Ze external earth loop impedance

[telectrix]

Parkinson BBC Rod Hull & Emu 70s - YouTube

 

[Geordie Spark]

View attachment 22072

Naaa it would be too obvious if I posted a picture of a fine upstanding cockerel.

Oh dear .... I just KNEW it!! :nonod:

 

[telectrix]

better watch it, geordie, she'll be running off with a cockney next.

 

[Geordie Spark]

better watch it, geordie, she'll be running off with a cockney next.

That's what you think ....... I know she hates Cockneys, so why the Hell she watches Eastenders all the time I don't know!!

 

[tidyboiler]

That's what you think ....... I know she hates Cockneys, so why the Hell she watches Eastenders all the time I don't know!!

Well there's hardly any white British folk in it anymore, so I don't feel so homesick for Brum. :shuriken:

 

[sparks1234]

Just means your damn near a local DNO distribution substation... lol!! Start worrying when you're getting values 00.4 ohms!! lol!!

Eng,
Do you mean 0.04 Ohms or even .004 ohms? (thats a lotta raisins)

 

[guest119]

Eng,
Do you mean 0.04 Ohms or even .004 ohms? (thats a lotta raisins)

Eng is still in Cyprus on hols till the 10th, sippin the oozo (spelling?).:17:

 

[Silly Sausage]

Eng is still in Cyprus on hols till the 10th, sippin the oozo (spelling?).:17:

Spilling the Ouzo, drops Ra values like a stone!

 

[Chr!s]

And, just to point out something else.... there's not really such a thing as a maximum Ze value, either, as they don't officially exist. Neither BS7671 nor ESQCR contain the mythical figures of .35 and .8 for TN systems so the DNO's are quite at liberty to deliver as they wish. The only which IS set in stone is that circuit max Zs figures have to be achieved.

Your right to a point, though take PME, their is a legal limit with regards volts. So Tx set to 250 V and a 100 amp supply PME 0.35. So 100 x .35 = 35 V

250-35 = 215 V, very close to the 216.2 V minimum(230-6%)

 

[Rockingit]

Your right to a point, though take PME, their is a legal limit with regards volts. So Tx set to 250 V and a 100 amp supply PME 0.35. So 100 x .35 = 35 V

250-35 = 215 V, very close to the 216.2 V minimum(230-6%)

Eh???? I think you need to have a think about that.

 

[Chr!s]

Eh???? I think you need to have a think about that.

Why, whats wrong with it

 

[Silly Sausage]

Also, with a TN supply, if yar Ze is too high, an Earth fault won't take out the intake fuse. (depending on A rating)

 

[Rockingit]

Why, whats wrong with it

Just in case I'm misunderstanding you...walk through it once more.

 

[Engineer54]

Eng,
Do you mean 0.04 Ohms or even .004 ohms? (thats a lotta raisins)

I did indeed mean 0.04 ohms!! That decimal point can get you into some real problems if your not careful!! lol!!

 

[Chr!s]

Just in case I'm misunderstanding you...walk through it once more.

Well on a single phase system whats the mimimum voltage.

So for a 100 amp supply, assuming a current of 100amps 35 volts will be dropped in the supply.

So if at Tx terminals we have 250v then and 35 v dropped across supply then only 215 v is supplied at the consumers service head