Specification Sheet

ManualsBrandsLutron ManualsDimmersSkylark 600-Watt Single-Pole Slide-to-Off Dimmer - White

Minimizing Radio Frequency Interference (RFI)

Application Note #519

Revision D

June 2014

1 Technical Support — 800.523.9466

A solid-state dimmer is an electronic switch that rapidly turns the current on and off 120 times per second to achieve the

dimming effect. This rapid current switching may cause radio frequency interference (RFI) — an audible buzzing noise —

with sensitive audio and radio equipment. Although every Lutron® dimmer contains a ﬁlter to suppress RFI, applications

with sensitive equipment may require additional ﬁltering. Typical examples of RFI sensitive equipment are AM radios,

stereo sound systems, broadcasting equipment, intercom systems, public address systems and wireless telephones. RFI

can be transmitted in two ways:

• Radiated

• Conducted

Radiated RFI

All wiring that carries dimmer-controlled current can act as an antenna to radiate RFI into the air waves. Any sensitive

equipment that is in close proximity to this wiring can pick up the RFI and generate noise into its system. Also, this could

occur if the wiring for sensitive equipment runs along side the wiring for the dimmer.

Example of Radiated RFI

The following are three possible ways to minimize radiated RFI:

• Physically separate the RFI sensitive equipment from the dimmer and dimmer wiring.

• Run dimmer wiring separately in a metal conduit.

• To ﬁlter the RFI, use a lamp debuzzing coil (LDC) available from Lutron. See next page for more details.

Intercom

Dimmer

Distribution

Panel

Radio

Wiring

Summary of content (4 pages)

PAGE 1
Application Note #519 Minimizing Radio Frequency Interference (RFI) Revision D June 2014 A solid-state dimmer is an electronic switch that rapidly turns the current on and off 120 times per second to achieve the dimming effect. This rapid current switching may cause radio frequency interference (RFI) — an audible buzzing noise — with sensitive audio and radio equipment. Although every Lutron® dimmer contains a filter to suppress RFI, applications with sensitive equipment may require additional filtering.
PAGE 2
Application Note #519 Conducted RFI In some cases, RFI is conducted through the building wiring and directly into the AC power supply of the sensitive equipment. Example of Conducted RFI Dimmer Intercom Wiring Stereo Distribution Panel Recommendations Lutron recommends the following methods to avoid RFI. • Feed sensitive equipment from a circuit without a dimmer on it. • Add a power-line filter to the sensitive equipment.
PAGE 3
Application Note #519 Lamp Debuzzing Coils (LDCs) 1 The most effective way to reduce RFI is to install an LDC into the lighting circuit. When an LDC is wired in series with the dimmer, it slows down the inrush of current during the rapid switching cycle of the dimmer. As the current inrush is slowed down, the effect of RFI on sensitive equipment is reduced. Lutron has four LDC models available to help reduce RFI. The type of LDC required depends on the total wattage of the lighting load.
PAGE 4
Application Note #519 Lutron is a trademark of Lutron Electronics Co., Inc. Lutron Contact Numbers WORLD HEADQUARTERS USA EUROPEAN HEADQUARTERS United Kingdom ASIAN HEADQUARTERS Singapore Lutron Electronics Co., Inc. 7200 Suter Road Coopersburg, PA 18036-1299 TEL: +1.610.282.3800 FAX: +1.610.282.1243 Toll-Free: 1.888.LUTRON1 Technical Support: 1.800.523.9466 Lutron EA Ltd. 6 Sovereign Close London, E1W 3JF United Kingdom TEL: +44.(0)20.7702.0657 FAX: +44.(0)20.7480.6899 FREEPHONE (UK): 0800.282.