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  1. C

    How do i calculate the total resistance in a series-parallel circuit?

    Hey, I'm an electrical engineer in training and i was wondering how you could calculate the total resistance in a series-parallel circuit? I attached a picture of what it looks like. If it's to any help resistor 1 is 2, r2 is 3, r3 is 4, r4 is 5 and r5 is 6 Ohm. Thanks for any help
  2. B

    How do I calculate the resistance of a spur without phisically testing ? ..

    Boffins of the electrical world ... How can I calculate the resistance of 48m ring 2.5/1.5 .. with a 8m spur .. I can quiet easily do this without a spur in the equation but , my test papers require my doing so with an 8m spur. . how does this affect the zs tests ... Thanks v much ...
  3. C

    Rise in resistance during test video

    Why does the resistance go up during this test? View: In fact it goes up several times during the video. Is this the wire charging up from capacitance? I'm clueless.
  4. KeenPensioner

    Insulation resistance with broken line conductor

    Hi, I'm not an electrician but I'm studying the material required for the C&G 2394/5 just for the sake of it. I think I understand the theory behind insulation resistance testing (but maybe not!) and the reason the test is performed at 500V (insulation condition, fault finding) and that loads...
  5. S

    Insulation resistance testing

    456megaohms on a 25m 3core swa is acceptable as its more than 1megaohms. Correct.
  6. happyhippydad

    Global Insulation resistance <1MΩ but individual circuits are all > 1MΩ

    With regards the title is the reason for this because the circuits are all in parallel? I am talking in relation to a L/N - E test. If Rt = global resistance for whole CU and R1, R2, R3 = L/N - E resistance for each circuit then am I right with the following: 1/Rt = 1/R1 + 1/R2 + 1/R3 So...
  7. P

    Low N/E insulation resistance

    Hi all, Just installed a brand new radial circuit for the upstairs sockets with Prysmian 2.5mm T+E, around 21 metres in length. When testing the insulation resistance of the circuit upon connection to the consumer unit, I seem to repeatedly get around 49 Megohms when measuring Neutral to Earth...
  8. S

    Quinetic controller ok with 500v insulation resistance test?

    Hello Everyone Hopefully the title is self explanatory. Or should I disconnect it for the test?
  9. A Basic Understanding of Voltage, Current and Resistance.

    A Basic Understanding of Voltage, Current and Resistance.

    An easy to understand lesson in Voltage, Current and Resistance for electricians. Learn about the basics of voltage, current and resistance in this video tutorial.
  10. R

    Insulation resistance check

    Hi - I have a Warm-up underfloor heating system. And it's stopped working. I did a basic resistance check - and clearly there's a problem (shows just 18ohms when it should be nearer 200). Warmup have said they can send an engineer around to lift a tile after doing a thermo heat check...
  11. T

    USA Resistance in a Volt meter

    Most meters today I understand are multimeters but I am only interested in the volt meter circuitry. The reason I am asking this is because the volt meter seems to only register voltage across a load and not on a plain conductor such as the neutral circuit. In my limited experience and...
  12. SparkySy

    aemc ground resistance tester 3705

    Hi to the knowledgeable collective, I recently was given one of these clamp meters for helping a friend out, however upon researching its uses it looks like it's for testing ground spike or plate resistance. Has anyone used one of these and do you have any guidance in their use? I found the user...
  13. D

    resistance problems 2002 jaguar S type

    Hi bit of a strange one as load is put on my electrical system the resistance across body earth increases if I measure negative battery lead resistance it rises from 0.1 Ohm to about 10Ohms Any ideas how to fix Cheers Dave
  14. E

    Insulation Resistance Results

    Hi, I’d like some clarification with regards to insulation resistance results I’ve got. Carrying out initial verification on a new ring final circuit. New cable, 9 new MK double sockets. r1 - 0.43 rn - 0.42 r2 - 0.68 R1+R2 - 0.28. Carried out insulation resistance test: L-N - >2000 MOhms L-E...
  15. W

    Body’s resistance with mcb only

    If there’s 230v and the body’s resistance is high .. Meaning the current will be very low but enough to kill you. Can we get electrocuted without having a 30ma rcd to stop this as the 6amp breaker will not have tripped ?
  16. T

    Insulation resistance test on length of SWA cable

    Doing new supplies for a school new Shneider 3 phase & N MCCB panel board. 50mm 4 core SWA one end made off in the board earth fly lead from banjo to earth terminal. The other end gland made off in gland (fly lead not made off yet) 3 phases and neutral just hanging there. Done installation...
  17. Ewi

    Current draw discrepancy

    Hey all. Im new to this forum. Seeing how limited d web is to rectifying any electrical queiries, i thought i might find this useful. I am a warranted electrical domestic licencee. (Based on IET) and possess a Higher Diploma in Electrical Engineering. I live in Malta (EU) which uses a UK...
  18. Tom Crabbe


    Hello, has anyone noticed in the new GN3 that any reading below 20 Mohms now has to be investigated or is this a printing mistake as it used to be 2Mohms? Thank you Tom
  19. G

    leaking resistance _0,450 Megaohm

    Hello, I recently encountered a problem with a washing machine. The washing machine tripped the RCD during its operation . I visited the place, uncovered the metallic parts of the washing machine and I searched for the current leak. I measured a leakage of 0,450 Megaoghn between on leg of the...
  20. Bobby34

    Insulation Resistance testing method

    Good afternoon, apologies if this has been covered before i've not long joined so gradually finding my way around. I have my Part P assessment coming up on a new installation and would like to hear some opinions on how people carry out their IR tests. In guidance note 3 it gives an example of...
  21. J

    Insulation Resistance...

