which relay is best for my application?

Thread Starter


Joined Mar 31, 2015
I am just about ready to finish up my wife's aquaponic/hydroponic grow room, but I decided to wire her 1000 watt HID ballast at 240v. The multifunction, self contained, controller I bought, only has a 120v. receptacle. What is the best piece to use to relay the 120v to 240v. Without humming or chattering hopefully. I would greatly appreciate this help. Thank you for your consideration regarding this matter.


Joined Aug 1, 2013
Solid state relays are quiet and very reliable, but some ballasts don't like being driven by a triac. The safest thing is a DPDT relay with a 110VAC coil and contacts rated for your load. Industrial relays and contactors made for control panels have convenient mounting holes and screw terminals. Smaller control relays cost less but have terminals for soldering or special relay sockets. Depends what's available in whatever country you are in, what the controller make and model are, and anything else you didn't tell us.



Joined Jan 15, 2015
Omron MK2P-I with 120 VAC 60Hz coil. This is a DPDT relay to switch both sides of your 240 VAC. The contacts will handle 250 VAC 10 amp resistive load and 7 amps inductive load. Omron is merely a suggestion as a dozen companies or more manufacture these type octal base plug in relays. McMaster Carr Industrial Supply also sells the relays and 8 pin sockets. Use the 120 VAC from what you have to turn the relay On and Off and use the relay contacts to switch your 220/240 volt load.