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Thread: Bay Lighting

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    Bay Lighting

    First post! Hope this makes sense!

    So here is what we got going on. Owner of the shop we are wiring/remodeling want to turn 4 bays of lights on. From 2 different locations,3-way. Existing wiring has 3 switch legs in 4sq for 3 bays, feed by 2 circuits. Tied all lights together and they draw 17 amps. Is it possible to tie all lights together switched from 2 locations on 2 separate circuits?

    Thanks guys!

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    Yes it is possible. The best way is to control the lights with a contactor and use the three way wiring to control the coil.
    If you don't think too good, don't think too much.

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    I figured as much. A 2 pole contactor 120v coil but wiring it is what I’m getting hung up on.

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    It's just a 3 way switch with the coil on the contactor taking the place of the light bulb.
    If you don't think too good, don't think too much.

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    Wire the coil as a load to a pair of 3-ways as you would for any light.

    For your two circuits, use a 2-pole contactor. Wire each hot wire to a line terminal and each lighting group to the corresponding load terminal, as if each contact pair was a single-pole switch.

    Neutrals wired together as usual.
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

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    By using 3 way wiring you can do that.

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    190611-0814 EDT

    I would use GE RR relays, and low voltage control. Now you can do all sorts of things. But most electricians seem to get totally confused by such systems.

    .

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    Quote Originally Posted by gar View Post
    190611-0814 EDT

    I would use GE RR relays, and low voltage control. Now you can do all sorts of things. But most electricians seem to get totally confused by such systems.

    .
    Those are indeed cool systems we service a number of retail places that originally had them, but a bit of a headache to get a simple time clock or occupancy sensor hooked in to one of those pulse controlled relays. I do like that they are actual latching contactors which are the next best thing to solid state.
    Comments based on 2017 NEC unless otherwise noted.

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    190613-1430 EDT

    tortuga:

    I favor the RR over a solid-state for a couple reasons.

    One, voltage drop in the millivolts compared to more than a 1 volt. That is a big difference in switch power dissipation.

    Two, the RR is much less likely to fail under high transient voltage conditions than a solid-state unit.

    Three, high ambient air temperature is less of a problem for the RR, than a solid-state.

    If a time clock has separate NC and NO contacts, or a DPDT, but not a single SPDT output, then it is simple to pulse drive an RR. Requires a simple DC supply (a diode and transformer) to two RC filters with the filter capacitors separately connected to the NO and NC contacts. Each capacitor is made large enough to guarantee triggering of the RR (by memory possibly 500 to 1000 mfd), and the resistor made large to minimize power waste, but small enough to overcome capacitor leakage (possibly 10,000 to 100,000 ohms), and to recharge the capacitor in a reasonable time.

    .

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