Why Are White Wires On My Light Switch (2022)

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Why Are White Wires On My Light Switch (1)

Why White Wires are Sometimes Used for Light Switches: Wiring Light Switches with White Wires


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Wiring Light Switches with White Wires
Electrical Question: I am changing out a ceiling fan and wall switch.

  • When I pulled the existing switch the White wires (I assume they were neutral wires) were connected to switch.
  • This made me nervous and I wanted to double check which wire was hot.
  • So I tested the wires – Hot to Neutral 125v, Hot to Ground 35v, Neutral to Ground 30v.
  • I opened every other box I could find on this circuit and they seem OK (I checked wire nuts, screws), tested one of them and got 125volt.
  • I did not find the feed wire to my fan switch in the other boxes though, it’s a blue Romex and the only ones I found were white. Any suggestions? Is this dangerous?
  • Attic access to this spot is very difficult and unbearably hot in Florida during the summer even at night (trust me I did it last Sunday night).
  • The previous fan installed by a previous owner was still functioning after about 20 years.

Background: Bill, a Handyman from South Florida.

Dave’s Reply:
Thanks for your electrical wiring question Bill.

Why White Wires are Sometimes Used for Light Switches

At times, we still find in some older homes that White Wires are used for wiring light switches, and the light switch wiring method is different, however we also find White Wires being used today for wiring light switches however the method is entirely different.

  • Some older homes were wired where the Neutral was switched, not the hot, and thank goodness that is not the practice today.
  • However many times an electrician will use a white wire as a switched leg, but when this practice is used the wire should be identified with black electrical tape.
  • The 35 volt reading form hot to ground should be checked. This is sometimes an indication of a neutral feedback when one of the main power legs is lost on a 240 volt service, but this may also be an indication that the neutral wire is being switched, and you may find that when the switch is in the ON position this voltage reading will change to zero or 120 volts, factors within the circuit will affect this including the type of light bulbs that are used in the light fixture.
  • This may or may not be the case with your situation, to know for sure you should have a qualified electrician perform a few tests that would reveal the condition.

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FAQs Frequently Asked Questions and Comments

2 Responses to “Why Are White Wires On My Light Switch”

  1. Greg says:

    March 24, 2014 at 6:51 pm

    (Video) How To Wire A Single Pole Light Switch

    I was just reading this article as I also was going to switch out some old switches to more modern light switches. When I pulled out the existing switch I noticed I have 2 black wires and a white wire connected to the old switch. I tried to figure out the path of power but I wasn’t getting the readings I was expecting. The old switch had 3 screws on it. 2 light brass and 1 dark brass named “common”. The ground is screwed into the box so I understand that. The dark brass had the main power connected to it.

    I tried to find continuity to the light this switch operated but I could only find it with the white wire. The black wire from the light to the light switch did not make my meter beep so I am not sure where it goes. There is also some other things in that light box I am not understanding. The switch mounting box is made for a double light switch but only has 1 switch mounted in it. It looks like the previous owner of this house just put putty over the other half. But in that box there are 3 sets of wires going into the box, there are red and white wires twisted together, white and black twisted together, and actually the main power wire going to the light switch I am wanting to change which has a black wire, white wire and a little single lead wire going to this light switch twisted together.

    Why do I have white wires twisted with black wires, why is there a white wire going to this light switch? Do I have a 3 way switches in there?

    Thanks Greg

  2. Dave Rongey says:

    March 25, 2014 at 2:05 am

    Hi Greg,
    From what you have described the existing switch is a three way switch. White wires are often used for switching, however the white wire should then be identified with black electrical tape or a permanent marker. If the wiring does not appear to be correct then the wiring should be traced out and identified and corrections made as needed.
    I hope this helps,
    Dave

    (Video) Understanding an Open or Loaded Neutral

FAQs

Why is a white wire connected to light switch? ›

The black wire is the "hot" wire, it carries the electricity from the breaker panel into the switch or light source. The white wire is the "neutral" wire, it takes any unused electricity and current and sends it back to the breaker panel.

What do you do with the white wire on a light switch? ›

The white or neutral wire bypasses the switch and goes straight to your lights. This wire is needed to complete the circuit. The ground wire (sometimes in a green jacket) should be connected to your switch and to your lights.

What do you do with a neutral wire in a light switch? ›

The neutral wire or blue wire bypasses the light switch and reaches directly to the light fixture. This wire is required to complete the electrical circuit. The copper brass or yellow/green coloured ground wire must be connected to the light switch and the light.

When wiring a switch the white wires are connected? ›

In the first switch box (the box where the power comes in), you'll see eight wires. Two white (neutral wires) will be connected and covered with a wire nut. A black wire will be connected to a black or copper screw terminal—this is the “common” wire—and you must distinguish it from the other wires.

