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Transferring Power
dflee:
Was playing around with my power cord progression and have a question.
Can a power cord, if under sized gauge wise, cause a piece of equipment to
brown out or fail due to not enough juice? Can it damage the equipment over time?
Don
S Clark:
In theory, in some weird circumstance, yes. In the real world, I'd think the issue would be the power cord overheating, and then only for something drawing high amperage- some kinda monster power amp.
Folsom:
Yes but unless you have a straight up short then it would probably need to be smaller than anything anyone would use. A 30awg PC probably wouldn't fail if the turn on surge didn't pop it because even at 5ft it'd only be 1ohm. For classA it probably would fail. That doesn't mean that larger won't sound different, but actual power loss takes significant current through something small. The heat happens from current, and voltage will sink as the resistance drops it. The more heat the higher the resistance.
tmazz:
--- Quote from: dflee on November 16, 2019, 08:09:05 AM ---Was playing around with my power cord progression and have a question.
Can a power cord, if under sized gauge wise, cause a piece of equipment to
brown out or fail due to not enough juice? Can it damage the equipment over time?
Don
--- End quote ---
By brown out I assume you mean an under voltage condition at your amps AC input. Let's look at the just mentioned example of a 30AWG wire, which is way smaller than any of us would ever consider for a power cord. As was mentioned 5 ft of 30 ga measures 1 ohm. If you feed that with a standard 15A circuit the max voltage drop you will get across that PC would be 1 ohm times 15 amps or a 15 volt drop. Just to give you an idea of how thin 30 ga wire is it is, if you have ever wired a telephone jack in your house, 30 ga wire is 1/2 the diameter of that. And by the way, the max current rating for a 30 ga copper wire is on 1/2 amp, so it would fuse long before it reached 15 amps.
But that aside if you look at even 16ga wire, which is the smallest size wire that is rated safe for use in a 15 amp plug, the resistance of a 5 ft PC would only be 0.04 ohms. So at the max amperage that the plug could provide you would only drop 6/10ths of a volt across the power cord.
So the bottom line here is as long as you have wire gauges in the power cord that meet or exceed the National Electric standard for the max load they could carry (which anything sold commercially would have to do) you will have no chance of dropping enough voltage across the cord to cause a problem for your equipment.
And most of us who use after factory power cords have ones that far exceed the NEC minimums. My the copper in my TWL cords are rated by NEC standards for over 40 amps and I have them plugged into 20 amp circuits.
Guy 13:
--- Quote from: tmazz on November 16, 2019, 06:15:22 PM ---
--- Quote from: dflee on November 16, 2019, 08:09:05 AM ---Was playing around with my power cord progression and have a question.
Can a power cord, if under sized gauge wise, cause a piece of equipment to
brown out or fail due to not enough juice? Can it damage the equipment over time?
Don
--- End quote ---
By brown out I assume you mean an under voltage condition at your amps AC input. Let's look at the just mentioned example of a 30AWG wire, which is way smaller than any of us would ever consider for a power cord. As was mentioned 5 ft of 30 ga measures 1 ohm. If you feed that with a standard 15A circuit the max voltage drop you will get across that PC would be 1 ohm times 15 amps or a 15 volt drop. Just to give you an idea of how thin 30 ga wire is it is, if you have ever wired a telephone jack in your house, 30 ga wire is 1/2 the diameter of that. And by the way, the max current rating for a 30 ga copper wire is on 1/2 amp, so it would fuse long before it reached 15 amps.
But that aside if you look at even 16ga wire, which is the smallest size wire that is rated safe for use in a 15 amp plug, the resistance of a 5 ft PC would only be 0.04 ohms. So at the max amperage that the plug could provide you would only drop 6/10ths of a volt across the power cord.
So the bottom line here is as long as you have wire gauges in the power cord that meet or exceed the National Electric standard for the max load they could carry (which anything sold commercially would have to do) you will have no chance of dropping enough voltage across the cord to cause a problem for your equipment.
And most of us who use after factory power cords have ones that far exceed the NEC minimums. My the copper in my TWL cords are rated by NEC standards for over 40 amps and I have them plugged into 20 amp circuits.
--- End quote ---
tmazz :thumb:
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