EFLI - measure or calculate?

[Billythekid]

Measure.

It is possible that your low current Continuity tester will indicate a sound connection, whilst the high current Loop Impedance tester will expose a possible weakness.

Regards

Billy

 

[Silly Sausage]

Hey calm down now LOL

What's with scousers fiddling with my posts?!?!


Live Zs every time!

 

[kingeri]

If you've proven continuity and measured your Ze, then calculating Zs is fine by me. But it actually doesn't take that long to measure, so I suppose you just get better piece of mind by doing so.

 

[MDJ]

We discussed this a day or two ago and decided to verify the circuit a measured ZS was needed, can't remember which thread it was now but it made sense afetr reading it all.

 

[Guitarist]

And that's why it's better to calculate.

Parallel paths come and go, and you have already proven you have an earth so I don't agree with you at all.

I do agree with this reasoning, and as a rule I tend to calculate. If there's a lot involved with disconnections for measuring, however, I'll happily measure.

 

[Octopus]

Time to be contraversual (if I could spell it). So I'm spurring off a RFC. I take the Zs at the "donor" socket, then do a R1 + R2 on the new bit. This to me is OK, but many would say you HAVE to do it from the board - WHY?

 

[Silly Sausage]

Time to be controversial. So I'm spurring off a RFC. I take the Zs at the "donor" socket, then do a R1 + R2 on the new bit. This to me is OK, but many would say you HAVE to do it from the board - WHY?

Depends on how long the spur is...





having already verified the original cct.

 

[SirKit Breaker]

A brave man to disagree with SirKit Breaker!

He's entitled to his opinions.

Cheers………….Howard

 

[Sintra]

Always measure the Zs as this is the only test that verifies the complete circuit. To throw in my scenario from the other day with a protective device with a high internal resistance.

 

[Guitarist]

So as the MWC/EIC needs an R1+R2, how would you arrive at that? It shouldn't be done as Zs-Ze due to parallel paths. Measurement is great for circuit confirmation, but for the paperwork?

 

[monkeyelectric]

It is all well and good calculating it, but it doesn't prove that you have an earth, testing it does. I know calculation is acceptable, but measurement is better if you think about it, and although Ze =Zs +(R1+R2], a measured result will always be a bit lower (or should be) due to parallel paths, and the current that the tester is forcing around the circuit.

Cheers……………..Howard

I too disagree with SirKit! Its Zs = Ze +(R1+R2) :devilish:

 

[telectrix]

just as a slight digression, yesterday was testing an existing efli on a lighting circuit. using 1553 on no-trip. MFT came up with "trp" and the RCD had, in fact, tripped. i can only assume a poor lead connection. any other thoughts? the RCD had been tested and gave ideal results on both x1 and x5. ( 34mS and 12mS).

 

[Guitarist]

just as a slight digression, yesterday was testing an existing efli on a lighting circuit. using 1553 on no-trip. MFT came up with "trp" and the RCD had, in fact, tripped. i can only assume a poor lead connection. any other thoughts? the RCD had been tested and gave ideal results on both x1 and x5. ( 34mS and 12mS).

I've had this before on my 1730. Usually existing leakage+test current pushes the RCD past it's limit (usually around 22mA on a 30mA unit).

 

[telectrix]

thanks. will go for a ramp test on that RCD with circuits connected.

 

[Tridentsystems]

Fill Certs in at end of week , guess and duplicate thirty times