How much current does AWG 24 wire carry?

[eeguy]

Hello, different sources provide different answers. One stated 0.577A. The other 7A, etc. Which is correct?

[jpanhalt]

Current rating reflects allowed temperature rise and is affected by insulation and packing.  In free air for bare wires, this table indicates about 800 mA to 900 mA:   https://www.pupman.com/listarchives/1998/April/msg00222.html

Edit: Fixed link

[ejeffrey]

Both, or neither. It depends on how it's used.

Here is one table: https://www.powerstream.com/Wire_Size.htm

It lists the limit as 3.5 amps for "chassis wiring" which is a single insulated wire in air, 0.577 amps for "power transmission" which is a bundle of wires.   Bare wire can conduct more, and different insulation has different temperature limits.  Short wires where a lot of heat is dissipated through the ends can condict more.  Wires in a potted enclosure can carry much less.

[IanB]

In addition to thermal limits, you may in some cases be concerned about the voltage drop in the wire, especially over long runs.

[CatalinaWOW]

In addition to the factors which jpanhalt mentions, which affect how hot the wire gets, different safety standards can affect this.

One source may be quoting the current at which the wire melts (which is also affected by the specific alloy), another may restrict the temperature to the softening temperature of the insulation, and yet another may keep the temperature below what is safe to touch.

If you don't have the tools to evaluate all of the factors involved I would restrict current to the low end of the recommended ranges.  Wire is cheap.  Burns and fires are not.

[eeguy]

Thanks.

I saw a stepper motor has a rated current of 2.1A. The four wires coming out of the motor are non-removable. I asked the manufacturer the AWG value and they said 24. Does each of those four wires considered to be a "bundle of wires" which means they are limiting the full potential of the motor as only 0.577 amp will be supplied to the motor?

I got a Meanwell LRS-250-24 power supply. Now I am choosing:

- power cord (AWG18 vs 14)
- wires between the IEC320 C14 Inlet Module with switch and the power supply
- wires from the power supply to motor controller.

For these power cord and wires, is it better to use AWG 18, 16 or 14?

[Siwastaja]

You have seriously misunderstood something. Wire thickness has nothing to do with the current it will carry. In a stepper motor specifically, it will carry the current your stepper motor driver is configured to use. You can pass 1000000000A through that wire. The only question is if the wire gets too hot while doing that, to the point of the insulation melting or catching fire. Normally you would believe the manufacturer has done their engineering properly and the specifications can be trusted without asking questions about such design details, but of course some amount of derating is usually helpful for maintaining long life.

[eeguy]

You have seriously misunderstood something. Wire thickness has nothing to do with the current it will carry. In a stepper motor specifically, it will carry the current your stepper motor driver is configured to use.

In the past, a senior at school told me that the thicker the wire, the more the current it could pass through. That is where I got that idea.

[Coordonnée_chromatique]

https://www.engineeringtoolbox.com/wire-gauges-d_419.html

[Siwastaja]

You have seriously misunderstood something. Wire thickness has nothing to do with the current it will carry. In a stepper motor specifically, it will carry the current your stepper motor driver is configured to use.

In the past, a senior at school told me that the thicker the wire, the more the current it could pass through. That is where I got that idea.

Yeah. This underlines how important it is to be exact and include as much information as possible. What they failed to tell you, or you misunderstood, was this important piece: "without damage".

Usually, ignoring going to extremes, the wire would not actually control or limit the current. The current would be defined by the rest of the circuitry - in your example, by the stepper motor controller - ; then the job of the wire is to be thick enough to survive the current without smoke, and also thick enough to minimize unwanted losses. If the wire is short, then it's usually more about survival than losses, but for long wires losses start to matter even if heating is modest.

[pcprogrammer]

You have seriously misunderstood something. Wire thickness has nothing to do with the current it will carry. In a stepper motor specifically, it will carry the current your stepper motor driver is configured to use.

In the past, a senior at school told me that the thicker the wire, the more the current it could pass through. That is where I got that idea.

In principle this is correct, but:

Current flowing through a wire is basically based on two things, the voltage and the resistance. A thicker wire has less resistance than a thinner one, but length also plays a role. A short wire has less resistance than a long wire of the same thickness. The material the wire is made from also plays a role.

