IS this relay ok to use for lighting

Discussion in 'General Electronics Chat' started by Iron, Mar 31, 2015.

  1. Iron

    Thread Starter New Member

    Mar 31, 2015
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    I have a aquaponic and a hydroponic grow room I am building for my wife.
    I have a 240v, 1000w HID lamp and a inductive ballast.
    I originally bought cheap timers. I realized that I just happen to have these A-B type N, 120v AC relays.
    CAT. No: 700-N400A1
    I would like to use my cheap timer as a control circuit for this relay. Is this OK?
    Please forgive me for this next question but with power constantly applied to the coil to keep it closed, how much power will that consume over 18 hours? Our remaining budget for this project is almost gone. My thought is that in the future I could purchase the A-B off delay timer for this, if it changes it from electrically held to mechanically held. This is a gray area for me. If anyone could elaborate, I would be so thankful.
    -Mike
     
  2. Iron

    Thread Starter New Member

    Mar 31, 2015
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    ***correction: 240v/1000w ballast.
    Not lamp.
     
  3. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    Typical relays use about 1-3W to keep the coil energized. You do the math.
    Since the timer current is only 1000W/240V ~= 4A. What is the contact rating of the cheap timer?
     
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  4. Iron

    Thread Starter New Member

    Mar 31, 2015
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    The ballast can be 120v or 240v. At the last minute I opted to pull new wire so that I could wire 240v. This is after I heard that these plug in timers commonly sold in hydroponic stores often fail, because they can't handle the inrush current from starting the HID lamp. I am assuming that it will run a little smoother and cooler as well. Therefore prolonging the life of the ballast.
    Thank you very much for your help. Here is the only info given on the plug in timer:
    maximum Amperage 15
    maximum wattage 1875
    Voltage 125
     
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
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    These are basically control relays, used typically used in industrial logic systems before the popular PLC replaced them
    I would tend to pick up a Contactor which are motor rated.
    These can be had relatively cheap on ebay, Telemecanique etc.
    Usually the coil current is insignificant.
    Max.
     
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  6. MikeML

    AAC Fanatic!

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    The whole reason that your lights have a ballast is to limit the inrush current when starting. You could look up the peak inrush current for your loads. With a 15A current rating on your timers, I wouldn't worry about a relay.

    If the purpose of the relay is so you can use a 120V timer to control a 240V load, then you must use one...
     
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  7. Iron

    Thread Starter New Member

    Mar 31, 2015
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    Mike thanks for that. I never actually had a thought about what a ballast is actually for. Very cool. I may even do some reading about it tonight, if I can find anything online.
    Max, do you know what the rating of this relay? I am surprised that it is nowhere on the box and not in the paperwork either. I bought two of them brand new a few years back at a garage sale for 50 cents. Our budget for this project has dwindled quite a bit. If it is safe to use one, I would like to. I would prefer to run her light at 240v. I have a very nice 12x12, deep, Hoffman, electrical box to mount it in. Something else I picked up a few years back.
     
    Last edited: Mar 31, 2015
  8. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    Found this
    CONTACT VOLTAGE 120/240/300 VAC AT 50/60 HZ; CONTACT CURRENT 10 AMPERE AT 120/240/300 VAC;
     
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  9. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Yes I meant to mention 10amp rating, they were $500.00 ea back then, AB has never been cheap!
    Max.
     
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  10. Iron

    Thread Starter New Member

    Mar 31, 2015
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    I apologize, but just to be clear that I understand and that there are no unforseen issues that I am not aware of, The 1000 watt ballast wired at 240 volts will put the current at 4.16667 amps, which is about 42% of the relay's rated amperage. So we agree that this should be OK to use?
     
    Last edited: Mar 31, 2015
  11. MaxHeadRoom

    Expert

    Jul 18, 2013
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    But these relays were intended primarily for logic design, (control relays) which usually was for small loads as other relays or solenoids etc, they may not stand up to high inductance loads or inrush switching.
    In the '70's & '80's I scrapped cabinets full of these when redesigning automation systems for PLC control.
    You could always try them, and if they don't stand up, replace with higher rated contactors.
    Max.
     
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