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Discuss Earth Loop Impedance Table 17th Edition in the Periodic Inspection Reporting & Certification area at ElectriciansForums.net

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WarrenG

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Hi Guys,

Here is a handy 17th Edition Loop Impedance Table.

This table gives you a direct comparison with your Zs tests results and is calculated @ the 0.8 Rule of Thumb figure.

Enjoy! :)

Warren
 
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D

DanBrown

  • Thread Starter Thread Starter
  • #2
Hi Guys,

Here is a handy 17th Edition Loop Impedance Table.

This table gives you a direct comparison with your Zs tests results and is calculated @ the 0.8 Rule of Thumb figure.

Enjoy! :)

Warren

What do you mean by the 0.8 rule of thumb figure?? What is that??
 

jeremy

-
Mentor
Arms
DO you have to point 8 of your thumbs at something?? I've got 2 and am willing to lend tham out!
 
W

WarrenG

  • Thread Starter Thread Starter
  • #4
When taking a Zs reading, we cannot use the direct measurement to compare with the Zs earth loop tables in the Regs.

We have to take into account ambient temperature (at the time of test) and the conductor operating temperature. Both have an effect on the resistance. There is therefore a 0.8 rule to apply for your max Zs reading.

Example:

Regs book Page 49, Table 41.3, Type B BS EN 60898, 6A Zs = 7.67 ohms

7.67 x 0.8 Rule of Thumb = 6.13 ohms

17th Table - BS EN 60898, 6A Zs = 6.13 ohms

So the table gives you a direct comparison for your Zs readings.

Hope this helps!

Warren
 
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DanBrown

  • Thread Starter Thread Starter
  • #5
Yeah, thanks for that warren..
Where does the figure 0.8 come from? is it in onsite guide or big regs book?.
 

jeremy

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Mentor
Arms
OSG. The big one quotes the max allowed under perfect conditions then you have to adjust it by allowing for max operating temp etc. The 0.8 is allowing for worst case scenario but if your Zs is greater than the 0.8 adjusted figure it doesnt necessarily mean it has failed there are longer calcs that can be done to take into account each individual installation. Hope this is of use.
 
H

hugo

  • Thread Starter Thread Starter
  • #7
Warren

You posted a table with max eli details earlier this year. Im new to the forum, can you tell me how to get a hold of the table.

Cheers

Hugo
 
B

BigD62

  • Thread Starter Thread Starter
  • #9
hi warren
Sorry cannot find the table you describe
regards
BigD62
 
H

hugo

  • Thread Starter Thread Starter
  • #10
Thanks. I've got the tables in the Regs, but I thought that someone had taken the time to put them into another format; Word or Exel.

Just lazy mate!:)

Regards

Hugo
 

old dog

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Arms
the tables in the on site guide and guidance note 3 give the values after the 0.8 calculation
bs 7671 gives the max before calculation
have a look on page 111 table b.4
osg page 103 table 2 d
for examples
 
G

Guest 004

  • Thread Starter Thread Starter
  • #12
Hi Guys,

Here is a handy 17th Edition Loop Impedance Table.

This table gives you a direct comparison with your Zs tests results and is calculated @ the 0.8 Rule of Thumb figure.

Enjoy! :)

Warren
where is it??
and does anybody have 100% values?
These 80% values are also in the NICEEIC test book
 
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