CABLE SIZE CALCULATIONS - ON-SITE GUIDE APPENDIX F - AMENDMENT 2 - USING THE TABLES - MAKING CHOICES

The On-Site Guide is a useful little book, packed full of information. But sometimes, working out what it’s telling us can be difficult, and not just for new starters in the trade.
Take this question for example … a frequent question.
I’ve seen this formula in the on-site guide, what does it mean?
And it looks complicated, how is that going to help me?
In this video we will look at Appendix F of the On-Site Guide, a very useful appendix that helps you to select the correct size cable given the various installation conditions. And we show you how to use Appendix F to find the answers.
Almost everything that we do to a cable will cause it to heat up, even over-heat and become damaged. Choosing the right size cable is therefore in everyone’s interest. We show you how to make the right calculations with fully worked examples so that understanding and confidence improve.
What matters most is putting the right cable into the installation from the outset.
This is video number 214 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.

[@Chrisking85]

give this man a medal. no one is doing it like dave. thank you dave appreciate all your hard work

[@learnelectrics4402]

Wow, thanks, that is really appreciated. Dave.

[@danielteyehuago1633]

Wow! This is very informative, thanks for sharing it with us. It worth it and the best tutorial on the topic for me.

[@learnelectrics4402]

Glad it was helpful Daniel. Keep spreading the word and lots more to come. Dave.

[@ragnor56]

One of the best Elec tech sites on the web helped me understand how to wire sockets & lights into my son's ring circuit house which I had not come across before although I was competent to carry out all the work myself

[@philipekine7278]

p😮😮

[@learnelectrics4402]

Glad it helped, thanks for watching.

[@learnelectrics4402]

Thanks for watching.

[@francoistoumany3841]

Thank you Dave for helping us to remain technically minded as we appraoch each job. It's always a good reminder to give attention to how we design each circuit to make sure that it complies. As always much appreciated and keep up the good work. 👏🏾

[@learnelectrics4402]

Very welcome and thanks for the positive comments. Dave.

[@simplymiswak4010]

This video is amazing! Keep up the good work because I’m learning a lot.

[@learnelectrics4402]

Will do, thanks for watching. Dave.

[@davidpatterson1574]

Thanks Dave-informative video, and very understandable graphics

[@learnelectrics4402]

Glad you enjoyed it and thanks for the positive feedback. Dave.

[@stegra5960]

A handy tip that's stuck with me since I was told it about the < & > symbols is that the < looks a bit like a squashed L (for less).I'd never had difficulty with them but this is just saves that bit of thinking.
Also, when using a calculator, the = button is your friend. So 20÷.88= (then) ÷.725= gives the answer without the additional step or using M+ and MR.
Thanks again for your incredible content.

[@learnelectrics4402]

Excellent support. Thanks for the input, it will help many. Dave.

[@BlaqRaq]

Another great simple elegant presentation.

[@learnelectrics4402]

Thanks again, thanks for the support.

[@SuperCwiczenia]

Another great simple elegant presentation. Super @:)

[@learnelectrics4402]

Thanks a lot, appreciated.

[@brianhewitt8618]

Excellent, correct design is always very important 👍

[@learnelectrics4402]

Absolutely. Thanks for your supportive comments Brian, appreciated.

[@dannysmith2408]

great video to re-cap. thank you.

[@learnelectrics4402]

Glad it was useful. Dave.

[@kristianbarrett7215]

Fantastic tutorials keep up the good work 👍

[@learnelectrics4402]

thanks for the comments. Yes, lots more to come. Dave.

[@terietaietawa6800]

Very useful and informative video thanks

[@learnelectrics4402]

Thank you, appreciated and thanks for watching.

[@user-qi8tv2sj4m]

Very very useful. Thanks.

[@learnelectrics4402]

You are welcome, thanks for watching. Dave.

[@franciscogago5961]

Thanks for the video...

[@learnelectrics4402]

My pleasure. Dave.

[@AhmedMohammadali-pn3ud]

thank you easy

[@learnelectrics4402]

Thank you, appreciated.

[@nohandle747]

Thank you so much!

[@learnelectrics4402]

You're welcome. Dave.

[@23sasr]

brilliant thank you so much

[@learnelectrics4402]

Glad it helped. Dave.

[@Oufg103f]

Great video, watched it twice now 😂

[@learnelectrics4402]

Great to know. Thanks for the feedback, appreciated. Dave.

