Whats the difference between Ze------

[d1scv]

One of those questions that's hard to admit I am just not sure of !

You assume that you've just forgotten- when the truth is you never really grasped it !

What is the difference between Measured Ze and External Earth Fault Loop Impedance.

And a Merry Christmas to you all, Tony

 

[ryanryan]

none

 

[earlelectric]

ze is external. zs is external and internal impedance.

 

[d1scv]

none

What caused me doubt myself, is that an installation cert. I am doing shows it as 2 seperate boxes requiring 2 seperate answers.

ze is external. zs is external and internal impedance.

Whilst your answer appears off at a tangent- it isn't.

I.d always assumed that Measured Ze- was in fact Zdb- the true reading that makes your equation work.

I,d assumed that External Earth Fault Loop Impedance was the reading obtained using the supplies earth only- i.e. seperated from possible parallel paths.

 

[diditrain]

Is one not what the suppliers will specify if you contact them i.e. 0.35 TN-C-S, 0.8 TN-S AND 21 for TT.
The other one will be what you actually measure

 

[Notsosmart]

Is one not what the suppliers will specify if you contact them i.e. 0.35 TN-C-S, 0.8 TN-S AND 21 for TT.
The other one will be what you actually measure

Spot on didtrain,these are the standard DNO quoted Ze's but i have been quoted other figures on-site from an experienced service head installer (all be it unofficially as he wouldn't put his name to it)

 

[Spudnik]

Gotta love the NIC certs