they do ask for zs but without getting books out i am sure i have read that it is accepterble to calculate zs, on the nic eic inspecting and testing dvd i am sure it says to calculate if you dont have non trip on your tester.They ask for Zs though - if they wanted Ze + R1 + R2, they'd ask for it
Precisely - if you have a good reason not to test.they do ask for zs but without getting books out i am sure i have read that it is accepterble to calculate zs, on the nic eic inspecting and testing dvd i am sure it says to calculate if you dont have non trip on your tester.
When I done my 303 C&G 2330 We were told to measure the Zs at the lighting circuit by placing the probes on the terminals in the rose itself . I asked why a calculation was not sufficient for recording the result and my examiner said he wanted to see me measure the Zs has it was to do with my competence with safely working live . Fair point I suppose .TBH the only people doing zs testing would be competent electricians who know how to handle a live open CU or switch and personally i always like to do zs tests rather than calculate it where practical.
We had to use GS38 compliant leads/probes and managed to get on to the terminal were the conductor enters .I didn't think you could get GS38 compliant probes into a rose????
You haven't measured Zs.I am sorry to repeat myself but YOU HAVE MEASURED IT.Calculation means what is done at DESIGN stage i.e. taking Ze given and CALCULATING Zs by working out R1 + R2 for the circuit by length x r/mtr.
If you have MEASURED the Ze and MEASURED the r1+r2 then you have a MEASURED Zs.
It is easier to do a calculation in this case of course and probably safer if the rose is fairly high up as it is tricky although not impossible to get your probes securely on the terminals . Is a calculation the accepted way to record Zs on a lighting circuit due to the awkward nature of the terminals .I thought that'd be the only place you could get the probes in!
i tend to do live test 9 out of 10 times, but i do think the above way is acceptable, can anyone give a good reason why measuring r1 r2 and ze is no goodIt's not a calculation....It's a measurement... you measure Ze and you measure (R1+R2)
and it is an acceptable way to get your "max measured Zs"
Yes, regulation 612.9 states:It is easier to do a calculation in this case of course and probably safer if the rose is fairly high up as it is tricky although not impossible to get your probes securely on the terminals . Is a calculation the accepted way to record Zs on a lighting circuit due to the awkward nature of the terminals .
All been mentioned in previous postsi tend to do live test 9 out of 10 times, but i do think the above way is acceptable, can anyone give a good reason why measuring r1 r2 and ze is no good
Measure Zdb and add that and not Ze to R1+R2 to get Zs.i tend to do live test 9 out of 10 times, but i do think the above way is acceptable, can anyone give a good reason why measuring r1 r2 and ze is no good
You measure Ze and you measure (R1 + R2) and you add the two figures together to get your Zs for the circuit ( thats why I said calculation ) :BlushingIt's not a calculation....It's a measurement... you measure Ze and you measure (R1+R2)
and it is an acceptable way to get your "max measured Zs"
This was more where I was going by starting this thread. These days with H&S being the way it is. You are up a pair of steps trying to hold two probes in place on to live terminals with one hand and pushing the test button with the other. rayIt is easier to do a calculation in this case of course and probably safer if the rose is fairly high up as it is tricky although not impossible to get your probes securely on the terminals . Is a calculation the accepted way to record Zs on a lighting circuit due to the awkward nature of the terminals .
If you got a Megger MFT it automatically starts the test when the probes are placed on correct terminals so need need for a 3rd handThis was more where I was going by starting this thread. These days with H&S being the way it is. You are up a pair of steps trying to hold two probes in place on to live terminals with one hand and pushing the test button with the other. ray
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