impedance | Page 7

impedance

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  1. M

    Impedance, Reactance, Resistance

    Hi, I was just wondering if anyone out there could explain how to calculate the impedance of a circuit containing combinations of the above. For example Series Circuit containing 6 Ohms resistance and 8 Ohms Capacitive Reactance. Calculate impedence?? Thanks in advance. Matt
  2. B

    High impedance on working RCD circuit???

    Hi there, I'm a new electrician with ELECSA & C&G 2391 to my name & i've now been left very confused, hence the post! After adding a spur to a ring main i was doing a IR test on 250v bcus i couldn't be sure i had plugged everything out & i kept getting hardly any resistance. So i...
  3. W

    Earth fault loop impedance reading on TT System in domestic premises

    Hi All , I am new to this forum but am an industrial electrician (20 years) but have been using my Robin KTS1620 Multi tester in my house to do a few tests as i am considering returning to partp work as my industrial work is quiet. The house is supplied by a TT System through a 100mA RCD. I...
  4. E

    Max Loop impedance 1.44 or 1.16

    The Big Red book states 1.44 ohms for a 60898 / 61009 32a B rated breaker / RCBO The GN3 staes 1.16, I know this is allowing for temp rise on the faulty circuit but what do I put down on the Domestic installation cert, 1.44 or 1.16, according to Harry Hill there's only one to find out...
  5. K

    RCBO Max Earth Loop Impedance Readings

    Hi all, This is my first post on this forum, so please be easy on me.;) We currently have new Merlin Gerin consumer units installed within Aberdeen College, and looking at table 41.3 b the eli readings should be 0.72 minus rule of thumb. This fails most of the existing circuits. When i...
  6. S

    High Earth Loop Impedance

    Dear All A mate of mine recently asked me to look at his installation. It has been wired to the 17th edition and all looks kosher, but when I carried out some testing I discovered that it had High impedance values. I disconnected the Main earth that had been connected to an earth clamp, attached...
  7. S

    RCDs and high loop impedance

    Hello everyone I was wondering if it was possible in a TNCS system to add an RCD to a final circuit with a loop impedance exceeding the values stated in tables 41.2 - 41.3 to ensure fast enough disconnection during an earth fault. I had thought it was but if so why are RCBOs subject to the same...
  8. E

    Maximum earth loop impedance

    Table 41.3 gives the maximum earth loop impedance on a type B 32a breaker to 60898 as 1.44 ohms, the testing schedule on the domestic cert asks maximum permissble loop impedance, in the test and inspect notes I seem to remember that you are required to write the full 1.44 but I'm sure that you...
  9. D

    Circuit Impedance

    Taking over a building and starting to get PIR's for handover. They are NICEIC styley and under Circuit Impedence they have three columns for Ring and two for 'All Circuits'. The tester has filled in all columns for every cct but they don't make much sense, eg, 4mm line and cpc, R1=0.39...
  10. D

    Help Please - max earth fault Loop Impedance value table needed urgently

    Hi everyone Would be really grateful for your help on this. I have my 1st NICEIC assessment on Monday (am bricking it) - anyhow I only have an old table & I need one like you get on the back of the proper NICEIC pads - the most up to date table. Has anyone got one they could send me so...
  11. E

    Measured Loop impedance

    On another issue how do test the loop impedance at a fixed appliance or a light, to fulfill the measured loop impedance column requirement on the schedule of tests. will the calc R1 + R2 suffice?
  12. E

    Impedance readings on a ring

    Testing a domestic ring main recently R1 end to end was .4 Rn was .4 the cpc which was probably 1mm (oldish cables 1975ish) read .2. possible reasons for this?? On another issue how do test the loop impedance at a fixed appliance or a light, to fulfill the measured loop impedance column...
  13. L

    Testing

    When using a meter to carry out earth loop impedance measurement on final circuits by disconnecting the earth conductor. Is it neccessary to check the line to neutral impedance, this should be carried out with all earths connected.
  14. tuckermot

    RCD,Rcbo tripping on earth loop impedance test

    Hi every one I have a robin 1620 multifunction meter and i am commencing my 2391 in march.My meter does not have a D,lock so when doing earth fault loop testing on circuits protected with rcds and rcbos the test current some time trips the breaker before the meter can get a reading has any one...
  15. S

    Minimum impedance protection & voltage balance protection

    What are minimum impedance protection & voltage balance protection for Sync. Genarators (turbo/hydro)? Please explain
  16. W

    Earth Loop Impedance Table 17th Edition

    Hi Guys, Here is a handy 17th Edition Loop Impedance Table. This table gives you a direct comparison with your Zs tests results and is calculated @ the 0.8 Rule of Thumb figure. Enjoy! :) Warren
  17. D

    Do you need to do continuity tests on minor work

    As Title says. On the Minor Works Certs from the IEE they dont have any boxes for continuty tests. Only insulation tests and Polarity. Do you still have to test for continunity if you are only have to fill in a Minor Works Cert where for a alteration to the Lighting or adding a new socket to...
  18. T

    Testing Voltage drop using circuit impedance

    Ok guys got my head in the 17th edition New bit in Part 6 Inspection and testing (used to part 7 in 16th) 612.14 - "the voltage drop may be evaluated by measuring the circuit impedance" :eek: managed to find the same query on another forum, and lots of views on there about how you would...

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