ZS - LOOP IMPEDANCE - WHY SO MANY NUMBERS - HOW TO CALCULATE THE CORRECT ZS - WHAT THE NUMBERS MEAN

We are often asked which ZS figures to use, and yes, it’s true that the books have different ZS numbers for the same circuit breaker. For many, especially new learners, there is some confusion over which numbers to use and what the numbers actually mean.
And it does matter which numbers are used - of course.
If we look in the Wiring Regulations book, the big brown book, we will find Zs values for the different breakers and fuses and another, totally different value is shown in the on-site guide and in the Electricians Guide to the Building Regulations. Why are there two sets of data.
But that’s not the end of the story, there is a third value, different again, in the same Wiring Regs book.
In this video we will help you to understand why we have different numbers for the same breaker or fuse and show you how to calculate the different values.
This is video number 213 and to view all our videos type in LearnElectrics all one word into the CZcams search bar.
Visit our CZcams channel where we have many more videos on a wide range of electrical topics.

[@TheNathan696969]

You're right, this was extremely helpful! Thank you for taking your time to explain it so clearly!

[@learnelectrics4402]

Glad it was helpful and thank you for watching. Dave.

[@jackpearce4936]

Great video. Recently did my 2391. We predominantly worked out of GN3. Also contains all measured Zs values. Thought it was worth a mention.

[@learnelectrics4402]

Absolutely is Jack. I should have mentioned GN3. Thanks for keeping me on my toes. Thanks for the support. Dave.

[@user-cs9ch8ey9k]

No one does it like you Dave, great video,.

[@learnelectrics4402]

Thank you, great compliments and truly appreciated, Dave.

[@brianhewitt8618]

spot on 👍

[@learnelectrics4402]

Glad you think so, thanks for the feedback Brian.

[@pauldendleguitar]

Great tutorial on these really important distinctions.

[@learnelectrics4402]

Glad it was helpful and lots more to come. Dave.

[@engmalikaltayeb3519]

You are incredible, you are amazing

[@learnelectrics4402]

Nice of you to say so. Thank you for watching. Dave.

[@abdirizakhassan1073]

Thanks Dave I appreciate you time
You are great teacher

[@learnelectrics4402]

You are very welcome, thanks for watching and supporting the channel.

[@nittaberi]

Great summary of older videos about maximum Zs calculation. Thanks! ✌️ I use raw value x 0.76. It's
simplier for me.

[@learnelectrics4402]

That works, but I need to show new starters all the calculations. Thanks for the input and the support. Dave.

[@Dog-whisperer7494]

Fantastic video as always 👍

[@learnelectrics4402]

Thank you, your support is always appreciated, Dave.

[@user-qi8tv2sj4m]

Great video. Helped a lot.

[@learnelectrics4402]

Glad to hear it and thanks for the support.

[@highgatehandyman6479]

Best tip ever is the 44 rule.
44/ in. X .8.
Really usefull when actually onsite

[@learnelectrics4402]

It works. Thanks for watching. Dave.

[@abdeldjalilarbane8814]

Great vedio well done and explained

[@learnelectrics4402]

Glad you liked it, thanks for watching. Dave.

[@abdulseaforth6930]

Absolutely!

[@learnelectrics4402]

Yes indeed. Thanks for watching, appreciated.

[@ELECTRICLIFE4U]

❤👍👍👍👍👍👍

[@learnelectrics4402]

Thanks for watching.

[@connorcurrie4434]

Is there a formula R2 = R2/R1+R2 + (R1R2 that's the measurement taken) the first R1 R2 are conductor sizes.

[@learnelectrics4402]

We often make fractions out of R1, R2 etc. to calculate other values. Take a look at the video on this link. Thanks for watching.
czcams.com/video/9DLgM8wM5xo/video.html