Re: Relay life-time
eem2am,
In general, it is not possible to control the switching of an electromechanical relay so that it only switches at zero crossing because the response time of the relay is so slow. You can increase the life of a relay by using a relay that has a current rating much higher higher than the expected peak current.
Regards,
Kral
Added after 2 minutes:
An excellent reference for relay applications is "Engineers' Relay Handbook" published by National Association of Relay Manufacturers.