepted on a 1 bedroom flat in Surrey. However there are questions over the electrics, and knowing little about electrical wiring I'm a bit stumped on how bad the electrics are and...
  6. 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...
  7. C

    Refurb works In offices

    Just your thoughts on this one,doing a part refurb on existing offices,no initial verification or certs found anywhere. Premises rewired bout 1990,adding sockets here & there in each room. The DB is a Crabtree Tpn polestar,just finished some loop readings ,& not good,1.49 the highest,there is...
  8. M

    Loop Impedance Testing - Strange fault code

    Being doing a domestic bathroom refurb', lighting, altering shower circuit (have a Megger 1730 MFT). History, property has no RCD protection, but as it was a Hager CU, had contemplating using RCBO's (TN-C-S supply). Before doing any work, I decided to clamp the meter tails, as the property has...
  9. soms

    Earth loop impedance measurement affected by dimmer switch

    Working on a job today which included a very simple new lighting circuit. The lighting circuit a very short run from a distribution board to a single switch position, which then supplies a single luminaire. The customer wanted a dimmer switch to control the fitting. To crack on and perform the...
  10. Gary Tollison

    loop impedance, temperature, cable factor....

    Hello I'm not sure if this is the correct forum area to post this in, apologies if it isn't... I've been working through some mock questions on-line, and found myself confused by this: The measured value of loop impedance for a circuit is 0.83ohm. If the temperature at the time of the test was...
  11. Gary Tollison

    earth fault loop impedance

    Hello :) I'm confused about EFLI which I am guessing should be relatively straight-forward. I can't get my tired brain to figure out how to calculate the value for EFLI on system-side circuits? eg: what should the actual calculated value be for a 40A circuit, and how do I get that figure...
  12. LeeH

    Resistance of a transformer windings.

    Does any of you clever chaps know what the resistance of a 5kVA transformer should be? It's a 240-110 CTE. I have a resistance of 0.16 Ohms (1400A) If I recall what little transformer theory I covered years ago the impedance will increase when energised but how much I have no idea...
  13. B

    Zs,Ze,R1+R2

    Zs=Ze+R1+R2 if you have R1+R2 and the Ze of cu through dead testing what is the need of doing an earth fault loop impedance test once you've energised the cu?
  14. C

    Fault Current Distribution

    Hello All, 1.Star connected earthed neutral Source to Star connected earthed neutral load? Say if a L-G fault occurs between the source and load, How does the fault current gets distributed? To the source side neutral or load side neutral? 2.Star- Star Transformer. Neutral earthed on both the...
  15. S

    Spanish Earth Road installation

    Hi, Quick question, does anyone know if there is a different spec to the U.K. for earth rods? I'm told in Spain they are longer but not sure if that is correct? Also are there any regs in Spain relating to the positioning of the rods etc (i.e. distance fro property)? Any advice greatly...
  16. G

    Earth fault loop impedance

    How does earth fault loop impedance and disconnect time requirements change for 3phase 3 wire 230 volt systems where the phase to earth voltage is 133 volts instead of 230 volts?
  17. S

    Battery Storage And Uk Regulatory Compliance

    Hello all, I am thinking of adding battery storage to my existing setup to increase self-consumption and provide backup for power cuts. Currently I have 16 x 230W panels feeding 2 + 2 kW StecaGrid inverters installed in 2011. If I were to add for example a Victron MultiPlus 48/3000/35-50 in...
  18. S

    high pfc domestic property

    hi, fitted new consumer in a domestic house. testing. ze 0.16 zs at origin 0.04 pfc 6.2ka the pfc is my problem, ohms law would make the pfc work out around 5.7Ka (using 0.04 as your resistance) (with all paths in place) using megger 1553 two lead test, high current, pefc and pscc are the...
  19. Rob

    For Sale [North]: Megger LTW 425

    http://www.test-mete...dcXmBoChmzw_wcB Same as the above, it's a year old but has only been used 3-4 times tops. I don't think it's in calibration still, but I can arrange to have it calibrated for anyone interested. Key specs below: Will post some photos when I get home later. I think...
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