problems with test results

[chris butterfield]

Right i recon i have a n earth fault on a lighting circuit on that side of the red and also a crossed n on the other

I recon this is my problem hammy

Any ideas on the different zs values I'm getting from my dialog tester on the same socket chaps ?

 

[Leesparkykent]

@Loki 2.5 T&E RFC with a R1+R2 reading of 0.48 would give an expected value of 1.15 for r2 and 0.77 for r1.

1.15+0.77= 1.92

1.92/4=0.48

To work it out

0.48x4=1.92

1.92/1.67=1.15 for r2

1.92-1.15=0.77 for r1

 

[Pete999]

You said that the Ze is 0.5
Im guessing its a tns & not tncs then as its over the 0.35 Ze max



If using 2.5 (1.5) T&E

Zs 0.98 - Ze 0.5 = 0.48

4 ÷ (2.5 + 1.5) x 0.48 = 0.3

r2 = 0.3 ohms
r1 = 0.18

Roughly lol, Am i close?

You said that the Ze is 0.5
Im guessing its a tns & not tncs then as its over the 0.35 Ze max



If using 2.5 (1.5) T&E

Zs 0.98 - Ze 0.5 = 0.48

4 ÷ (2.5 + 1.5) x 0.48 = 0.3

r2 = 0.3 ohms
r1 = 0.18

Roughly lol, Am i close?

Are you answering post 3?

 

[Loki]

@Loki 2.5 T&E RFC with a R1+R2 reading of 0.48 would give an expected value of 1.15 for r2 and 0.77 for r1.

1.15+0.77= 1.92

1.92/4=0.48

To work it out

0.48x4=1.92

1.92/1.67=1.15 for r2

1.92-1.15=0.77 for r1

Thanks for clearing that.
Think i was mixing formulas up

 

[Loki]

Are you answering post 3?

Just noticing the Ze was above 0.35 for tncs & was wanting to work out expected R1 & R2 values

 

[Midwest]

I seem to recall, I might be wrong, one of our more eminent members describing a situation where a neutral earth fault on a circuit could trip an RCD that is not protected by?