possible to have zs lower than ze?
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Lee,
In this case how would you know?
In this case how would you know?
PC Electrics
Well-known member
possible to have zs higher than ze?
Am I missing something here? Surely Zs will almost always be higher than Ze?
Am I missing something here? Surely Zs will almost always be higher than Ze?
correct my ze value will not be ze but? a proof of good earth only?
---------- Post Auto-Merged at 21:27 ---------- Previous post was made at 21:26 ----------
yes pc almost but i think i have a scenario
edited title pc
---------- Post Auto-Merged at 21:27 ---------- Previous post was made at 21:26 ----------
yes pc almost but i think i have a scenario
edited title pc
NO, Zs can indeed be lower than Ze,
not normally by much though,
are we talking about a normal TN situation here?
in TT it will often be much lower, if you read Ze or Zs and not Ra, this is why an Ra test should be carried out.
not normally by much though,
are we talking about a normal TN situation here?
in TT it will often be much lower, if you read Ze or Zs and not Ra, this is why an Ra test should be carried out.
would you then have a situation of Ze/Zdb ?
not always. metallic service piples will lower zs, possibly even to less than that of Ze
what supply though Lee?
TN ?
---------- Post Auto-Merged at 21:31 ---------- Previous post was made at 21:29 ----------
sorry Lee, missed that, it could well be a little lower, and esp if industrial, you will have a load of metalwork (possibly) going to earth that will drag your readings down,
perhaps by quite some amount,
something that I couldnt quantify TBH.
TN ?
---------- Post Auto-Merged at 21:31 ---------- Previous post was made at 21:29 ----------
sorry Lee, missed that, it could well be a little lower, and esp if industrial, you will have a load of metalwork (possibly) going to earth that will drag your readings down,
perhaps by quite some amount,
something that I couldnt quantify TBH.
Lee can you please answer my Q?
What are you basing your Ze on?
What are you basing your Ze on?
I have had lower Zs than Ze on many domestic occasions mainly due to the metalic pipes bringing down the resistance.
Yes Zs can be MUCH less than Ze (not correct symbols but as usual don't know how to get them on the forum and it seems that we all know the meaning.
What is the issue?
What is the expected Ze why are you questioning it?
What is the issue?
What is the expected Ze why are you questioning it?
Yes they can MUCH lower!
BTW it's impedance as it's a.c.!
BTW it's impedance as it's a.c.!
the LINE IS part of the loop test,
the clue is in the wording,
LOOP impedance,
the line is a part of the Ze reading, the only time it isnt is if you are doing an Ra on TT ,
Im not sure, but have you grasped the idea of these readings and what they represent?
EDIT, cos I said resistance too,
the clue is in the wording,
LOOP impedance,
the line is a part of the Ze reading, the only time it isnt is if you are doing an Ra on TT ,
Im not sure, but have you grasped the idea of these readings and what they represent?
EDIT, cos I said resistance too,
^^ so where did that come from?
its not added to it, it is an integral part of it.
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