Wire Gauge - AWG, Amperage, Diameter Size, & Resistance Per Unit Length

This electronics video tutorial focuses on the american wire gauge - AWG. It discusses the relationship between wire size, amperage, diameter in mm, and resistance per unit length in milli-ohms per ft. This video also explains how to calculate the maximum voltage that can safely be applied to a wire of a given length and size.

Basic Electronics For Beginners:

Electric Power & Cost if Electricity - KWh:

Electricity - Basic Introduction:

Intro to Multimeters:

The Wheatstone Bridge Circuit:

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Node Voltage Method Circuit Analysis:

Mesh Current Circuit Analysis:

Norton's Theorem Circuit Analysis:

Thevenin's Theorem Circuit Analysis:

The Superposition Theorem:

Maximum Power Transfer:

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[thomasdilbert]

You just demystified wire science for me - been trying to find an understandable explanation for years - many thanks, Dr. D.

[ademolaalade]

Very excellent, simple and straightforward on the subject topic. Kudos

[alindamanda]

R= ρL/A, where ρ is the resistivity of material ( a constant), L is the length of material and A is the area of the material. So if we use a standard wire most of the time is round so A = πr², where r is the radius of the circle ( the cross-section of the cable). So if r increase ( larger cable diameter) then A increase then R decrease. Resistance is directly proportional with length but inverse proportional with diameter.

[joehead]

Wire is rated for max voltage on the insulation, along with temperature rating and conductor size and insulation material. Max amperage of a conductor has to do with the environment it's installed in and the temperature rating of the insulation. Voltage drop also has to be considered.

[sureshlingabathina]

Best ever tutorial ever watched on subject on YouTube.

[jamesmcd]

Thank you so much. I'm installing a Backup generator to run my house and I have been having the hardest time doing the math on the cable from the Generator to the house. I'm putting it 126 feet from my ATS and I couldn't find a chart with length over 50ft.
Again thanks.

[larrybland]

Omg, this video solidified my decision to become an engineer. I work for a telco and the techs deny any logical concept “ANY LOGICAL CONCEPT!” For example a technician told me that a wire that was 10AWG and roughly 10ft long could safely conduct 14, 000v without melting to a puddle

[TheHighwayGroupie]

Very good up until your misapplication of V=IR. If you use that formula the way you present it, then a wire of only 10 feet would only handle 0.375 volts at 15A, or 5.625 Watts. That answer is ridiculous and would mean that all kitchen appliances around the world should be burning up their wires. The formula is Wire Length = ( VD x 1000) / (LC x 2 x R), where VD = I xR x V. Also, I believe you wanted to say 20C, not 60C. The resistance measures are based on 20C or 68F. Hope this helps.

[aws]

The V = IR yiu calculated is Voltage Droop along the wire due to current. It means if the wire resistance is 22.5 Ohm and current is 15A, the different between the power source and load is 337.5V. It is a simple calculation at power factor of 1.

[om_WHAT]

감사합니다.AWG 규격이 무슨 원리로 만들어져 있는가가 항상 궁금했었는데..설명이 아주 명쾌합니다. 고맙습니다^^

[MathWebs]

This discussion is needed, a bit refreshing for a sermingly difficult topic. In a recent video, I show a new, somewhat simpler, formula for wire diameter.

[badchips]

A useful addition to this video would be a short discussion on voltage drop based on length of cable and size. It is more useful than knowing how to calculate maximum voltage for certain length and size. That can be useful if you operate tools with motors.

[davidjackson]

Glad to see American speaking sense with "metric." But gives me an idea, wire size gauge should be redone so instead of size it gives resistance per meter would save a lot of mucking around. etc...

[joshuacook]

What an amazing video. well detailed, and describe. thanks for the better understanding of AWG, resistance, amperage .

[successthruknowledge]

Recently I graduated from Phlebotomy course where GAUGES for needles were numbered in a similar fashion, . The Gauge Number is due to the manufacturing process. Needles and wires are created by passing metal through dies with holes of smaller and smaller diameter. So the first 'pass' through a die with a certain size hole creates a wire or needle of a certain diameter say for example 1 so PASSAGE 1 is GAUGE 1. Then that same wire could be dragged through another die with a smaller diameter hole to create an even narrower wire or needle and then would be PASS/PASSAGE 2 so GAUGE 2. So the narrower the die hole then the narrower the wire so it would be done at later and later PASSES/PASSAGES which would be a greater number thus a greater gauge number.

[rockefelleragent]

Thank you for the free online course on electrical wires..

[acmefixer]

Thanks for the explanations. The maximum voltage applied to the wire is determined by the insulation rating. The question should have asked what is the maximum voltage drop across 9000 feet of 14AWG wire. The question would never have a real world application because 15 amps times 337 volts would be wasting over 5000 watts of power in the wire and almost none of the power would get to the load at the far end. Thanks again.

[enriquepena]

Do you have a video about lenght and voltage drop? Thanks

[pattayaguideorg]

Man... that was so helpful, thank you.

[richd]

Thank you for your time and the work which can b a blessing for us trying to keep vintage Dodge 6 volt and other American carb motors.
A tutorial on resistance and your cool explanation and teaching is appreciated. Los Angeles has no teaching or shop teaching, seems the sitdown keyboard industry has no hands on curriculum.