Lamp Switch Wiring Diagrams

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–Check local regulations for restrictions and permit requirements before beginning electrical work–

This page contains wiring diagrams for four different types of lamps. Included is a diagram for a two-circuit lamp switch to control a standard incandescent bulb on top of the lamp and a smaller, low wattage bulb in the base. Also include are diagrams for a standard one setting lamp, a three way lamp and an antique floor lamp with 4 light bulbs.

Finding Lamp Cord Polarity

Lamp cords are usually one color, making the standard black-hot, white-neutral guidelines useless for determining polarity. Other methods are therefore used to determine the polarity on a lamp cord. Check the insulation on the cord wires closely and you will find either a textured bead or a thin colored line running along one wire, this is the neutral. The plain wire is the hot. If the cord isn't marked with a bead then the strands of wire will be different colors. In these cases the silver wire is the neutral and the brass colored wire is the hot. The plug on the lamp cord holds another clue to polarity with the wide prong being the neutral and the narrow one the hot. Older lamp cord will have prongs that are the same size. This is because polarity was not observed on electric lamps until the development of grounded circuits.

Wiring a 2 Way Lamp Switch

wiring a 2 circuit lamp switch

This diagram illustrates the wiring for a bedside lamp with two sockets. The top socket A, holds a standard incandescent bulb. The second socket B, typically holds a small, low-wattage bulb similar to a night light bulb. The switch allows for energizing the top bulb only, the night light only, both bulbs at once or for turning both bulbs off. This type of switch will be referred to as a 2 circuit lamp switch when shopping at home stores. Don't mistake this for a three way switch (pictured below), the two do not function in the same way.

Wiring a 3 Way Lamp Switch

wiring a 3 way lamp

Above is a wiring diagram for a standard, 3-way lamp switch. This socket is used with a three way bulb containing 2 separate elements that are energized separately and then together as the switch knob is turned, for varying degrees of light. These sockets have two terminals, one for the hot wire and one for the neutral. A third contact may be present but is not used for this circuit.

Wiring a Lamp Switch

wiring a lamp switch

This diagram illustrates wiring for a standard, one setting lamp. This socket has two terminals, the brass for hot and the silver for the neutral wire.

Wiring a Floor Lamp Switch

wiring a floor lamp switch

This is a wiring diagram for an antique floor lamp with 4 bulbs, one main bulb and 3 peripheral, and usually smaller bulbs. The main bulb threads into a standard socket with an integrated switch and the three peripheral bulbs are wired to a single switch. The secondary switch may have wires colored black, blue and red or, if it's an old switch, other colors or texturing may be used to distinguish them.

With this lamp, bulb A can be turned off and on independently and switch B can turn on bulb 1 alone, bulbs 2 and 3 together with bulb 1 off, bulbs 1, 2 and 3 all on at the same time or all three off.

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