Saw this video. Wondering about how accurate it is - 14 gauge wiring at high amperages.

Irving

Joined Jan 30, 2016
3,132
Oh yes its accurate. I use 12AWG @ 40A for battery charging and they get to around 80degC but then they are silicon insulation rated at 200degC. Normal PVC melts at 90degC. Its worse in conduits where cables are tightly packed. 14AWG has to be derated to 25A in conduits, 35A in free air.
 

Reloadron

Joined Jan 15, 2015
6,979
I see it as accurate. Did similar test on wire where we used small thermocouples to measure temperature rise on wire. Irving in the above really nailed it well pointing out what happens in conduit verse free air.

Ron
 

ThePanMan

Joined Mar 13, 2020
496
This is a surprise to me. I wouldn't have expected 14 gauge to handle more than 30 amps. Cool video. As for accuracy? I don't see why it could be fake or some factor someone failed to take into account.
 

Irving

Joined Jan 30, 2016
3,132
This is a surprise to me. I wouldn't have expected 14 gauge to handle more than 30 amps. Cool video. As for accuracy? I don't see why it could be fake or some factor someone failed to take into account.
Depends on your definition of 'handle'. The fusing current of 14awg is 166 amps, but you can only use it at currents that don't damage the insulation. The title is 'How much current before it burns', not the wire melts or fuses. To some extent that depends on the rating of the insulation. Normal domestic/residential is 75 or 80C. Industrial is 90C. Specialist can be 200C or higher..
 

shortbus

Joined Sep 30, 2009
9,643
I must be missing something? Why is his welder only putting out such a low voltage? Most arc welders output is in 35-40 Volt area.
 
I was once putting a lot more than 30 amps through a 14 gauge extension cord running across the floor. At some point I stepped on it and it just exploded. My theory was that it was barely managing to stay in thermal equilibrium and, when I stepped on it, I blocked the loss of heat to the environment somehow and it got real hot real fast,
 
I must be missing something? Why is his welder only putting out such a low voltage? Most arc welders output is in 35-40 Volt area.
Depends on the welder. Some welders, like stick and TIG, are current sources so the voltage will be low when the resistance of the circuit is low. MIG welders are voltage sources. They rely on the wire burning back to raise the resistance of the arc to the equilibrium point.
 

Reloadron

Joined Jan 15, 2015
6,979
I must be missing something? Why is his welder only putting out such a low voltage? Most arc welders output is in 35-40 Volt area.
My best guess is because the welder is driving what amounts to a close to dead short. The guy has maybe 2 to 3 feet of AWG 14 round trip so pretty close to a short. I was not a welder you have likely welded more in a 6 month period than I have in my life. I did work with quite a few welding machines and procedures for their verification. Open circuit voltages were as high as 90 volts on some. Actual arc voltages around 12 or 13 volts and some were adjusted by moving the weld head up or down from the workpiece. That on machines where the arc control voltage was preprogrammed. Anyway in this case the welding machine is working into close to a dead short. What I did not quite get was at 15 Amps the voltage was 0.350 volts and at 30 Amps 0.7 volts which makes sense but I had a hard time seeing the decimal point on his voltmeter. Then at higher currents as the current increased the wire got hotter and as expected the resistance started to increase and the voltage drop followed which is what I would expect. Anyway the welder supply was working into 6 feet about of AWG 14 so maybe 0.015 Ohm load. Thats my best guess. :) There was no arc.

Ron
 

k1ng 1337

Joined Sep 11, 2020
687
I was once putting a lot more than 30 amps through a 14 gauge extension cord running across the floor. At some point I stepped on it and it just exploded. My theory was that it was barely managing to stay in thermal equilibrium and, when I stepped on it, I blocked the loss of heat to the environment somehow and it got real hot real fast,
oops.jpg
 

MisterBill2

Joined Jan 23, 2018
13,141
Probably the explosion was caused by the quitr hot wires touching when you stepped on the cable. Insulation will deteriorate at those high temperatures. Some kinds of insulation will actually melt and flow. Then the smallest touch and a shorted circuit results and with enough power you can get an explosion and a blast of ARC FLASH that leaves a copper stained burn. AND, by the way, it is painful.
 

