Magnetic Fields from Three – and Four-Way Switches

Lights switched from two different locations are called three-way switches. When lights are switched from three or more locations, they

A: 1/2 switched outlet. Both hot and neutral pre-scored conduction tabs must be snapped off when the upper and lower outlets are supplied by separate breakers.

B: Ganging Neutrals. This wiring configuration is wrong and will create net current and magnetic fields.

C:This diagram shows the correct configuration, which will not generate magnetic fields.

2 fomex

1 hot"

I neutral J ground

Properly wired З-way switch.

are called four-way switches. A correctly wired three – or four-way switch will not emit mag­netic fields. However, these switches are often wired incorrectly and thus become a source of magnetic fields that can radiate throughout the room. To avoid improperly wired three – or four-way switches, specify the following:

• Three-wire Romex shall be used between the switches when wiring a three-way switch (see illustration). If alternate wire is used, it shall be twisted.

• Each three – or four-way switch must be controlled by a single breaker.

• All wiring for three – or four-way switches shall be contained in a single run of wire or a single metal conduit. All runs not in a conduit must be bundled.

Fields from Dimmer Switches

Dimmer switches are a source of magnetic and radio frequency fields. If these switches are used, they should be located at a distance from seating and sleeping areas. The most ex­pensive name-brand dimmers tend to emit smaller fields. Choose a model that emits no fields when all the way on or all the way off.