Ze testing

[waynelester]

hi,i have tested ze on two installation both being tns.the results are 0.08 and 0.12.these figures seem very low for a tns system.are these normal or am i doing something wrong im using a kewtech kt64,,thanks

 

[Sintra]

I have come across Ze values as low as that on a TNS before so I shouldn't worry too much. You are probably very close to the DNO sub.

 

[telectrix]

only query is: are you disconnecting the main earth from the board before testing Ze to eliminate parallel paths?

 

[waynelester]

yes and connecting live to live,earth to earth and neutral to neutral

 

[telectrix]

must be right then.

 

[waynelester]

thanks

 

[Deleted member 19807]

one other point is are you testing ze or pfc ? with my fluke ze tests between line/earth and pfc between line/neutral, you will get a much lower reading of resistance when set to pfc.

 

[Sparky Ninja]

one other point is are you testing ze or pfc ? with my fluke ze tests between line/earth and pfc between line/neutral, you will get a much lower reading of resistance when set to pfc.

Huh.

PFC.... Resistance???

Are you referring to likely reduced impedance between PFC and PSC?

 

[Deleted member 19807]

if you like, The point i was makeing in relation the the op was that my fluke gives a Ohms reading when set to ze and pfc this is obviously measuring a differant fault path and if the op was not familure with testing and or his tester he may be confusing the 2.

 

[Sparky Ninja]

KT64 has a Loop setting, or you turn the dial to the PFC setting, so I doubt it's possible.

 

[waynelester]

sorry dont know what you mean, i have obtained two very low readings for ze on a tns system and was wondering if this was normal or was i testing incorrectly,also the pfc comes out at about 3.2ka which i supose is about right when calculating using ohm law

 

[andyb]

You would get a low reading like that if you were near to the sub station.

 

[Sparky Ninja]

If these are the reading you are getting then fair enough. I myself would expect a higher pfc with such little impedance.

 

[olly w]

I've had readings of 0.01 ohms quite often when testing very close to the sub so don't worry about it.