So it depends on all these properties what the resistance of a wire is and that will determine how much power is going to be dissipated in the wire. P = I^2 * R. Throw time in the mix and this will lead to a temperature rise of the wire.

Your stepper motor has windings that are rated for 2.1A, so this current will also flow through these four 24 AWG wires, but they are short and won't have much resistance. So the power dissipated in the wires won't be a lot.

It might well be that the rating you found is given per meter of wire.

[iMo]

..You can pass 1000000000A through that wire..

Can an AWG 24 wire conduct 1000000000 Ampers?

ChatGPT:

No, an AWG 24 wire cannot conduct 1 billion (1,000,000,000) amperes. The American Wire Gauge (AWG) system is used to standardize the diameter of round, solid, nonferrous, electrically conducting wire. A higher gauge number indicates a smaller wire diameter. AWG 24 wire has a diameter of about 0.51 mm (or 20.1 mils).

The current-carrying capacity, or ampacity, of a wire depends on various factors including the wire's material (usually copper or aluminum), insulation type, the ambient temperature, and how the wire is installed. However, the ampacity of an AWG 24 copper wire is typically around 3.5 amps for chassis wiring (short, exposed runs) and about 0.577 amps for power transmission, according to the National Electrical Code (NEC) and other guidelines, assuming a temperature of 20°C with no additional heat sources.

Conducting 1 billion amperes through a wire would require a wire of an enormously larger size and would also involve substantial infrastructure to manage the immense heat generated and magnetic forces produced. Such currents are far beyond the scope of practical electrical wiring and are not encountered in conventional electrical engineering or power distribution systems.

[IanB]

Can an AWG 24 wire conduct 1000000000 Amperes?

This is where ChatGPT falls short. The question is not "if", but "for how long?"

Certainly the wire will vaporize, but in order to vaporize, it had to be carrying that current for some minimum time like a nanosecond before that.

[eeguy]

Your stepper motor has windings that are rated for 2.1A, so this current will also flow through these four 24 AWG wires, but they are short and won't have much resistance. So the power dissipated in the wires won't be a lot.

It might well be that the rating you found is given per meter of wire.

 
The company told me that the wires from the motors are 500mm(UL1007 AWG24).
So, what wire gauge is recommend for the power cord (AWG18 vs 14),
wires between the IEC320 C14 Inlet Module with switch and the power supply as well as
the wires from the power supply to motor controller (one could output 4.2A and the
other 5.6A, not decided which to get yet)?

[baldurn]

Besides all that, the motor is not going to be drawing 2.4A continuously through one set of wires. I would expect the average to be half of that maximum.

[golden_labels]

Continuing with the jocular tone, I say it’s not “for how long” but “if”. With gigaamperes we may need to treat a wire as a transmission line just to account for it evaporating before it starts to fully conduct.

Quick, somebody ping Veritasium or AlphaPhoenix to answer the question. We need another epic YouTube creators argument!

[themadhippy]

just chuck it in the freezer until it reaches 0 kelvin an it should be good for few  billion amps

[golden_labels]

Slightly, but only slightly, more serious tone now.

Resistivity of metals is ρ ≈ 10^-8 Ω·m. With the cross-section area of about 10^-7 m², we get resistance of 10^-1 Ω/m. To get 10⁹ A current, the voltage across a meter of a wire would need to be 10⁹ · 10^-1 (A·Ω/m) = 10⁸ V/m.

So you will need a pretty good isolation materials and geometry to produce 1 GA.

[baldurn]

Continuing with the jocular tone, I say it’s not “for how long” but “if”. With gigaamperes we may need to treat a wire as a transmission line just to account for it evaporating before it starts to fully conduct.

The wire is just there to get the spark going. As soon as it arcs over, the wire is no longer needed.

[T3sl4co1l]

Can an AWG 24 wire conduct 1000000000 Amperes?

This is where ChatGPT falls short. The question is not "if", but "for how long?"

Certainly the wire will vaporize, but in order to vaporize, it had to be carrying that current for some minimum time like a nanosecond before that.

Actually, I would dispute that this is possible at all: consider the dI/dt required to reach such a current even in such time scale where the wire might possibly not immediately vaporize.  Likely the voltage drop is sufficient to break down in air at the very least, and most likely cause field emission in vacuum too.  The wire (and any insulation covering it) would quickly be consumed by the resulting plasma, and, I suppose, fully ionized in the process; the voltage drop might actually rise because no more free electrons are available.  Eventually pair production would occur, stabilizing the voltage drop; or nuclear reactions.

