Ze.pefc.psc testing.

[schoe]

Hi all just a quick question carried out all of the above tests yesterday and got the following results

Ze . Tncs system 0.18 which is fine
Pefc . 1.1ka
Psc . 1.6

Carried out the same tests today and got these results

Ze 0.28 again fine
Pefc. 845 amps
Psc 1.1ka

Can anyone tell me why these readings are different and does it matter as they are all still acceptable reading for the protective device.

Thanks chris

 

[scotsparky]

are you sure its a TNCS system? Have you disconnected all bonds and isolated load?

 

[Deleted member 26818]

The discrepancy could be due to fluctuations in the supply voltage.

 

[Guest112]

does that mean that due to fluctuations an installation could fail so it should be tested a few times before contacting the DNO?

 

[schoe]

Yeah defiantly a tncs system, and yep disconnected all bonding as that was what I originally thought.

 

[alli]

Could it be due to how much power had been drawn before testing. If day one nothing had been on, then the conductors would be cool and resistance low, on day two if there had been a high load on the conductors prior to testing, the heat in the conductor may create a higher resistance?

 

[Deleted member 26818]

I would not consider contacting the DNO, untill I had obtained a number of consistant measurements.
To be honest there are a number of reasons why you could have the discrepancy.
Poor connections of the probes, loads not disconnected, voltage spikes, voltage lows. Possibly even an increase in the capacitive reactance due to loads on the communal cable, from other installations.

 

[needasparks]

I would not consider contacting the DNO, untill I had obtained a number of consistant measurements.
To be honest there are a number of reasons why you could have the discrepancy.
Poor connections of the probes, loads not disconnected, voltage spikes, voltage lows. Possibly even an increase in the capacitive reactance due to loads on the communal cable, from other installations.

Or more likely, some's not learned how to zero their meter.

 

[Deleted member 26818]

Now now, I was trying to be nice.