Q: I have a problem with the relays and contactors I've been using to control lighting circuits in my building. They seem to fail often, usually with burned and pitted contacts.

A: It might not seem like it, but those small ballasts we use to start and run fluorescent lamps present quite an inductive load to an AC electrical system. Just like an induction motor, there is a very high inrush current when the contacts close and a tendency to draw an arc through the air when the contacts open under load. The newer electronic ballasts are a little kinder and gentler but not much. Even incandescent lamps (tungsten) can be cruel to a contactor - when the lamps are cold, they present a very low resistance and thus can have an even higher inrush current than fluorescents. Most definite-purpose and motor-duty contactors are not rated for this type of service, and their manufacturers usually make special lighting versions with heavier duty contacts. The solution is to make sure your contactor or relay is fully rated for the ballast and tungsten loads it will handle. The RCB-8, TR Series, SH17 Series, RR-7, RR-9, and other products found in the Lighting Controls section of the Kele Catalog will keep you out of the dark!