Answer for USA, Canada and countries running a 60 Hz supply service.
In normal operating conditions, whenever there is a load on the circuit, the white wire - which is called the "neutral" - returns the current coming out of the load back to the power station.
The "hot" wire supplies the current coming from the power station to the load.
In residential wiring, convention is that the black wire is "hot" and the white wire is "neutral". This means that, if the circuit is wired correctly - and there is no fault in the circuit - the white wire should not have any potential difference (voltage) relative to ground.
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As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed.
Before you do any work yourself,
on electrical circuits, equipment or appliances,
always use a test meter to ensure the circuit is, in fact, de-energized.
IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB
SAFELY AND COMPETENTLY
REFER THIS WORK TO QUALIFIED PROFESSIONALS.
In 110 volt applications with three wires, black is the hot wire, white is the neutral, and the bare copper is the ground.
However sometimes in 220 volt applications with three wires both the black and the white are the hot wire and the bare copper is the ground, this happens when a contractor does not use the properly colour coded wire for 220 volt applications.
When in doubt always use a volt meter to test each wire.
The white wire is always identified as a neutral wire. The only time you will find the white wire "hot" is in residential home wiring. This will be the return wire from a light switch back up to the light fixture. Code specifies that this conductor has to have a coloured tape identifier to show that it is not a neutral but a current carrying "hot" conductor.
The only safe answer to your question is "yes." The black or the white or both are "hot."
If wired properly, only the black wire will be hot. That's a big "if." In many instances, people will take shortcuts or simply do the work wrong. To be save, get yourself a voltage sensor. They're somewhere around $20 and commonly available.
When properly wired, sometimes the white wire can be hot, but each end of it should be wrapped in black electrical tape.
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Correctly wired the black is the "hot" wire and the white is the neutral wire.
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In North America on a single phase service the red and black wires are hot resulting in 240 volts. Either of these two wires and the white coloured neutral will produce 120 volts. On a three phase four wire system in Canada the colour coding is red, black, blue and white for the neutral. In the US the colour coding is black, red, blue and white for the neutral.
You have a 3 way switch. Your black wire is the hot wire. Your green wire is the ground wire. Your red and white wires go to the light and other switch. You should have gotten a wiring diagram with your switch.
If the house wiring does not have a white wire, you can cap off the white wire from the track light with a wire nut and electrical tape if necessary. The white wire is typically used as the neutral wire, but if it's not present in your house wiring, capping it off safely will ensure the track light functions correctly with the available black and green wires.
The red wire is typically used as the live wire in an electrical circuit. In a three-wire setup with black, red, and white wires, the black wire is usually the hot wire, the red wire is also a hot wire, and the white wire is the neutral wire. The red wire can be paired with the black wire to supply power to a specific device or component.
The green or bare wire is typically the ground wire for a dryer plug. If your wires are black, white, and red, the white wire is usually neutral, the black is hot, and the red is also hot. You should double check with a voltage tester to be certain.
In standard residential wiring, the black wire is typically the hot wire, regardless of whether it is striped or solid. The white wire is the neutral wire, and the green or bare wire is the ground wire. It is important to consult a professional electrician or local electrical codes for specific wiring configurations.
the black wire is the hot wire
You have a 3 way switch. Your black wire is the hot wire. Your green wire is the ground wire. Your red and white wires go to the light and other switch. You should have gotten a wiring diagram with your switch.
If this is a home wiring question and the wires are black and white then black is Hot and white is Neutral. If you also have a red wire, it is the other hot wire, and either the black or the red wire to the white one would be 120 volts, and red to black would be 240 volts.
If the house wiring does not have a white wire, you can cap off the white wire from the track light with a wire nut and electrical tape if necessary. The white wire is typically used as the neutral wire, but if it's not present in your house wiring, capping it off safely will ensure the track light functions correctly with the available black and green wires.
The last fixture in a parallel circuit is wired the same as the first. In North America, all of the fixtures are wired black wire to black wire and white wire to white wire. The black wire being the "hot" wire and the white wire being the neutral wire.
Black Wire from photocel to hot wire(black) coming in red wire to light fixtures black wire. White wire to neutral wires all light and power source white.
In most circumstances and electrical schematics L1 is black and L2 is white. L1 is usually the "hot" wire and L2 is the "neutral".
Your black wires are your hot wires. The white is your neutral or common. It would be best to run an equipment ground (green wire) too.
The red wire is typically used as the live wire in an electrical circuit. In a three-wire setup with black, red, and white wires, the black wire is usually the hot wire, the red wire is also a hot wire, and the white wire is the neutral wire. The red wire can be paired with the black wire to supply power to a specific device or component.
Black is hot and white is neutral. If you are switching something you switch the black, so that is what you would cut.
The green or bare wire is typically the ground wire for a dryer plug. If your wires are black, white, and red, the white wire is usually neutral, the black is hot, and the red is also hot. You should double check with a voltage tester to be certain.
In standard residential wiring, the black wire is typically the hot wire, regardless of whether it is striped or solid. The white wire is the neutral wire, and the green or bare wire is the ground wire. It is important to consult a professional electrician or local electrical codes for specific wiring configurations.