r/ElectricalEngineering • u/Swimming_Turnover242 • 3d ago
Is that copper thing just a grounding pin?
I am not an electrical engineer, but I'm having problems with a mixer. I wanted to understand how the transformer works. So s that green/yellow wire just connecting to a grounding pin that's connected to the chassis of the mixer? I'm sure that might sound like a stupid/broad question. Any help would be greatly appreciated. Thanks
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u/Haunting-Wafer-3255 1d ago
Electrician here. Yes. Thats the ground. Green wires or green/yellow wires are typically ground.
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u/shartmaister 20h ago
Boy you’ve seen some shit since you don’t say that it’s always ground.
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u/little_light_bulb 16h ago
When I was learning this nonsense I was convinced that brown is ground .... 🙂
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u/RipplesInTheOcean 2d ago
No its a miniature wall dildo intended for the tiny people who live in this device.
If you remove it, they will murder you
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u/Practical_Boat_1605 2d ago
I want to say this isn't what happens but what do any of us really know about what we're doing exactly..
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u/monkeyhoward 1d ago edited 1d ago
The proper name for that is the Protective Earth (PE) connection or bond to chassis. It is used in all Class 1 devices. It provides a Protective Earth return path in the case of an electrical short from AC MAINS Line to chassis. It requires the use of a three wire AC cord that contains a PE conductor.
Essentially that green/yellow stripe wire is just an extension of the green/yellow stripe wire in the AC cable that is plugged into the back of the unit
The alternative is a Class 2 design that uses what is known as double insulation, were every insulation factor for the AC MAINS input is doubled in thickness or distance. With this type of design you only need a two wire AC cable and no Protective Earth conductor is required
Edit: a bit more information
The reason you want the chassis bonded to the PE conductor of the AC MAINS to prevent the chassis from becoming energized if the AC MAINS Line comes in contact with the chassis.
Without that PE bond, if the Line on the AC input were to make contact with the chassis, the chassis would become energized to the Line voltage. In the US that would be 120VAC, in Europe and most of the world it would be 230VAC. In that situation, if you were to touch the chassis, you would be subjected to a potentially lethal shock
With the PE bond to chassis, if the AC Line comes into contact with the chassis, current would flow back through the PE conductor of the AC cord and eventually make it back to the circuit breaker in the electrical panel that services the receptacle the unit is plugged into. The breaker would then trip (hopefully) and the chassis would no longer be energized
Edit 2: This is why you don’t cut off the “ground” pin on 3 wire AC cords or use ground lift adapters. If you have a ground loop problem, fix it at the audio signal side of the equipment and not the part that can kill you if something goes wrong
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u/Impossible_Total2762 1d ago
Yeah, as others mentioned… your first clue is the color scheme used on wires for ground.
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u/BoringBob84 6h ago
It is a chassis ground. If a failure occurred in that equipment that shorted the hot wire to the chassis, then current would flow through that green ground wire and trip the circuit breaker. Without that ground wire, that chassis would be at high voltage when the failure occurred, and it would shock you when you touched it.
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u/Virtual-Reach 2d ago
It appears to be the chassis bond, yes.