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Thread: Lighting Contactor

  1. #1
    Join Date
    Apr 2014
    Huntsville, Alabama

    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
    San Francisco Bay Area, CA, USA
    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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