disconnection

disconnection

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  1. P

    How is 0.2s disconnection time met on TT?

    Hi all, studying for 2391 and confused on disconnections times for TT systems Now I’m comfortable understanding the disconnection times for TN systems that need to be met which is 0.4s and because the Zs will be low enough to cause a high Ipf to cause the MCB to operate within 0.4s… also from...
  2. O

    40A shower disconnection time

    Bathroom with an electric shower wired to the latest regs with a 40A MCB and RCD protection. Is the disconnection time 0.4s or 5s. Looking at the regs it states fixed equipment up to 32A is 0.4s so everything after that unless it has a socket outlet can be 5s, but its a bathroom where...
  3. B

    Correct OCPD for disconnection times.

    Simple question (or so I thought) What would be the Correct OCPD to achieve correct disconnect times for a 200amp sun-main with ze of 0.26 tncs. What are everybody’s thoughts??
  4. newfutile

    Rcd disconnection time on TT

    On a TT system the rcd must operate withing 0.2 seconds for many circuits. Why when we test rcd's does it not say 300ms for TN systems or 200 ms for TT systems?
  5. Readytorum

    Disconnection under ADS

    Hi. I'm currently doing my design project and have submitted the first draught I've managed to correct most of my feedback but am struggling with question 5, Determine, for one of the fridges the minimum possible CSA area of CPC which will satisfy the requirements disconnection as ads under...
  6. C

    2 Way light switch disconnection

    Hi all, I have a 2 way light switch in the main bedroom for the ceiling light (a wall switch and pullcord). I'm wanting to install LED strip lighting in a corner profile around the perimeter of the room between the wall and ceiling and the pullcord mount is in the way, I don't ever use the...
  7. T

    Grid tied inverter disconnection voltage in UK?

    hi , i have been googling eg "grid tied inverter disconnection voltage in UK" but no luck Does a grid tied inverter disconnect of mains is outside 230V+10% and 230V-6% ? And does it take 4 minutes to reconnect?....ie, it waits for mains to come into range again, and then assures its been in...
  8. H

    Win10 always have WiFi disconnection problem

    Win10 always has a WiFi disconnection problem, restart the computer to reconnect, how to do?
  9. C

    Disconnection device

    Do I need a disconnection device (fcu or switch) between the supply from the mcb to a Heat Recovery ventilation system? At present there is only a multi position signal controller switch (off, timed, auto, manual etc).
  10. C

    Disconnection time extended to 63 amp circuits

    Does anyone know why the 0.8 and 0.4 second disconnection time requirements are now extended from 32 amp circuits to 63 amp receptacle circuits? Is this because the supply sources are getting stronger?
  11. C

    Disconnection Time for IT system

    What is the max disconnection time for an IT system? I think it would be shorter in that an MCB would only be triggered after a fault on two individual circuits hence double the loop impedance?
  12. C

    Confused about Zs 5 second disconnection time

    Running some calcs I'm confused about what Zs to use when calculating 5 second disconnection times. In circuits with 1.5mm2-4mm2 cable a fault doesn't seem to pull the voltage down much at the trafo terminals so from an ohms law perspective the current magnitude reflects simple V/(R1 + R2)=I...
  13. S

    Pv install disconnection.

    A job entails isolating and moving pv 1 way cu and meter from 1 wall to another.Is there a best practise order of switching off and on DC and AC Isolators for the system to avoid damage to the inverter,which is in the loft.Thanks for any advice. Regards,S
  14. 0

    RCD disconnection times!

    Hi all, just a quick one regarding RCD disconnection times. So for non rcd protected circuits disconnection times of 0.4 / 5 seconds and 0.2 / 1 second for TN + TT final and distribution circuits. RCDs (fire / fault protection) usually 300ms at rcd for rated current. (differs when s type)...
  15. D

    0.4 seconds or 5 seconds

    Just a quick question. This might sound like a stupid question so apologises. I'm slightly confused with the regs 18th edition when it comes to disconnection times. So I was taught in college that in the 17th edition that when a circuit is less than 32A then the maximum permitted time is 0.4...
  16. B

    Disconnection times not met

    Three questions haha 1. 160A MCCB the max Zs for this particular switch is 0.25 ohms all tested and I’m getting 0.44 ohms its a 95 SWA outgoing which feeds another panel which has its own outgoing circuits would I be right and say that would be a code 2? As I can’t meet disconnection time on it...
  17. C

    Disconnection Time Requirements?

    Why do circuits 32 amps and under require a 0.4 second disconnection time at 230 volts, but circuits over 32 amps are legally allowed 5 seconds? 115 volts for 5 seconds is enough to cause injury to the human body.
  18. Mark Wright

    Disconnection Times Again! Fig 3A4

    Looking at Fig 3A4 Type B 60898 unless I'm getting it wrong once we In*5 our device there is no way of telling if our disconnection is 10s or 0.1s unless im missing something although this seems quite important??? as our Disconnection time needs to be at least 0.4 seconds and for doing our...
  19. D

    18th edition RCD max disconnection times!!

    Hi all. I am seeing different figures here all over the net, table3a (p363) states a 30ma RCD has a trip time of 300ms max. So at 5x is the maximum 60ms? I seem to recall 200ms and 40ms for a 30ma and these are the figures I am seeing over the net... Please I just want the correct figures for...
  20. C

    Maximum Disconnection Times

    What is the reasoning behind having a 0.8 disconnection time for up to 120 volts Uo, but it then jumps to 0.4 seconds as soon as you go over it? Wouldn't it be better 0.8 seconds for 150 volts Uo and under, 0.4 seconds 150 volts and over Uo?

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