How to Calculate the Length of a Conductor Using Resistivity

Thanks mr.❤❤❤

That is really helpful video, educational and fun 😊 thank you so much guys

Hi Joe, another brilliant video, easy to understand and very interesting. One point, our College Lecturer and our course book says the resistivity of Copper is 17.5 x10-9. Does the difference matter? Thank you, you're a God send. Take care. 🤔❤

What happens if you are told you have a twin copper cable. Does that simply double the resistance?

So please apart from the meggar what instrument can be used to measure the resistance of a cable

Great video information 👍❤ THANK YOU FOR SHARING YOUR KNOWLEDGE AND EXPERIENCE 🇵🇭🫡❤

Guys don't suppose you know the resistivity of 4mm and 6mm solar PV cable please

what is the AWG of 1.5mm sq?

Great info bro. How can you measure the length of wire in different temperatures. What would be the math. Thanks in advance.

In the real world No one is going to mess around with this kind of maths when the a much simpler way of doing it. Unless you’re a 70year old boffin 😂

Clever bit of maths , but it’s to hard, the simplest way 0.19 ohms x1000= 190 milli ohms, 190 divided by 12.10 the factor from guidance notes 3 = 15.7 metres .
Great video and useful for the number crunchers👍

Very cool, but is measuring by hand still the most effective way?

The units are ohm M that's for extra mark ❤️

I’m not tripping right now did he say that the resistivity of copper is 17.2x10to the minus nine?!. Wasn’t it 1.72x10to the minus 8?! Am I stupid or something to not notice something obvious

massive help thankyou but according to my book the resistivity value of copper is 17.5 which gave me 16.2m which was a bit closer.

Hi Joe, need some help,
How do I figure out the length of wire when you have no resistivity. In the question I have to answer, Im give the CSA, COPPER RESISTIVITY and a voltage drop
please need some help understanding

OK Joe there has been a sun spot magnetic flare and every IC in the world has been fried . Now do the sum with out a calculator in long hand explaining every step?

Careful, I could lose count here. Brilliant, just brilliant. You can watch these vids more than once and still catch some funny bits that were missed on the first watch... Whilst learning at the same time,, You can't get better than that

Row ??

Hello sir i see your vd and you are a top master of science recently I had to find the length of cable we use for copper
R= 0,0175ohm/m and 2,5mm2 for cable when I use this formula it's not fit. The cable length measured 215cm and Resistance measured 0,37ohm can you please help to find the correct length thanks

Best regards. Could you help me to calculate the distance of a copper cable awg 10 using a multimeter Example I have a cable on a reel and the values shown by the multimeter in position 2k is .002 and in position 200ohms varies between 1.1 and 1.2 and continuity is .003. What would be the mathematical formula I should use to know the length of the cable. My knowledge in this area is not good, I am an apprentice.

Would it not be easier to express the value of p in microhms per meter rather then millimetres. that way its just (0.19*1.5)/0.0172 and you only have to do 17.2/1000. no need for a scientific calculator and you don't have to remember which values you have to x10^-6 or -9

A star delta is used in a 3 phase motor.The conductor from the star motor are wired 4mm2 copper conductors and have a resistance of 87.5mΩ.
Using the resistivity of the cooper conductor to calculate the length of one of the live conductor of the starter motor.
please help

Hiya Joe, how could you modify this formula to carry out an R1+R2 calculation. So rather than a single csa measurement on 1 conductor? calculation it is say a 2.5mm/1.5mm t&e👍

I tried to use your formula to calculate length. (To find the total cable routine underground and cable fault)

The problem is, when I calculate it out, the length is a huge difference from what is shown on my Autocad data i had on hand. Which i don't get how i got it wrong.

The cable is 3C x 185mm2.
The total resistance (I connect the end-point at B to form a loop back to A, together [in essence, 2xL]) is 0.2 Ohm
The length I calculated out is 1084m. However, the length on my Autocad data is sitting at a whopping 440m, which i can't figure out why

Hey Joe, I have to say you have helped me with really understanding resistivity as trying to learn it through Microsoft teams with over 30 other students has been hard on the students but especially the teachers, so you have been a massive help - as has rapid Gaz 🙌👏👏
I do have a question though... I have a question that says - you have an immersion that has a current of 13A. Its wired by a twin cable with each Conductor csa of 2.5mm^2. The Conductors are copper and the resistivity is 1.72x10-8 ohm/m^3 and I need to calculate the maximum length of cable which may be used, if the cable voltage drop is not to exceed 11.5V. (this is not the volt drop used for cable selection). How do I solve this? I presume ohm's law for the resistance, then the resistivity formula. But I am not sure if I should half the answer as its a twin cable?

Excellent, I remembered this from years ago!! Thanks for the refresher :-)

Hi, I understand the video and the workings.. However, I'm currently stuck on a question that has me stumped a bit. The question is this : Approximately how long would a length of CPC be to give a reading of 0.36 ohms, considering that 1.5mm(2) has a resistance per metre of 12.1 Milli ohms?
I don't know if/where the 12.1 should be substituted into the equation? Any help you can shed on to the subject would be amazing!!!

Just can't seem to get this working ... I have 30' of CCS #18 insulated wire. The closest calculation I can get is 127'. Using a multi-meter I get 0.5 Ohms resistance. The diameter of the wire is 0.05 inches or 1.27mm. Convert this to 1.27x10-6 m^2. I'm using 1.64x10-9 for the Resistivity of CCS. Help?

Can you help me out with this one. I'm still relatively newly qualified and trying to get my head around things. If you install a ring circuit of the max 100m then based on the table in the onsite guide, the resistivity of a 100m of 2.5 would be 100m x 19.51mΩ ÷ 1000 = 1.95 Ω. My questions are.....
1. How does that work if the max allowed impedance is 1.1Ω for 100m
2. If the answer is because impedence and resistivity are different things then is there a way to calculate the length of a cable from just the ZS. Thanks.

Great video joe. Could you have used the r1 r2 table in the on site guide and obtained a value of 12.10 milliohms per meter for a 1.5mm2 copper conductor..
Then calculate the length of the conductor = measured resistance x 1000 then divide that by(m ohms/m)??

0.19x1000 divide by
12.10
=15.70 meters???

Or am I missing something from the way I obtained my calculated value of length?

I love it, you had Gaz from GSH Electrical in your video Joe. ⭐️⭐️⭐️⭐️⭐️

Great stuff Joe, and all for free!!! 👍

Funny guys! Good info.

Awesome video Joe ...i was shown this onsite as an apprentice and was blown away how useful it was when fault finding on a ring final circuit 😎😎

I learned in college another way by using
measured zs ÷ r1 +r2 value × 1000 to convert to meters

Good vid

Wow you have GSH Electrical in a Joe Robinson Training video 👍. Great work lads you are changing Electrical training one video at a time 😀

Wow Gaz from GSH Electrical 👍😀👏

Is there any way you can do this calculation WITHOUT a scientific calculator ???I was trying 0.19 x 1000 / 12.10 = 15.7m   length0.19 Resistance12.10 resistance copper per meter OSG (table 11 /page 190)is this correct

Joe, are you going to do any videos on transposing formulae?

Yet again, super stuff!👍

😂😂😂😂

Got through it but typical city and guilds, exam related to next to nothing in their own worksheets? WHAT’S THAT ALL ABOUT C&G?

Perfect timing. I have my science exam at 19.30 tonight!
YOU SUPERSTARS!

Brilliant video. Keep the maths simple

👍👍

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