Why do I have a voltage reading when light switch is off?

Just to recap, a “phantom voltage” is where a wire from a switch to a light or outlet runs next to a permanently live wire, when the switch is off, the AC voltage in the other wire can induce a voltage in the switched-off wire.

Does current flow if switch is off?





Generally electrical current requires a close path or circuit to flow, so when switch is off it won’t flow.

Is phantom voltage a problem?

This is what is referred to as a “phantom” voltage. According to Underwriters Laboratories Inc., this can be a harmless reading and can be caused by the high input impedance of the measuring instrument, which places very little loading on the circuit under test.

How do you troubleshoot a 3 way switch?

Quote from the video:
Quote from Youtube video: Taking the plate off and pulled out the switch. The power originates from this location. And everything looks great okay however over here I found a problem.

What causes backfeed voltage?

Backfed voltages are voltages that often originate from another circuit or part of the equipment, but “backfeed” through indicating lights, control power transformers or even resistors in equipment.

Why is there voltage on the neutral?





The voltage you are seeing on the neutral wire is conducting through that other load from the hot. Your voltage tester is detecting voltage without drawing current so the resistance of the other load is not seen. Try disconnecting/turning off all other loads on that circuit.

How does the switch turn the current on and off?

With a zero signal applied to the Base of the transistor it turns “OFF” acting like an open switch and zero collector current flows. With a positive signal applied to the Base of the transistor it turns “ON” acting like a closed switch and maximum circuit current flows through the device.

What will you observe when the current is switched on and switched off?

Explanation: When current is switched on and switched off in a coil a current will be induced in the other coil kept near to the first coil, this happens due to the electromagnetic induction.

When the switch is closed the current in the circuit I is?

When a switch is closed, the current built up in an electric circuit is given by E=Ri+Ldtdi.

What happens if you wire 3-way switch wrong?



If you don’t correctly connect this wire, then your lights won’t work from more than one switch. Grounding the switch: You’ll also need to locate the ground wire and connect it to the switch too.

Is there always a hot wire on a 3-way switch?

Black wire: This is a hot wire that carries electricity from the power source to the first switch in a typical 3-way setup. It’s also called the “common wire” or the “line wire.” Unless the breaker is off, this black wire is always hot.

How do I know which wire is common on a 3-way switch?

Quote from the video:
Quote from Youtube video: If no house current is found on any of the three wires. Go to the other switch. And do the same thing one of the wires will have house current and that wire is the hot wire mark.

What color wires go on a 3-way switch?



3-Way Switch Wire Colors



There is no standard for wire colors on 3-way switch travelers. The colors will vary depending on whether NM cable or conduit was used. With NM cable, the wire colors for travelers will be black and red using 3-wire cable. With conduit, the wire colors for travelers could be any color.

How do you check continuity on a 3-way switch?

Test a 3-Way Switch

  1. Turn off power to the switches at the circuit breaker and using a tester, make sure power is off. …
  2. Using a continuity tester, check continuity between the common (black) terminal and each of the traveler terminals (brass colored) of each 3-way switch.

What color wire goes to the black screw on a 3-way switch?

Tighten the terminal screws. Connect the ground wire to the green screw, then connect the wire marked common to the black or dark colored screw. Connect the two remaining traveler wires to the two brass or light colored screws.

At what terminal of 3-way switch we connect wire going to the load?

common terminal



The common terminal is the “bridge” between the power supply and the load (typically a light fixture). With this in mind, the wire that attaches to the common terminal is either (1) a hot wire from the main board or (2) leads to the load (fixture).

Which wire is neutral on a 3-way switch?

white

The other wires in a circuit with 3-way switches are the neutral (usually white) and ground (usually bare copper or green). The neutral wire bypasses both 3-way switches but connects to the light fixture. The ground connects to the ground terminal on each switch and to the light fixture.

Do 3-Way switches always have neutral?

The most common wiring requirements of any hardwired automated 3-way light switch is a neutral wire and a traveler. Yes, there are a few… (read very, very, very few) switches that don’t require a neutral, but those will limit you to incandescent only.

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.