What happens if you connect the wrong wires in a light switch? ›

But here's the catch: If you connect the circuit wires to the wrong terminals on an outlet, the outlet will still work, but the polarity will be backward. When this happens, a lamp, for example, will have its bulb socket sleeve energized rather than the little tab inside the socket.

Is the white wire necessary? ›

As you can see, the neutral wire is essential to your home's electrical system. Without it, there would be no circuit for electricity to flow along and complete its circle back to the power source.

Could I use the white wire for black? ›

The term “hot” means these wires carry a live current from your electric panel to the destination. While white wiring is permitted— only when clearly marked with black or white tape—using any other color for a wire carrying current is strongly discouraged.

Does it matter where the wires go on a light switch? ›

Because the switch terminals are interchangeable, it doesn't matter which wire you put on each.

Does the white wire connect to black or red? ›

Does The Red Wire Connect To Black Or White? Since the white wire is neutral, you should never connect a red wire to the white. However, you may connect the red wire to the black since they are both hot wires.

Will a switch work without a neutral? ›

Absolutely! Even if you have a smart switch no neutral, you can install it. That's because most modern smart switch brands don't require a neutral wire. Older homes typically don't have a visible neutral wire in the wall socket.

What happens if you don't connect a neutral? ›

Without the neutral wire, all sorts of instabilities occur in the system like unstable voltages, unexpected currents and even dangers of electric shock.

Do you have to connect a neutral wire to a light switch? ›

A neutral wire is required to install a Brilliant Control. Normal electrical switches do not consume any power - they simply connect the power line to the light bulb. The Brilliant Control requires power, and power has to flow from the power line through the Brilliant, back out through the neutral.

Does white wire go on top or bottom of switch? ›

Hook the bare wire to the box and to the switch. Hook the black wire to the bottom terminal on the switch. Hook the white wire to the top terminal on the switch. Push the switch into the box and secure it with screws at the top and bottom.

Where do I connect the white neutral wire? ›

Neutral wire carries the circuit back to the original power source. More specifically, neutral wire brings the circuit to a ground or busbar usually connected at the electrical panel.

Why is white wire hot in switch? ›

Although there could be an “open neutral” return to the breaker panel, or klutzy mis-wiring, the most likely cause of a hot white wire connected to 3 & 4-way switches is that it was used as part of the switched “hot” circuit.

How do you know if a light switch is wired correctly? ›

Test for Power

Remove the screws on the switch cover plate, and pull off the cover plate to expose the switch wiring. Without touching any wires, test each wire in the electrical box with a non-contact voltage tester. Also, test each of the side terminals on the switch by touching it with the tip of the tester.

How do you know if a light switch is wired 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.

How do you tell if a light is wired backwards? ›

Touch one probe of a voltmeter to the top of the bulb socket sleeve (not the small metal tab inside the socket) and the other probe to the circuit ground wire and have a helper turn on the power at the service panel. If the meter indicates positive voltage, the wires are reversed.

Can the neutral wire shock you? ›

The neutral wire does have current going through it. However, we do not get shocked when we touch something with current going through it, we get shocked when current goes through us.

Is there voltage on the white wire? ›

The neutral wire is often said to have zero voltage on it.

Can white wire be live? ›

Typically, white wires are neutral wires. However, in some cases, the white wire is modified by adding red or black tape to it. This modification signifies that the cables are being used as a live wire, and they should be handled with caution.

What happens if I mix up black and white wires? ›

If the system is “live” you will likely produce a moderate to serious spark and the breaker supplying power to the wires will trip. If the system is off (breaker in off or tripped position) then nothing will happen until you turn the power back on. The breaker will instantly trip as soon as you attempt to turn it on.

What happens when you touch a black wire to a white wire? ›

If you come in contact with an energized black wire—and you are also in contact with the neutral white wire—current will pass through your body. You will receive an electrical shock. You will receive a shock if you touch two wires at different voltages at the same time.

What does white wire connect to? ›

A white neutral wire usually connects to a silver-colored terminal or white wire lead. A green or bare ground wire almost always makes a ground connection—to a ground screw on a device, electrical box, or appliance case or to a green wire lead.

What Colour is live wire in light switch? ›

The live wire is Brown

This replaces the old colours of red (live) and black (neutral) and green (earth) which changed back in 2006.

How many wires should a light switch have? ›

Three wires will be attached to your switch: a hot (black) wire, a neutral (white) wire and a ground (copper) wire. The black and white wires are attached using brass screws.

Which wire is common on light switch? ›

Changing a light switch

"COM" or "Common" is the terminal to which the live core wire is attached - this is the brown wire (formerly red).

Which wire is live red or white? ›

US AC power circuit wiring color codes

The protective ground is green or green with yellow stripe. The neutral is white, the hot (live or active) single phase wires are black , and red in the case of a second active.

What color wires go together for a ceiling light? ›

Connect the wires as they were in the old fixture.

