Power y-cable to cross circuits

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  #1  
Old 01-31-12, 03:17 PM
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Power y-cable to cross circuits

I have a theater lighting dimmer pack that draws right up to the 20AMP capacity on my circuit. I have an additional 20 amp circuit within about 2 feet of the source for the element. Understanding that an electrical item will only draw the power that it needs, i was wondering if it would be possible to make a y-cable that would have one female end going to two male ends. With this I could allow this dimmer pack to draw power from two different 20-amp circuits without overloading either of them.

Would this work or not? Is there any potential hazard to doing this?

Seemingly, it would only draw the amount of energy it needed, but it would just have two potential sources instead of one.

Thanks,
-brent
 
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Old 01-31-12, 03:34 PM
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It will not work and is very dangerous. If one of the male plugs came loose you would have the metal prongs exposed while charged with lethal voltage.

Install a 30 amp circuit using #10 wire and a NEMA 5-30 receptacle. Place a matching cord cap on the device.
 
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Old 01-31-12, 04:38 PM
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Generally in theater/performance areas, Receptacles are on dedicated 20A GFCI protected circuits, or a spider box is used. The circuits are designed to operate at full capacity so don't worry about the high demand of the dimmer pack.
 
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Old 01-31-12, 05:03 PM
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Are you saying that it wouldn't work because of the possibility of dangerous exposure, or it actually won't work in solving the problem. If I were able to insure that the plug wouldn't be removed (especially since it's 20 feet in the air and only accessible with ladder), would the concept be viable?
 
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Old 01-31-12, 05:07 PM
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The dimmer is actually exceeding the capacity of the single circuit. What I'm trying to do is expand the capacity that the dimmer can draw from without having to rewire my circuit panel.
 
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Old 01-31-12, 05:17 PM
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With only a very few exceptions, none of which apply in your situation, paralleling different circuits is forbidden. You need a new, properly sized branch circuit.
 
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Old 01-31-12, 05:29 PM
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Ok... I think I get the picture... out of curiosity, what would be the few exceptions. I promise... I'm no longer planning on doing this, I would just like to learn more. I really appreciate the posts.
 
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Old 01-31-12, 06:19 PM
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Ok... I think I get the picture... out of curiosity, what would be the few exceptions. I promise... I'm no longer planning on doing this, I would just like to learn more. I really appreciate the posts.

Wires larger than 1/0 and CAM-LOCK cables.
 
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Old 01-31-12, 10:26 PM
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Justin, I don't know what a CAM-LOCK cable is but even when you are allowed to use parallel conductors you cannot install them on paralleled overcurrent protective devices.

Quite honestly, I can't think of ANY time that paralleled circuit protection (fuses or circuit breakers) are allowed. Close would be a "bus tie" between two transformer vaults (private substations) in an industrial situation but that is still not the same as using two branch circuits in parallel.

Aha, remembering my utility days we DID have paralleled circuits from the generating stations (and substations) to the grid but THAT is the only instance I can think of that used paralleled circuits with each circuit having its own protection.
 
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Old 02-01-12, 03:43 PM
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Justin, I don't know what a CAM-LOCK cable is but even when you are allowed to use parallel conductors you cannot install them on paralleled overcurrent protective devices.
It's a high-power single-conductor cable used in theatrical, and yes, it uses only 1 OCPD.

 
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Old 02-01-12, 04:41 PM
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Thanks, Justin, I know exactly what you mean after that picture. However, those are not "cables" but individual conductor connectors. I've seen those connected with short (maybe three to five feet long) conductors to portable circuit breaker panels and then cables to either lights or additional power panels. (I worked in a large entertainment/convention/trade show complex for about four years several decades ago.) As I recall the feeders were from 50 to 100 ampere bus duct circuit breakers located in the utility tunnels and the connectors were located in floor boxes throughout the facility. I always thought they were an accident waiting to happen.
 
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Old 02-02-12, 04:02 AM
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How many lighting fixtures are on this dimmer, and what is the wattage?

Four 500-watt lights will draw 2000 watts, which is 400 watts under the total wattage on a 20-amp, 120-volt circuit. (20 amps x 120 volts = 2400 watts.) It's never a good idea to load a circuit to the full 2400 watts, though.

(In fact, 80 percent, or 1920 watts is the max for continuous use.)

If you need to connect more lights you should add another dimmer pack and another 20-amp circuit.
 
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