    I am just working through my understanding of the insulation resistance test, and I want to find out the best way to do the combined Live-Earth test where the Line and Neutral conductors are connected (joined, or however it is best described) through one probe of the tester, and the other probe...
  22. N

    insulation resistance test on shower circuit with neon isolater

    On a new install of a shower circuit, with a neon isolater, is it better to use choc blocks to bypass neon isolater or would it be ok to just test live-earth (live being neutral and live combined) and miss the live-live test? If testing just live-earth, would you write it down in details of...
  23. naylorpd

    Insulation resistance test issue

    Back in 2013 I had a Domestic Electrical Installation Condition Report done on my rented property - nothing horribly major but one thing I didn't understand... I had a C3 code for "0 ohms readings for I.R test for sockets & lighting (unable to remove all loads sockets, lighting had electronic...
  24. T

    How to bypass an RCD and carry out an insulation resistance test on a circuit

    Hi all. I'm a 4th year electrician currently awaiting to finish my trade test. (FICA in Scotland) the only parts I have to pass is the testing part and fault finding. I'm currently studying testing as this is something I have done the minimum of onsite. Could someone tell me how I would...
  25. A

    Advice Wanted - VERY High Earth Resistance Problem

    I have been doing some tests around our property here and I cannot get the earth resistance test to get anywhere lower than 1.86k, even started tested now up to 30 meters away from the property and still cannot get any lower readings. Any advice would be greatful. Kind Regards James
  26. TonyJohnson

    Can Metrel EasiTest carry out Earth Rod resistance test on TT System?

    Hi, I have a truck container cafe with a floating generator for power. I am fitting an earth spike to the generator and also an earth spike to the steel container. I then need to measure the TT system i have created but i only have a Metrel easitest.. Will the tester do the job and if so how do...
  27. M

    want to complete nvq on the path of least resistance !

    I have everything except nvq and am2.Maybe half of photo evidence for portfolio.What are the best companies to go for that will do most of the work for me. I know I have to get the photo evidence.Its putting it altogether and time.i am doing the nvq at college and its begining paid for but to...
  28. N

    Insulation resistance - strange readings

    Im getting some strange reading on a new circuit(ring main) ive installed and i was wondering if anyone else had experienced the following. insulation resistance at 500v on L-N is >500mQ (which is fine) then insulation resistance between N-E starts at 400 then climbs to 500mQ then insulation...
  29. J

    Help working out resistance and supply current please.

    hi, I’m doing some revision and I can’t quite understand working out the resistance of a circuit or the supply current. Could some one please help and explain how it would be done please? I have attached a photo of the network and the question. Thanks
  30. S

    NO switch insulation resistance failure

    How often do we usually have insulation resistance failures on an NO switches leading to unexpected starts?
  31. B

    3 Phase Insulation Resistance Test on motor & TP & N skt help

    Looking for some advice on how to carry out a IR test on a 3-phase motor and a TP & N skt, these are parts of a module I have failed on a test and am looking to see where I am going wrong and what the normal procedure for carrying out this test would be?
  32. I

    Temperature probe with 110k ohm resistance!

    Hi all I have an electric underfloor heating system in my bathroom with a Timeguard TPT88 controller: (TPT88 - 24 Hour/7 Day Multi-Programmable Thermostat | Timeguard - The system as...
  33. MarkRibbands

    Insulation resistance failure on rubber flex. Why?

    Two years ago I installed some garden lighting, using u/g SWA to Wiska boxes, then 3-core 0.75mm rubber flex downleads from each LED fitting. This week the 30mA RCBO kept tripping. I assumed a luminaire fault, or moisture in a Wiska box, but no. It was leakage across all three cores of one 10m...
  34. B

    Insulation resistance testing

    Hi have AM2 next week and just need some help, 3 phase TP+N board, two way and intermediate lighting circuit with 3 switches obviously and one light, doing a global IR test, the lighting circuit say is on L1, so I’m testing all other circuits at once too do I have to switch my switches for every...
  35. Strima

    CSA and resistance of 20 & 25mm Steel Conduit

    Can anyone point me in the right direction to find out the CSA and resistance of 20 & 25mm steel conduit? It's for part of my 2396 project where I'm using the conduit as CPC, I'm happy enough with the calculations I just need some numbers to work with. I've tried various manufacturers websites...
  36. J

    Resistance Level 2 - HELP NEEDED!!

    hey, I am currently completing City & Guilds level 2 and stumbled across the below questions and scratching my head... 1. Electric Fire element has a length of 10m, a cross section area of 0.5mm2 and resistance of 50 ohms - calculate resistivity of material used. Thanks
  37. M

    No resistance Circuits

    Hi guys, How do you use ohms law on a circuit with 0 resistance? So, assume there is 10Amps and 0 Ohms on a circuit, how would you find the voltage? (E=IR?) Also assume you have a circuit with no resistance on it, where would be considered the return path? Like the potential difference I mean...
  38. PLW

    Cables with thermosetting insulation (XLPE cables)

    I understand that XLPE cables operate at a maximum temperature of 90c compared with 70c for PVC insulation. What I don't understand is why the increased temperature permits a reduction in conductor size if XLPE insulated cables are used in preference to cables having PVC insulation. If the...
  39. M

    Grounding Question

    Hi guys, I'm trying to better understand how grounding works. I got the basic idea of it, but still have a lot of questions about it. K, so from my understanding, if you touch the neutral bar on a service panel you will not get shocked (because it is grounded). But why do you get shocked if you...
  40. M

    Resistance per meter of armour

    I know it's late and the lap dances are still open , so i will wait till tomorrow for any replies . Does anyone have resistance per meter tables for steel armour 90degree thermosetting ,can't find it anywhere . Ta
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