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Thread: Lighting Contactor

  1. #1
    Join Date
    Apr 2014
    Location
    Huntsville, Alabama
    Posts
    29

    Lighting Contactor

    I have been under the impression that a 3 phase lighting contactor is essentially the same as a motor starter without the overload block. If this is the case, can a 3 phase lighting contactor be used to turn a resistive heater power supply on and off?

  2. #2
    Join Date
    Jul 2006
    Location
    San Francisco Bay Area, CA, USA
    Posts
    7,167
    Resistive, yes.

    Contactor ratings have everything to do with the nature of the load connected to them. At a very basic basic level, the easiest rating to attain is a resistive load rating; the power factor is 1.0 at the moment the load is switches, no induction, no additional sustaining of the arc. As a load becomes more capacitive or inductive, the harder it becomes for the contacts to survive and the lower the "rating" of the contacts. So you will see for example that a NEMA size 1 motor starter can switch a 10HP 460V motor which is 14A FLC, but if the same contactor labeled as a "lighting contactor" is capable of 30A resistive or ballast load.
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