Is the use of a contactor required if a mechanical timer which normally opens the coil on a contactor feeding the load is suitable for switching the load anyway.

The load: 2 off 1000Watt HPS ballast lighting units totalling 10Amps.

I want to control the duty cycle of the load by using a mechanical timer which is rated to switch 10Amps of inductive load.
My friends put a contactor or relay in circuit and have the timer fed from the mains open the coil on the contactor and have a seperate supply from the mains feeding the load once the timer has opened the contactor.
Is this realy neccessary ? I can understand a contactor being used in circuits with loads greater than the mechanical timer is rated for but if the load is the same or less than the current carrying capacity of a switching device allready in circuit ie the timer, whats the point.
Also whats the differance between a contactor and a relay ?

Please help

 

Generally, the timer contacts are only designed for pilot duty, even though they are rated at 10 amperes. The contactor's contacts are much heavier metal and the gap is wider allowing better switching characteristics and arc suppression. A visual inspection will confirm this. The voltage rating is greater; 600 VAC where the timer is probably 250 VAC.

 

Use the contactor, having the Fire Department finding your grow room will ruin your day!!!

 

Thanks so much for your response Duane & Shortbus this answers my question, whould you recomend using a relay or contactor in circuit.