For reference, the Z-machine does ca. 26MA, triggering nuclear reactions.  The focus is, I think, a bit smaller than a 24AWG wire, but depending on length in question, perhaps it is comparable.

So, we can, with a little confidence, rule out currents quite this high, I think.

Continuing with the jocular tone, I say it’s not “for how long” but “if”. With gigaamperes we may need to treat a wire as a transmission line just to account for it evaporating before it starts to fully conduct.

Worse, not only would TLs be required to even begin to attempt such an experiment, nuclear physics gets involved, too.

...

As an exploding bridgewire, I think on the order of ~10kA and <1us, skin effect dominates, concentrating the power dissipation in the surface, and ~instant vaporization can occur; at lower dI/dt, probably this current is survivable, up to, oh I don't know, maybe 100s µs, 1 ms or so?  Beyond which, (bulk) melting and vaporization occur rapidly.

These are fairly -- well, not common, but plausible, let's say -- induced-lightning surge currents, within the realm of commercial or industrial practice.  Somewhere around here might be considered the ultimate limit for such wire.

...

Anyway, yeah.  For continuous or intermittent use, you can jam practically as much current as you want, until the wire heats up too much.  The real question is, how hot is acceptable?  How much voltage drop?  Wiring tables assume some condition (limiting temperature at worst-case power dissipation capacity, e.g. wires in conduit in insulated wall space), so tend to be highly conservative.  Chassis wiring is typically short and has good air circulation, so that more current can be passed for the same temp rise -- note that short wiring length, besides keeping the voltage drop down, also can provide some heat sinking out the ends of the wire, heat flow is not strictly radial (out of the wire surface) but lengthwise as well and therefore different assumptions apply.

Which is similarly relevant for PCB trace width calculations: it's practically irrelevant if the length is short or the aspect ratio isn't monstrous, and mostly matters on long narrow routes where heat flow is lateral.

Connectors add a whole 'nother wrinkle, as they might be rated more-or-less what the wire is, but the contact point(s), pressure, plating, temperature range, temp cycling, and mechanical vibration, all play a role in their endurance.  Failure typically occurs when contact resistance increases too far, and the pin burns up.  This can take merely hundreds of mechanical cycles (for poor quality or mismatched plating), and may be exacerbated by current flow (heating, electromigration).  High-current connectors typically have multiple contact points -- contacts designed with multiple leaf springs, usually with a bump projecting from the surface into the terminal/post to concentrate contact pressure, and this takes up both mechanical tolerances and helps ensure consistent contact under motion.  That said, I've seen ratings from 2 to 5A for headers in the style of Molex KK 0.1" series -- the upper range I believe by Sullins, though I don't recall their terminals looking any different from Molex's. 

Tim

[Jwillis]

Wire can carry a lot more than what is considered the acceptable standard. https://en.wikipedia.org/wiki/American_wire_gauge. The UL and CSA standards give a more detailed description of the current capability of transmission lines based on the number of bundles. The NEC will have their own standards based on the type and capability of the insulation.
How and at what current a wire fuses at depends not only on the gauge but also the type of conductor used. Aluminum wire will fuse at a lower current than cooper for example.
Theirs no rule that states that you can't pull more current through a wire than what is considered standard. It depends on what you would consider and acceptable voltage drop and temperature rise of the wire for your experiment. But your not going to instill much confidence in you project or product if it's smoking or on fire.

[mag_therm]

Theirs no rule that states that you can't pull more current through a wire than what is considered standard.

Yes there are such regulations based on C.S. Area, for installations covered by the Electrical Wiring standards in most countries.

But if you design equipment such as transformers, the standards are not based on conductor sizes.
However safety is then covered by insulation temperature rise standards.

[alligatorblues]

Iin the USA, RESIDENTIAL wiring is one gauge larger than standard ampacity in any other application, because most homes lack fire suppression, and electrical is the most common cause of house fires. Whithin the shroud of electric using appliances, the figure for house wiring halves, so if you can use use 14AWG for 15A in residential building, inside a manufactired device, it can be used to carry up to 30A. 