MrSalts

Joined Apr 2, 2020
2,376
I must be missing something? Why is his welder only putting out such a low voltage? Most arc welders output is in 35-40 Volt area.
He is controlling current through a very good conductor (copper). Ohms law determines the voltage drop across the 4-feet of 14-gauge wire. At 0.0025 ohms per foot, and 40 amps applied, he should get, as measured, 1 volt.

The voltages are typically limited to a max voltage in the range of 30 to 45 volts to keep them safe and they will default to that voltage when not connected to compete the circuit. While welding, the voltage will fall based on the resistance of the material the electrodes are connected to.
 

Ya’akov

Joined Jan 27, 2019
6,575
I was once putting a lot more than 30 amps through a 14 gauge extension cord running across the floor. At some point I stepped on it and it just exploded. My theory was that it was barely managing to stay in thermal equilibrium and, when I stepped on it, I blocked the loss of heat to the environment somehow and it got real hot real fast,
Or the insulation had melted enough the you shorted it.
 

MisterBill2

Joined Jan 23, 2018
13,141
The basis for the electrical code current ratings for wires are temperature rise and voltage drop.
I did not watch the video, but I am wondering if there was a voltage reading across the ends of that wire in the test. That would have been useful and very educational.
 

Reloadron

Joined Jan 15, 2015
6,979
The basis for the electrical code current ratings for wires are temperature rise and voltage drop.
I did not watch the video, but I am wondering if there was a voltage reading across the ends of that wire in the test. That would have been useful and very educational.
Yeah, he measured voltage and current. At 15 amps wire cold he got 0.350 volts and at 30 amps he got about 0.700 volts which sounds about right. He did not measure or define wire length. You really have to watch the video to get the whole picture of what was going on. As the wire got hot you could see the voltage drop changing for an applied current as the wire resistance increased. Anyway it was all about what I would have expected to see. Also the wire used looked to be AWG 14 for example ROMEX about maybe 3 feet long. He shorted two conductors at one end and applied his current from the opposite end. Just watch the video.

Ron
 

Thread Starter

Tonyr1084

Joined Sep 24, 2015
7,098
I would have never expected 14 gauge to conduct so much current. But then again I'm also wondering how (or why) stereo speakers can handle such high wattages through 18 gauge wires. My thinking has always been that the heavier gauge wires would conduct more musical energy than thinner wire. And that's likely true, but I just didn't expect so much amperage through the 14 gauge wire before insulation started to emit smoke. I did notice the blackening of the outer sheathing at lower currents, so I would consider that to be unsafe. To say the least, code says 14 gauge wiring in the house should be protected by a breaker no larger than 15 amps. And I continue to live by that principal. Basically for two reasons - 1) don't want a fire. 2) if there IS a fire insurance may determine it was due to improper wiring that did not meet code. In case #2 insurance would not pay and I'd be on the hook for all the repairs. And if someone were to be hurt by said fire I could be held liable if it were something I installed.

My home is mostly 12 gauge and 20 amp breakers. Two circuits run 30 amps and one runs 50 amps. All with the proper wiring thankfully. But the reason why I asked if it was accurate was because YouTube video's are sometimes faked. We've all seen that. Especially if you've ever watched a "free energy" video. And no - moderators - this is not about free energy. That's a taboo subject here and will not be pursued.
 

MrSalts

Joined Apr 2, 2020
2,376
The fusing currentof 14-gauge wire is 166A (10 seconds) and 633 A at 1-second. Little differences can cause fusing at lower currents. Note that the insulation started to burn first at the sharpest kink.

 
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