[@user-cs9ch8ey9k]

Hi Dave
Can we please have a video about installing single cables for lighting circuits in steel conduit and how we prevent Eddie currents, thanks for everything mate

[@learnelectrics4402]

Its on the list. Thanks.

[@mehdikhodabakhsh-fb3ez]

Brilliant explanation .but just wondering where about in question said what reference method is that.
Thanks

[@learnelectrics4402]

It is all in the question, the data/clues are all there to work out the reference method. Have another look at the video and follow my working through.

[@mehdikhodabakhsh-fb3ez]

@@learnelectrics4402 thanks for your reply .boss page .I just have looked again you are right 👍

[@david-ip9cm]

Great vid! Quick q.. for question 1 why is the ref method C and not 100? ref method 100 mentions insulation doesn't exceed 100mm for which it doesn't as it's 50mm? thanks!

[@learnelectrics4402]

Ref method C is the starting point for the reference methods. This has the highest permissible current for a size of conductor. All the others are reductions on the Ref C figures. Hope this helps.

[@kashif4463]

@@learnelectrics4402 so do we always use ref method c for the exam questions on the 2365 203 exam?

[@grmo1875]

Thanks, another great video. Does this apply also to a ring final, wired in 2.5mm TC+E? I’m bashing my brain against this because on the one hand OSG part 7 says we can use 2.5mm cable for an I n of 32 A, and an I t 32/0.8 = 40 A; but the current carrying capacity of 2.5mm cable is nowhere near that? I can’t help thinking I’ve missed something that is written in the books somewhere that explains the case for ring finals … ?

[@learnelectrics4402]

With a ring circuit, you have two 2.5mm wires - making 5mm of conductor. That is why the figures seem higher. Take a look at this video. Dave.
czcams.com/video/6GNb1SSEjQg/video.html

[@bigbud1978]

The best !

[@learnelectrics4402]

Excellent, that's good to know. Thanks for watching. Dave.

[@Grassislong]

Hi great video. I am currently doing design project through college and i have the exact issue that you’ve stated in 14:00. my I n is greater than my I t due to the 25c ambient temperature (which is required in the spec).
my understanding is that I t should be bigger than I n, under all circumstances. so how can i get around this issue to change the values and make the calculation work? really hope you can get back to me on this 😅
many thanks Daniel

[@learnelectrics4402]

Increase the cable size, that is the best way, this will increase It. Or decrease the breaker rating to reduce In, but not always practical.

[@ashrafhalimy1619]

great

[@learnelectrics4402]

Thank you, apprteciated.

[@Sergey3023]

Smashing 💪🏻

[@learnelectrics4402]

Thank you, appreciated

[@MotherboardRepairs]

Great work 👍, I have a question what about Iz as i am getting it mixed up with It.

[@learnelectrics4402]

Iz is the amount of current a conductor can carry 24/7 under the installation conditions that affect it.

[@MotherboardRepairs]

@@learnelectrics4402 Thanks for the quick reply, I understand Iz is current carrying capacity but where i struggle to understand is when working out the formula sequence e.g
Should it be;
Iz ≥ In = It
Ca x Cg
Or
It ≥ In = Iz
Ca x Cg

[@sharifwalo4257]

Amazing

[@learnelectrics4402]

Thank you, great feedback.

[@ranazayed6304]

Thanks for the video, where can i find the guide ?

[@learnelectrics4402]

Amazon is a good price for the on site guide. make sure it is the latest version, amendment two, brown cover.

[@radhialiue1974]

Thanks

[@learnelectrics4402]

You're very welcome. Thanks for watching. Dave.

[@danielteyehuago1633]

Please what of the cable calculation for single and three phase motors

[@learnelectrics4402]

Take a look at this video. If you know the load, you can calculate the amps and cable size.
czcams.com/video/bXiE9bdFLsU/video.html

[@MrBeats44]

How do I make a donation

[@learnelectrics4402]

The best donation is to tell others about the LearnElectrics channel. Spread the word. Thanks, Dave.

[@danielteyehuago1633]

I'm here again

[@learnelectrics4402]

You're very welcome.

[@ryanelliott6534]

hi mark niels

[@harveylennox1128]

hi ryan

[@ryanelliott6534]

@@harveylennox1128 hey babe

[@learnelectrics4402]

Thanks for watching.

[@learnelectrics4402]

Thank you for watching.

[@learnelectrics4402]

Thank you.