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The switch will work either way. However, there are significant safety benefits to installing switches on the hot wire. For residential AC in the United States, only one wire actually has a potent...
Answer
#2: Post edited
by
matthewsnyder
·
2023-07-06T21:24:22Z (over 1 year ago)
- The switch will work either way. However, there are significant safety benefits to installing switches on the **hot** wire.
In residential AC, only one wire actually has a potential difference (the "hot" wire, usually red or black) while the other wire is neutral (usually gray or white). Note that "neutral" is not the same as "safe to touch" - what the *grid* considers neutral may be quite different from the ground, so you should not go touching neutral wires unprotected. But it is generally not expected that it has the same powerful voltage as the hot wire.- When current is passing through devices, it is quite visible. It is obvious that you shouldn't try to stick piece of wire into the housing of a lightbulb which is on. And indeed, when the switch is on, the entire circuit is dangerous.
- When the switch is off, there is no current, but the voltage still propagates through the parts of the circuit connected to the hot wire (and the grid). Those parts (before the switch) are very dangerous. The rest of the circuit (after the switch) is significantly less dangerous. If you put the switch on the neutral wire, then the dangerous part will include the device (eg. lightbulb). Unlike current, voltage is hard to see unaided, and with the switch open the lighbulb will appear to be off despite having a significant voltage. The moment someone touches the housing, the electrons will rush through that person to the ground, and electrocute them in the process. This is arguably a surprising result to most people, because they would not expect to be electrocuted when "the switch is off".
- For this reason, putting the switch on the hot wire improves safety in two ways:
- * Reduce accidents when people accidentally touch the contacts of an electrical device which is off
- * Doesn't mislead people into thinking a device is safe to work on "because the switch is off and the device seems unpowered"
- The switch will work either way. However, there are significant safety benefits to installing switches on the **hot** wire.
- For residential AC in the United States, only one wire actually has a potential difference (the "hot" wire, usually red or black) while the other wire is neutral (usually gray or white). Note that "neutral" is not the same as "safe to touch" - what the *grid* considers neutral may be quite different from the ground, so you should not go touching neutral wires unprotected. But it is generally not expected that it has the same powerful voltage as the hot wire.
- When current is passing through devices, it is quite visible. It is obvious that you shouldn't try to stick piece of wire into the housing of a lightbulb which is on. And indeed, when the switch is on, the entire circuit is dangerous.
- When the switch is off, there is no current, but the voltage still propagates through the parts of the circuit connected to the hot wire (and the grid). Those parts (before the switch) are very dangerous. The rest of the circuit (after the switch) is significantly less dangerous. If you put the switch on the neutral wire, then the dangerous part will include the device (eg. lightbulb). Unlike current, voltage is hard to see unaided, and with the switch open the lighbulb will appear to be off despite having a significant voltage. The moment someone touches the housing, the electrons will rush through that person to the ground, and electrocute them in the process. This is arguably a surprising result to most people, because they would not expect to be electrocuted when "the switch is off".
- For this reason, putting the switch on the hot wire improves safety in two ways:
- * Reduce accidents when people accidentally touch the contacts of an electrical device which is off
- * Doesn't mislead people into thinking a device is safe to work on "because the switch is off and the device seems unpowered"
#1: Initial revision
by
matthewsnyder
·
2023-07-06T04:42:43Z (over 1 year ago)
The switch will work either way. However, there are significant safety benefits to installing switches on the **hot** wire. In residential AC, only one wire actually has a potential difference (the "hot" wire, usually red or black) while the other wire is neutral (usually gray or white). Note that "neutral" is not the same as "safe to touch" - what the *grid* considers neutral may be quite different from the ground, so you should not go touching neutral wires unprotected. But it is generally not expected that it has the same powerful voltage as the hot wire. When current is passing through devices, it is quite visible. It is obvious that you shouldn't try to stick piece of wire into the housing of a lightbulb which is on. And indeed, when the switch is on, the entire circuit is dangerous. When the switch is off, there is no current, but the voltage still propagates through the parts of the circuit connected to the hot wire (and the grid). Those parts (before the switch) are very dangerous. The rest of the circuit (after the switch) is significantly less dangerous. If you put the switch on the neutral wire, then the dangerous part will include the device (eg. lightbulb). Unlike current, voltage is hard to see unaided, and with the switch open the lighbulb will appear to be off despite having a significant voltage. The moment someone touches the housing, the electrons will rush through that person to the ground, and electrocute them in the process. This is arguably a surprising result to most people, because they would not expect to be electrocuted when "the switch is off". For this reason, putting the switch on the hot wire improves safety in two ways: * Reduce accidents when people accidentally touch the contacts of an electrical device which is off * Doesn't mislead people into thinking a device is safe to work on "because the switch is off and the device seems unpowered"