The ground wire is the bare copper wire and should be connected to the green grounding screw in the crossbar. Wire black to black (hot) and white to white (neutral), and make sure that all connections are snug.

WHAT TO DO IF switch has no neutral? ›

What to do if you don't have a neutral?
  1. Install neutral wire. You can add neutral wire to your smart switch no neutral, but you need to do re-work inside your walls. ...
  2. Use smart bulbs instead. ...
  3. Buy a smart switch no neutral wire.

What happens if I wire live to neutral? ›

When live wire comes in contact with the neutral wire, then the insulation of wires is damaged or there is a fault in the appliance. In such a situation, the current in the circuit abruptly increases. This is known as short circuiting.

Does every switch have a neutral wire? ›

If your house was built in the mid-1980s or later, you should have neutrals everywhere in your house. Houses built before that may or may not have a neutral wiring. If there is an outlet (wall receptacle) near the switch, most likely that switch has a neutral.

Does the neutral wire carry voltage? ›

Neutral and grounding wires are often confused outside of the electrical trade, since both conductors have zero voltage. Actually, if you connect the grounding wire as a neutral by mistake, most devices will operate correctly.

Why do you bond the neutral to ground? ›

The Answer:

Neutral-to-ground bond is needed to properly operate the circuit breakers. Over Current Protection Devices (OCPD) such as circuit breakers and fuses actually require a short and intense INCREASE in electrical current (a short) in order to detect the fault and cut the circuit off.

Where does the white wire go on a 3 way switch? ›

Three-way wire(which includes red, black and white wires) runs from the switch on the left to the switch on the right, with the white wire carrying ground and the red and black wires carrying the output from terminals in the left switch.

Where does the black and white wire go on a switch? ›

You connect the black wires in the electrical box to the switch terminals, and the white wires to each other. The switch also has a green terminal for the ground wires, which usually are bare.

What will happen if hot and neutral wires reversed? ›

One common issue with electrical outlets is reverse polarity, also known as "hot-neutral reversed." In this condition, the outlet has been wired incorrectly, altering the flow of electricity. While the outlet will still be able to provide power to your electrical items, it is also present a greater shock hazard.

What Colour wires are neutral and live? ›

Plug wiring colours
WireColour
LiveBrown
NeutralBlue
EarthYellow and Green

Should a white wire ever be hot? ›

The black wire is the "hot" wire, it carries the electricity from the breaker panel into the switch or light source. The white wire is the "neutral" wire, it takes any unused electricity and current and sends it back to the breaker panel.

Can I use white wire as hot? ›

The term "hot" is used for source wires that carry power from the electric service panel to a destination, such as a light or an outlet. Even though you are permitted to use a white wire as a hot wire by marking it with electrical tape, the opposite is not recommended or allowed.

Is white wire heat? ›

The wires are typically arranged as follows: red for 24-volt hot, white for heat, yellow for cooling, green for the fan, and blue for common (although the common wire may be a different color).

What does white wired mean? ›

White or gray wires indicate neutral charged wires. However, neutral wires may carry power and pose a danger of electrocution if not handled properly. White and gray wires carry power back to the service panel. Both hot and neutral wires have the potential to shock and injure you if not handled properly.

Why does my neutral wire have voltage? ›

If neutral wires are not connected to the ground then an electrical charge can pass through it.

Is white wire ever positive? ›

The white wire is neutral. Neutral is distinct from ground in AC wiring. The green wire (if present) is the ground wire.

Are white wires ever hot? ›

Sometimes a white wire is used as a hot wire—not a neutral—in a switch leg, or switch loop, between a switch and a light fixture.

Can a live wire be white? ›

Typically, white wires are neutral wires. However, in some cases, the white wire is modified by adding red or black tape to it. This modification signifies that the cables are being used as a live wire, and they should be handled with caution.

Is white wire hot or load? ›

Blue and yellow wires are hot wires for ceiling fans and three- or four-way switches. White or gray electrical wires are neutral wires.

Should white wire have voltage? ›

The neutral wire is often said to have zero voltage on it.

Can a white neutral wire shock you? ›

The neutral wire does have current going through it. However, we do not get shocked when we touch something with current going through it, we get shocked when current goes through us.

What happens if neutral wire has current? ›

When live wire comes in contact with the neutral wire, then the insulation of wires is damaged or there is a fault in the appliance. In such a situation, the current in the circuit abruptly increases. This is known as short circuiting.

Does a white line mean positive or negative electrical? ›

The neutral wire will typically be white. This is the path where any electricity that is not used by the equipment will travel back into the electrical system.

How can I tell which wire is positive and negative? ›

The Different Types of Wire Color Codes
  1. The positive current must be red.
  2. The negative current must be black.
  3. The ground wire, if present, must be white or grey.
19 Apr 2022

Does white go to black wire? ›

As one uses a two conductor cable to connect the switch to the fixture box, the white switched wire in that box will connect to the black wire of the lamp.

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