Lamp Wiring Diagrams
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–Most wiring diagrams on this site include a green dot representing the integrated grounding terminal found in most metal outlet boxes. However, some older metal boxes and most plastic boxes don't have a terminal like this.
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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
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 Push-Button Lamp Switch
Here a 2-way push-button switch is wired to a lamp with 2 bulbs. This diagram can be used to rewire an old push-button lamp with a new switch replacement. The hot wire from the cord is connected directly to the black wire on the switch and the neutral is spliced to the neutral contact on each bulb sockets. The red and blue wires from the switch are each connected to the hot contact on one of the bulb sockets.
Wiring a 3 Way Lamp Switch
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
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
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.