18/2 wire

[dSilanskas]

Question that I was asked to ask here by my boss. He want to know if anyone knows how many amps can a 18/2 hold at 12 volts max?

[Jljohnson]

It really wouldn't have anything to do with the voltage, as long as your insulation is rated for the applied voltage. 310.16 list the amperage of a 90 degree rated 18 AWG conductor at 14. This could vary, depending on EXACTLY what type of 18/2 we are talking about....Thermostat wire, SO cord, Belden style cable????

[walkerj]

5.6 amps
240.4 D(1)

[Jljohnson]

5.6 amps
240.4 D(1)

Good call, forgot about that section. It seems that I have burned into memory the 15 amp for 14 and 20 amp for 12 part and forgot about the rest. :)

[dSilanskas]

T stat wire

[dSilanskas]

Thank you guys for your fast answers

[charlie b]

He want to know if anyone knows how many amps can a 18/2 hold at 12 volts max?
Depends on how long you want it to hold that current. I would bet that it could sustain at least 20 amps for several hours, if not days, if not even indefinitely, without melting the insulation. Or were you asking about code restrictions? :wink:

[Dennis Alwon]

5.6 amps
240.4 D(1)
Actually it is 7 amps max OCP unless it is a continuous load then it would be 5.6amps OCP and the other conditions apply.

[LarryFine]

I would bet that it could sustain at least 20 amps for several hours, if not days, if not even indefinitely, without melting the insulation.I bet that 20a would melt the insulation.

What would you like to bet? :D

[roger]

I bet that 20a would melt the insulation.

What would you like to bet? :D

Name the bet.

I guarantee I can load it to 20 amps for many hours without damaging the insulation.

Roger

[don_resqcapt19]

Name the bet.

I guarantee I can load it to 20 amps for many hours without damaging the insulation.

Roger
I'm not so sure about that. My calculations show that a #18 copper with 20 amps of current flowing will reach the commonly accepted maximum short time temperature of 150°C in ~18.5 seconds. This is based on the formula that says a copper conductor will reach 150°C when you apply 1 amp for each 42.25 circular mils of the conductor area for 5 seconds. This value is 38.34 amps for the #18 (1620/42.25). You use this value to obtain the ampere squared second rating used to calculate the time to reach 150°C for other current levels. The ampere squared second value would be 38.34 * 38.34 * 5 = 7248.78. If we divide this value by 400 (20 amps squared) we get a time of 18.37 seconds for 20 amps to bring the #18 to 150°C.
(note I have never seen this formula used for longer times, it is normally used for short circuit withstand current calculations and usually for times of 30 cycles or less, I am not sure if it really works for longer times)

[ELA]

Sounds like a simple experiment is in order?
In free air?

Gar?

[roger]

Sounds like a simple experiment is in order?
In free air?

Gar?

I would be force cooling it as in submerged in flowing cold water.:wink:

Roger

[Rockyd]

Kind of like the cooling of a A Superconductor? (http://www.youtube.com/watch?v=jQ7YdijQ5q8)


http://homepage.mac.com/cheilman1/images/photos/101/superconductor.jpg

Superconductor! (http://images.google.com/imgres?imgurl=http://www.stevespanglerscience.com/img/cache/bcb9b8db117ee64376aedaf7af3595ca/superconductor-8607-260x250-260x250.jpg-8607-340x340.jpg&imgrefurl=http://www.stevespanglerscience.com/experiment/superconductors-the-floating-magnet&usg=__b-FaGjeTF2nRiiPSZJ467hLJX3A=&h=340&w=340&sz=12&hl=en&start=2&um=1&tbnid=UaX0gQcuEUiyQM:&tbnh=119&tbnw=119&prev=/images%3Fq%3DSuperconductor%26um%3D1%26hl%3Den%26s a%3DN)

[LarryFine]

Name the bet.

I would be force cooling it as in submerged in flowing cold water.:wink:
The bet's off then! 8-) Bah! Water cooled! Harumph! As if!