The smallest 120VAC wiring is 14 AWG, because it's the smallest that can withstand the tensile force of fishing in conduit. After 14AWG, 16, 18, 20, etc., the rules completely change. 28AWG is industrially rated for 800mA. However, a main concern is preserving insulation and preventing injury, property damage and/or equipment failure. As long as none of that happens, it's cool.

My uncle works in installation and maintenace of UPSs. In one data center, there was a room full of manual maintenance lead acid batteries, with a 20 year life. But they had to be checked for output voltage, and have water  added. One of the guys working on those batteries lost his balance. The room was 20 feet high. So, they needded planks. He hit those terminals just perfectly. He was instantly fried. Another guy was working on 480 3ph, and there's these things called tin whiskers, where tin-finished and tin soldered electical devices grow projections sometimes 10mm long. Once in a while a tin whisker will complete a short circuit, causing a cataclysm of vaporized metal flying in all directions. Usually they just melt away. But if another short is caused by the first one, a whole breaker panel can explode.

That happened to my uncle. A 480 3ph junction box just exploded, leaving not a trace. He had a visor on and a Nomex suit.

These ups's have so much power, ATT put 25 750kva units for one of their data centers. The load used to test it had to be carried on a semi trailer.     

Got off track. Silicone and Teflon, 2 very chemically inert and heat resistant insulations can raise ampacity 2-3x over Romex or pvc insulation. Ampacity is based on heat production and ability to withstand it. A wire is a resistance. The thinner the wire, the higher the resistance.

From V=IR, the lower the Ohms, the higher the current. 120V driving current through a resistace of 1.2 ohms will produce a current flow of 100A. 120/1.2=100. Soft, annealed, pure copper 24 AWG wire has resistance of 0.026 Ohms per foot.

If you're using a drive voltage of 24VDC through 5 feet of 24 AWG copper wire, R=0.13 Ohm. 24VDC/0.13 Ohm=184A for a short circuit. P=I^2R; 184^2=33856*0.13=4401 Watts. So, you get a little idea of how these three basics interact.

Joules are energy. This unit can be expressed  in many ways. But one is:  the work required to move 1 Coulomb of electric charge through one volt (C*V). The ampere is 1 Coulomb/second. Watts are power, or Joules/second. And Kilowatt-hours are Joules. 1 kW*hr=3.6 million joules. If you assign units  to your operands, you always know if the result is correct, because the answer is in the correct unit. 

So, you have to learn how to choose your wire. I use 18-22AWG silicone insulated hookup wire for almost everything. It's really nice to work with, and I don't use much, so cost isn't a factor.

[ejeffrey]

Thanks.

I saw a stepper motor has a rated current of 2.1A. The four wires coming out of the motor are non-removable. I asked the manufacturer the AWG value and they said 24. Does each of those four wires considered to be a "bundle of wires" which means they are limiting the full potential of the motor as only 0.577 amp will be supplied to the motor?

No this should be fine.  The wires are short, and while they may be 4 wires "bundled" that's not the same as a 2" diameter  conduit stuffed full of wires running for 100 feet.  2.1 amps is fine for this sort of thing, especially since only one pair of wires will be carrying the max current at any given time.

I got a Meanwell LRS-250-24 power supply. Now I am choosing:

- power cord (AWG18 vs 14)
- wires between the IEC320 C14 Inlet Module with switch and the power supply
- wires from the power supply to motor controller.

AWG 18 is fine for all of those purposes.

[eeguy]

Thanks.

I saw a stepper motor has a rated current of 2.1A. The four wires coming out of the motor are non-removable. I asked the manufacturer the AWG value and they said 24. Does each of those four wires considered to be a "bundle of wires" which means they are limiting the full potential of the motor as only 0.577 amp will be supplied to the motor?

No this should be fine.  The wires are short, and while they may be 4 wires "bundled" that's not the same as a 2" diameter  conduit stuffed full of wires running for 100 feet.  2.1 amps is fine for this sort of thing, especially since only one pair of wires will be carrying the max current at any given time.

I got a Meanwell LRS-250-24 power supply. Now I am choosing:

- power cord (AWG18 vs 14)
- wires between the IEC320 C14 Inlet Module with switch and the power supply
- wires from the power supply to motor controller.

AWG 18 is fine for all of those purposes.

Thank you. I proceed to order then.