contraptionated
New Member
It should be known that it is not enough information to only know the ampere rating of the contacts when selecting a lighting contactor. Unless you want the contacts to weld closed without notice, you must know the shutoff capacity of the contacts, otherwise referred to as current on break. The breaking (or disconnecting) capacity is always much, much lower than the full load rating (in this case the contactor in question has a 30 amp rating) and because you would be loading each contact to roughly 27 amps (if you take Stevie51's advice and use a DPST relay in the way you mentioned [6-240V outlets on each pair of contacts] you would definitely be expecting the contacts to eventually fail from repetitive excessive arcing.Hot Tubs and Spas most commonly have a 5500 watts 240 volts water heater, controlled by a contactor (high power relay) rated at 40 or 50 amps that would be perfect for switching on your lights. Another style contactor with the expose contacts as seen in this link http://www.hydroponics.net/learn/gro...controller.asp would also work great for your needs. Shouldn't be a problem getting a Double Pole Single Throw (DPST) contactor for $20 or $25 on Ebay. Be careful that you select the contactor with a coil operating voltage that match your timer voltage. Most people like to use a 120 volts timer to switch the relay on and off, and thus would order a contactor with a 120 volts coil and make a trigger cord out of an ordinary 120 volts power cord to connect the timer to the contactor coil terminals. I prefer to have the inline fan (that will be cooling those lights running on that relay) to be powered by the same timer or trigger cord. Timers have been known to fail and I wouldn't want a situation of lights running without a fan cooling them. Glad to see you decided to use two contactors (relays) to divide the lights into two separate group of four.
It is for this reason that contactors are never even loaded to 50% of their rated output.
The preceding message was not a series of opinions rather a logical chain of facts from a Master Electrician.