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resistance

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  1. P

    The subatomic concept of amper, after hitting a resistance.

    I have a fundamental question about the current My question is: why after hitting the protons of a resistor and thus reducing the voltage and the speed of electrons; (voltage is the distance between the electrons which the distance is smaller than the balance between two electrons which do not...
  2. S

    Please help me with this Capacitor, SCR, low resistance coil problem!!

    I want to discharge capacitor in micro seconds, In order to to that I used very low resistance coil but When capacitor is discharged, SCR kinda blow up, meaning the positive & negative got connected together because of low resistance. What can we place in negative terminal to make sure that...
  3. S

    Low insulation resistance and tripping circuit breaker

    I've just done an insulation resistance test between line and earth and got 0.0 Mohms for most circuits. Obviously this is an F1, but what I don't understand is why the CB doesn't trip. Is the answer that the resolution on my tester isn't high enough? So I could for example have 0.049Mohms and...
  4. J

    Insulation resistance on modern installations

    On initial verification of new installations I have been having a hard time with insulation resistance. With RCBOs, fixed LED luminaires, intelligent dimmer controls and other sensitive equipment now the norm on almost all installations how do we overcome this and still carry out effective and...
  5. D

    UK Low Insulation Resistance Test

    Hi guys, Hoping someone can clarify some things here. I had a socket replaced in my kitchen recently and as part of this, the electricians did an Insulation Resistance test and told me the reading was very low at just over 1 mega ohms. They advised me to basically rewire the ring (at...
  6. P

    Low resistance fault replicated on a made up rig

    Possibly a daft one this lads but any insight welcome. Have set a dummy rig up at home and am trying to replicate a low resistance fault on a ring main. No prob getting off scale high and zero readings but anyone think of a way of creating a low but not zero reading.
  7. h.abrar94

    How to calculate the resistance of steel armour under fault conditions 70 oC for CSA 95mm2

    Hi All, hope your all well. I was hoping if I can please get some advice in regards to SWA. In Particular using SWA as CPC. Cable size 95mm2 I have a table for SWA which shows various information, in the last two columns it shows the "resistance of steel armour under fault conditions at 70...
  8. A

    Max water bond resistance

    Hi all so I have a situation where a client is moving and they want the db changed for selling. Db change is easy enough as is running a bond to gas which is currently missing. The only issue is that the last eicr said that the water wasn't bonded. It would involve major works (tiled floors and...
  9. mak

    Insulation resistance test on a ring final circuit

    Might be trivial question. My understanding is that we test on either leg of the ring since both legs make up a radial, but some say they test both legs at once, i.e. LL to NN, it would make sense if the other leg is not insulated since this is a live test, but I don't see why not if the other...
  10. N

    earthing scheme suitable for worst/large value of soil resistivity in order to get earth resistance value below 5 ohm?

    i don't the exact value of the soil resistivity as no survey of soil sample is carried out at the site .However Copper earthing electrode 50mm diameter of 2.5 m is driven where its circumference were filled with chemical compound power to the height of rod and earth resistance was found to be...
  11. happysteve

    What would give a low N-E resistance (at DC), but not cause the RCD to trip?

    I'm familiar with RCD spurs giving readings of 0.1 to 0.3MΩ when testing insulation resistance (L+N tied together to E), but what would give a reading of about 65Ω (when tested with "low resistance ohmmeter" i.e. continuity setting) N-E? On a lighting circuit - N isolated from other N's...
  12. wsoppitt

    Insulation resistance issue.

    This is a new 1 on me. Testing a ring final circuit within a timber outbuilding. All clear on insulation resistance with socket fronts connected but not screwed into metal back box lug. As soon as I connect any of the plates to the back box I'm getting around 16megohm between n and cpc. When...
  13. M

    What should be the minimum resistance required between 3 phase and grounding (connecting wire to earth)

    Hi I am new to electrical engineering. I want to measure the 3 phase voltage near the water pumpset motors. I have connected phase lines to earth through a diode and six 1 mega ohm resistors (measuring the voltage across resistor). The same earthing wire is connected to ground in my dc circuit...
  14. J

    PAT testing 32A cable

    We have some 32A extension leads that range from 5m to 20m, I'm struggling to find what the acceptable values are for the resistence test. The PAT tester has a built in calculator, but that only goes up to 4mm cable, this is using 6mm. Where can I find the information I need to get the pass...
  15. M

    How do i calculate missing resistance readings in a parallel circuit using R1 and Rt

    Hi I am a current student studying to become an electrician and a question has thrown me. I'm wondering if someone could help, there is a question on one of my home work books. "complete the following table assuming the resistors are connected in parallel?" the example I will give is R1 is 120...
  16. E

    Insulation resistance check on LED fittings

    Hi, Do I need to disconnect LED fluorescent fittings when doing an insulation resistance check? Thanks
  17. M

    What are the implications of a failed Neutral - Earth insulation resistance test?

    Greetings! Newbie here! We have 3 phase installation in our Lighting dimmer rack. During Insulation Resistance testing on Earth-Nuetral, readings was 0.33Mohm on 500v test. What causede the failed test and how can I troubleshoot? Thank you! Markus
  18. B

    Insulation Resistance Calculation

    Hi, I have an engineer who is completing his 2391-52 exam tonight and he has been told one of his mock questions was wrong, I have completed the working out myself and came up with the same answer as him, so either the paper is wrong or something has literally left my mind!! "Determine the...
  19. G

    Insulation Resistance Testing

    Should I remove all the loads when testing between live and neutral?
  20. J

    Acceptable TT earthing resistance for EV point

    I understand that some vehicles do a check on the earthing resistance before they allow themselves to connect to the charging point, so irrespective of whether the earth resistance is in line with the regs, it may not be 'acceptable' to some vehicles. Does anyone know what value of resistance...

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