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Thread: motor contactor vs lighting contactor

  1. #1

    motor contactor vs lighting contactor

    Can someone describe the differences between these two for me please? The lighting contactor seems to be a lot more expensive than the motor contactor.

  2. #2
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    The motor contactor (starter) will also include provisions for installing the overloads and will have aux contacts

  3. #3
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    The primary difference is in the contact material and its resulting ratings.
    For example:
    A NEMA Size 1 motor starter is continuous rated 27A for motor starting and only 15A for "tungsten lamp loads" (fluorescent lamp loads are treated like motor loads).
    A NEMA Size 1 lighting contactor is rated for 30A fluorescent lighting and 20A for "tungsten lamp loads".

    Another difference is in the design for additional features and accessories. Lighting contactor designs include an option for mechanically held (latching) construction that is not needed in a motor starter.
    Just because you can, doesn't mean you should.

  4. #4
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    This may be obvious, but lighting contactors often have more contacts than motor starters. And lighting contactors can be electrically held (like a motor starter), or mechanically held.

    Steve

  5. #5
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    Gobble, what is your intended load, including poles and current?
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

  6. #6
    11 1500 watt lights on a pole that is prewired for 3 wire 480 volts. Got 16 of those around some athletic fields.

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    In that case, if they're to all be switched together (and presuming they lights have their own panel), you might want a single large contactor to switch the entire panel.
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

  8. #8
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    Quote Originally Posted by LarryFine View Post
    In that case, if they're to all be switched together (and presuming they lights have their own panel), you might want a single large contactor to switch the entire panel.
    My experience is the inrush from a 400A HID lighting panel being switched by a contactor is often enough to trip the 400A feeder breaker. I like to keep my switched ballast circuits to 200A max.
    Just because you can, doesn't mean you should.

  9. #9
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    Quote Originally Posted by jim dungar View Post

    A NEMA Size 1 motor starter is continuous rated 27A for motor starting and only 15A for "tungsten lamp loads" (fluorescent lamp loads are treated like motor loads).
    .
    When you say fluorescent lamps loads are treated like motor loads are you referring to the fact that they strive to produce a constant power output.

    I was looking at a particular 100W light recently and noticed that it had a multi-tapped ballast and that with lower voltage the light drew more current. I would think that a light would act more or less as a resistive element, and therefore a reduced voltage input would create a reduced current draw. Is there something in the ballast that causes the light to produce constant power and thus exhibit this relationship?

  10. #10
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    Quote Originally Posted by mull982 View Post
    When you say fluorescent lamps loads are treated like motor loads are you referring to the fact that they strive to produce a constant power output.

    I was looking at a particular 100W light recently and noticed that it had a multi-tapped ballast and that with lower voltage the light drew more current. I would think that a light would act more or less as a resistive element, and therefore a reduced voltage input would create a reduced current draw. Is there something in the ballast that causes the light to produce constant power and thus exhibit this relationship?
    That's one main function of a ballast for either fluorescent or metal halide lights - keep the power output constant even if the input voltages change. The other main function is starting the lamp.

    If you think about it, its probably very rare (if ever) that you see a fluorescent or MH fixture dim when a condensing unit kicks on.

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