relays/contactors

hi i have just purchased a new 400watt hps light shade and ballist but need to know if i need a contactor or relay with my setup as i have only used cfls in the past pleae let me know if i need one or if its just something the shops recomend for a little more cash..

I might be able to help, but I need a little more information. What voltage is your ballast for one? What voltage do you have available? How are you planning on controlling your light? ie: timer, switch etc.

I just plugged mine in to a timer and off i went What would you want a relay for exactly? I may be wrong mate but i wouldnt think you need one.

i have a 400 watt powerplant ballist.i hant set up yet as dont want to blow anything up lol electrics not my thing..and i want to use a timer.

Well your timer is probably gonna be 110 volt, if your ballast is 120 volt also you can just plug the light into the timer. However if your ballast is 240 volt or higher you should in fact control it with a relay or contactor. You need to also make sure that the amp draw of you ballast is not more than your timer "if 120 volt" or your relay or contactor. The ballast should be marked on the side with all the pertinent info>

thanks seems to be getting technical now lol

It can be but I do the shit for a living so if you need more help let me know. Like smokey said though as long as your light is 120 volt just plug it into your timer and you are good to go.

You can plug it in either way (120V or 240V) if thats what you want to do or it can be hooked up to a switch or it can be hooked to a timer and a contactor. It just depends on how you want it to work.

The relay or contactor is only necessary if the amp load of the circuit is to great for the control. ie. You can't turn on an electric hot water tank with a light switch. The switch is rated for 15 amp and one hot water heater element will pull aprox. 20 amp. If the ballast is 400 watt input it will pull aprox. 3 amps on 120 volt circuit or half that on a 240 volt circuit. Just check your timer. It should say on it what the specs are that it is rated for.

cheers thats made alot of sense will do.

When a HID strikes up it takes a huge surge of power mate. I dont know about American voltages, but in UK we have 240V. A contactor is essential here, many a grower has had the timer contacts fuse without one, and fires have been caused. I use a 400W HID, I burnt out 2 timers before i found out the cause . I use a contactor/relay now and havent had a problem since. If your light stays on after "off" time, or goes off and doesnt come on at the set time, your contacts have most likely fused in the timer. Personally i would never run without one, its one of the most important things you need for safety. As i said thats on our voltage, but even on 110v you still get a surge at strike up. Id post a link to the forum but its prob against the rules. Its essential mate, for us at least.

well thats made its easy so how much do they cost then, i would rather be safe then sorry the wife is moaning now cus ive got to spend more money,weres the bong at !!

Good point smivvie. I have not ever check to see what kind of start up amps one of these lights pulls. Most electric motors and such do pull higher amps on start up.

bud master said:

well thats made its easy so how much do they cost then, i would rather be safe then sorry the wife is moaning now cus ive got to spend more money,weres the bong at !!

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I cant say how much they are if you are in USA mate, Here i paid £30 for one that can run 1 1000w light, or 2 400w to 600w. I wouldnt buy a cheap chinese one though, do a google search for HID contactors, and personally i would only buy new, and from a shop. You cant really put a price on safety when its electrical. HID was never designed for inside use, its charges and discharges in the ballast require extra protection, better safe than sorry.

UK growers MUST use a horticultural lighting contactor such as these

http://www.growell.co.uk/p/0850/Eco-Technics-Light-Switching-Timer-Contactors.html


or something like this.


http://cgi.ebay.co.uk/CONTACTOR-TIMER-22amp-HPS-CFLS-GROWLIGHTS-/230578950840?pt=UK_HomeGarden_Garden_PlantsSeedsBulbs_JN&hash=item35af9392b8


I use both. ECO technics for my flower room and the contactor timer for mother/clone area.



J