Zs and the 80% RULE. What is it and understanding the differences between Tabulated and Measured 

Every electrical installation should be inspected and tested before being put into service.
When it comes to testing the circuits there are so many tables of numbers and options in various electrical books.
Which table to look at, when to use certain numbers, all this can be very confusing.
What is Zs and Zs(m) and what if any is the difference.
Where does the data come from, can someone explain where it all starts and how it all becomes the numbers that we are testing on-site.
This video will show you in easy to follow steps how we get from the raw data, in fact, where to find the raw data for yourself, and how to follow the steps through to the actual numbers that you test against with your meter.
Easily learnt and easily remembered it is an essential skill for all electricians.
This is video No.61 on our RU-vid channel where we have videos on a wide range of electrical topics.
To see a full list of all our LearnElectrics videos, click on the link below
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