Why do I have two black wires on my light switch?

Asked By: Basili Gabernet | Last Updated: 26th March, 2021
Category: hobbies and interests jewelry making
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Black means hot, white signifies neutral, and green indicates ground. However, if you need to rewire a light switch or a plug socket, you may occasionally come across two black wires. It's essential that you determine which black wire is hot before proceeding.

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Considering this, why does light switch have 2 black wires?

The bare or green-wrapped ground wires serve as a backup to divert the power safely away in case of an electrical fault. In most cases, two black wires will be attached to the switch's two terminal screws.

Beside above, why do I have 3 black wires on my light switch? If the light turns on, the second black wire you connected to the switch is the switch feed and the unconnected black wire is the feed to the other loads. If the light doesn't turn on, then it's the other way around: the connected wire feeds the other loads and the disconnected wire is the light feed.

Besides, how do you wire a switch with two black wires?

If the switch box wiring has a bare ground wire, connect it to the green terminal screw on the switch. Connect the two hot (black) wires to the two brass terminals on the new switch. Gently push the new switch back into the box. Fasten the switch to the box with the two long screws at the top and bottom of the switch.

Does it matter which wire goes where on a light switch?

If your switch has a “LINE” marking, the always hot wire goes to this. The other connection will be “LOAD” where the load (ie light fixture) is wired. The load wire may have red electrical tape on it to differentiate.

37 Related Question Answers Found

How do you tell which wire is hot if both are black?

Place the prong of the multimeter's black wire on the bare metal on the end of a white wire, then read the meter. If you get a reading, the black wire is hot; if you don't, the black wire isn't hot.

Which wire is hot if both are black?

know what each color of wire does in the circuit
The black wire is the "hot" wire, which carries the electricity from the breaker panel into the switch or light source. The white wire is the "neutral" wire, which takes any unused electricity and current and sends them back to the breaker panel.

What happens if you wire a light switch wrong?

If either wire at the light fixture is still hot then the switch is wired incorrectly. If one of the wires is still hot at the light fixture with the switch in the off position, then you most likely have the light switch on the neutral wire. Separate the bare ends of the wires so you can safely turn the power back on.

Will light work if wired backwards?

The fixture still works if you reverse the wires, but the socket sleeve will be hot, and anyone who touches it while changing a bulb can get a shock. When wired correctly, the socket sleeve is neutral and only the small metal tab at the base of the socket is hot.

Which wire is live red or black?


You can clearly see that red is connected to the new brown (live), black is connected to the new blue (neutral) and the green and yellow earth stays the same.

What happens if you switch hot and neutral wires?

The neutral wire is connected to ground at the breaker box, which is connected to physical ground nearby. If you switch the hot line and leave the neutral, then the whole device will be at neutral potential. However, stuff happens, and by switching neutral instead of hot you have removed one layer of safety.

Can I connect red and black wires together?

In 220-volt circuits, red wires are the secondary live wires. Like black wires, they can be used in some types of switch legs. It's possible to link two red wires together or a red wire to a black wire.

What happens if you connect white wire to black wire?

Inside an outlet's electrical box, the black (hot) wire should be connected to the brass-colored terminal on the outlet. The white (neutral) wire should be connected to the silver-colored terminal. If these connections are backward, the polarity is wrong.

Why does my outlet have 2 black and 2 white wires?

Since this one has more, it means it is part of a "series". A "series" means there are 2 or more outlets powered by the same wiring and circuit. The other set of black and white wires goes to the next outlet down the line and that's how it gets its power.

How do you wire a light switch with a black and white red wire?


First, twist the two bare copper ground wires together. Twist the two red wires together and attach a wire nut. Take the white wire from switch two and twist it with the black wire from switch one. Mark the white wire with a piece of electrical tape to indicate that the wire is now a hot wire.

Why does my light switch only have two wires?

Yes, this is normal. There are two ways to wire a two-way switch with 2-core cable like you have: This is how your switches are wired. As you can see from the diagram, the white wire is used -- it completes the circuit back to the electrical supply's neutral line.

How do you wire an outlet with 3 black and 3 white wires?

Connect all three black and fourth short black wire(pigtail) with a wire nut. Then connect the pigtail to the gold screw. Do the same with the white wires only connect to the silver screw. Buy receptacles with back wire connectors.

What is common wire?

A common wire is a more general term and simply refers to the 0 Volt wire of a circuit, either electrical or electronic.

What is a double pole switch?

Poles: A switch pole refers to the number of separate circuits that the switch controls. A single-pole switch controls just one circuit. A double-pole switch controls two separate circuits. A double-pole switch is like two separate single-pole switches that are mechanically operated by the same lever, knob, or button.

Do I need an electrician to replace a light switch?


If you have a light switch that no longer works, it needs to be replaced. Unless you are unfamiliar with electrical work, it's wise to bring in a professional. An electrician can help make wiring a light switch hassle-free. He'll also be able to install an upgraded light switch that can make your life a little easier.

Does a single pole switch need a neutral?

To wire a single pole switch using a regular switch leg, you need power and a neutral at the switch box. You do not need regular power or neutral at the box of the device being switched.

How do you wire a light switch and outlet in the same box?

Connecting Separate Devices in a Double-Gang Box
The same three options exist when wiring separate devices. To have the switch control just the outlet, connect the hot circuit wire to one of the switch terminals, and then connect the other switch terminal to the brass terminal on the outlet with a short jumper wire.