Discuss 0.12 ohms Suppliers ZE in the Periodic Inspection Reporting & Certification area at ElectriciansForums.net

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robbo777

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Hi

Just completed a rewire and doing all the testing but when I come to the External loop impedance I'm getting 0.12 ohms. I've never had a reading this low before, is there something I'm missing or is this possible?

And I have no parallel paths to make the reading lower either

Many Thanks
 

widdler

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there should really be no reason for concern with this value. As long as you've measured it properly.

do you have a reason to believe it should be higher?
 
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robbo777

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there should really be no reason for concern with this value. As long as you've measured it properly.

do you have a reason to believe it should be higher?
The only reason I'm asking really is that I've never had one this low before, I think the lowest i've had before this was around the 0.6 mark, so just making sure really, i'm 100% sure I'm measuring it right
 

widdler

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Well its relative to the earthing system and proximity to distributors supply transformer (where their reference 0v earth reference point is obtained). the closer you are, the lower the resistance for the earth fault loop.

With never having read a value below 0.6 ohms before, this would suggest you most oftenly work on TN-S systems?
 
M

moospark

Had 0.08 aswell, on my first NIC assesment! looked at the assesor and said sorry, but thats what the meter says, yup, substation 30 metres away. Passed
 

somersetsparks

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I've had 0.00 a few times on domestic, transformer in the back garden! Very low Ze's are common on industrial sites with there own 11kv trannys
Most seemingly TNS supplies achieve below 0.15 round are way leading me to believe that its only the short leg of cable to the property that remains TNS, it must have had new mains run in underground and PME'd
0.6 is high and in 1000 tests I have never seen one that high (apart from TT).
 
E

Engineer54

tested a TT the other day and got 35 ohms which was good as the rod was a twig!
Test it again when the grounds frozen or dried out!! I can assure you you won't see 35 ohms then!! You could even see that 35 ohms with a nasty zero added to it...lol!!

The amount of rain you have had these past couple of months or so, i bet there are many electricians patting themselves on the back after testing these twigs...
 

Guitarist

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Hi

Just completed a rewire and doing all the testing but when I come to the External loop impedance I'm getting 0.12 ohms. I've never had a reading this low before, is there something I'm missing or is this possible?

And I have no parallel paths to make the reading lower either

Many Thanks
Have to agree with the others. Nothing strange at all about 0.12
 

Deleted member 9648

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Test it again when the grounds frozen or dried out!! I can assure you you won't see 35 ohms then!! You could even see that 35 ohms with a nasty zero added to it...lol!!

The amount of rain you have had these past couple of months or so, i bet there are many electricians patting themselves on the back after testing these twigs...

35ohms or 350....with 100ma S type or a 30ma, or both, it'll still disconnect within 0.2s
Carry on patting yourselves on the back guys.
 
E

Engineer54

35ohms or 350....with 100ma S type or a 30ma, or both, it'll still disconnect within 0.2s
Carry on patting yourselves on the back guys.
Fool!!!

So now your telling us not to even bother with ensuring ''Stability'' in a TT installation now are you??
 
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