Zs tests on radial circuits?

[Deleted member 26818]

I think you're short-sighted. I get 352.2Ω.
He stuck a zero where the decimal point should be.
Should be 7.41 mΩ/m.

 

[telectrix]

o.37 then. add o.15, Zs=0.52 ( multiply for the correction factor allowing for stretching due to the fact that the cable was 3" too short to terminate, )

 

[antimatter]

humm, bet Kewtech arnt happy then, after developing their extremely overpriced light fitting test thingys!!

They're not too badly priced I thought, I picked up the Lightmate (BNC) and socket (banana jack socket) both for £20 from Denmans

 

[gpz900jim]

on my assessment, the nic man said that the nic would rather you do a ze and add it to an r1/r2 to get zs, its less live testing

 

[Sparky Ninja]

on my assessment, the nic man said that the nic would rather you do a ze and add it to an r1/r2 to get zs, its less live testing

On this occasion NICEIC are having to stick with their DVD productions. It's up to your interpretation on what you consider best practice.
MCB's and RCD's can give off impedances that will provide a higher measured Zs than the simple calculation will prove.

I would go into the NICEIC's reasoning, however I dont have my EAW redgs in front of me so don't want to start misquoting them.


Oh and its (R1&R2) btw.

 

[Octopus]

I think you're short-sighted. I get 352.2Ω.
He stuck a zero where the decimal point should be.
Should be 7.41 mΩ/m.

How did you get 352.2?

 

[Deleted member 26818]

7041 x 25 = 176025 x 2 = 352050 / 1000 = 352.05 + 0.15 = 352.2.
Of course the correct answer using 7.41 is 0.5205Ω.

 

[Guest123]

I'm guessing he meant 7.41, as that is the value for a single 2.5mm conductor.

I'm going for 0.52ohms.

 

[Gtbadboy1]

i have worked it out to be 0.335
7.41*25= 185.25/1000=0.18525+0.15 =0.335

 

[telectrix]

i have worked it out to be 0.335
7.41*25= 185.25/1000=0.18525+0.15 =0.335

you'vge only got R1 there mate. its 7.41 x 50 for R1+R2

 

[Gtbadboy1]

you are correct mate double the length will include the R1 and R2. I must be blond

 

[Deleted member 26818]

Of course, that's without applying any correction factors.
My understanding is that you would multiply that figure by 1.2 to obtain the Zs for a 70° conductor temperature.

 

[telectrix]

either that or use the corrected value for the max.Zs (as in OSG).