Zs

[studentspark]

6 mm cooker circuit. Zs reading is higher than maths would suggest.


With an R2 Lead

R1 = 0.01
R2 = 0.07

R1+R2 =0.09

Run About 10 m max

from TLC website - mohm/m

3.08 / 1000 = 0.003 x 10 = 0.03

7.41 / 1000 = 0.007 x 10 = 0.07

pretty near

Ze 0.11

Zs 0.60

Any suggestions on why is Zs so high?

Its still within range, but is it something I should be overly concerned about.
All connections tight

Any

 

[riveralt]

I assume that you took into account your tester/cable resistance by nulling.
Could be a poor test connection at the test point - which is .. ?
Could be a loose connection on the circuit?

 

[flameport]

How was Zs measured?
If on a 'no trip' setting, then you can expect the results to have a significant error.

 

[securespark]

Soft Zs tests give a significantly higher reading.

Next time you're at a property with no RCD protection, try both Zs tests. The soft test will be significantly higher.

 

[ricicle]

Agreed - 'no trip' Zs tests nearly always gives inaccurate results in my experience.

 

[sparkticus]

The hate those low current readings, they take ages on most instruments, the repeatability is lousy and they are rarely very accurate.

If I had my way I would bypass the RCD and take a reading at full current


Although often negligible on fixed wiring don't forget that we are talking impedance during an instrument test VS DC resistance for R1+R2

Fixed wiring is not without some reactive components