# Is there such a thing as 3 phase lighting?



## guitarboyled (Jun 22, 2009)

More than one phase per bulb or tube... is that possible?


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## Big John (May 23, 2010)

Sort of. You can connect a lamp between two phases and feed it with 208 or 240 or 480. There are incandescent lamps built for those voltages, but they're rare. It's very common to feed fluorescent ballasts that way.

You could also take three phases and feed three equally sized lamps if you connected the screw shells together in a Y and they would operate without a neutral.

You cannot however, connect 3 phases directly to a single lamp.

-John


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## McClary’s Electrical (Feb 21, 2009)

Big John said:


> Sort of. You can connect a lamp between two phases and feed it with 208 or 240 or 480. There are incandescent lamps built for those voltages, but they're rare. It's very common to feed fluorescent ballasts that way.
> 
> You could also take three phases and feed three equally sized lamps if you connected the screw shells together in a Y and they would operate without a neutral.
> 
> ...


The nec does not allow energizing a lamp shell holder. The cec does, however


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## 220/221 (Sep 25, 2007)

guitarboyled said:


> More than one phase per bulb or tube... is that possible?


Trick question?

More than one *leg*, sure.

*Three phase* circuit. AB feeds some lights, BC feeds some and CA feeds some.

But, you won't find a ballast or lamp that uses all 3 phases.


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## RePhase277 (Feb 5, 2008)

mcclary's electrical said:


> *The nec does not allow energizing a lamp shell holder.* The cec does, however


There is no rule against energizing the shell of a lampholder.


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## wildleg (Apr 12, 2009)

as indicated above, when people talk about 3 phase lighting, they are generally talking about lighting that is fed from 3 phase power sources, but the ballasts are actually wired single phase, whether there is a neutral involved or not. Feeding a circuit with 2 phases of three phase power is still considered single phase, by most. It is just semantics though. In other words, if a multitap ballast had 208,240,277,480 taps, as long as you fed it with the correct voltage and frequency and amperage it would work, whether it came from a single phase, split phase, or three phase power source.


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## tkb (Jan 21, 2009)

mcclary's electrical said:


> The nec does not allow energizing a lamp shell holder. The cec does, however





InPhase277 said:


> There is no rule against energizing the shell of a lampholder.


The closest you are going to get is 410.50 and 410.90.

*410.50 Polarization of Luminaires*
Luminaires shall be wired so that the screw shells of lampholders
are connected to the same luminaire or circuit conductor
or terminal. The grounded conductor, where
connected to a screw shell lampholder, shall be connected to the screw shell.​


*410.90 Screw Shell Type*
Lampholders of the screw shell type shall be installed for
use as lampholders only. Where supplied by a circuit having
a grounded conductor, the grounded conductor shall be connected to the screw shell.​


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## RePhase277 (Feb 5, 2008)

tkb said:


> The closest you are going to get is 410.50 and 410.90.
> 
> *410.50 Polarization of Luminaires*
> Luminaires shall be wired so that the screw shells of lampholders
> ...


Right. Only in a circuit where there is a grounded conductor AKA Neutral. A 208 or 240 V circuit could supply a screw shell type lampholder, and the screw shell will be energized. I have seen this setup in older remote locations where equipment is supplied with only 240 V. Lamps with medium base screw shells rated at 240 V are not hard to come by.


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## electriciansandy (Nov 17, 2011)

mcclary's electrical said:


> The nec does not allow energizing a lamp shell holder. The cec does, however


Those crazy Canadians


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## micromind (Aug 11, 2007)

A single phase load (such as a lamp) can indeed be energized by all 3 phases of a 3 phase circuit.

If the 3 Phase source is a 4 wire delta connection, and the load is placed between the neutral and the high leg, all 3 phases will contribute to the load. 

Also, in a closed delta, all 3 phases will contribute to a single phase load, but two of them will contribute considerably more than the other one.


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## frenchelectrican (Mar 15, 2007)

Big John said:


> Sort of.
> You cannot however, connect 3 phases directly to a single lamp.
> 
> -John


Ya close but some of the very large arc lamp which they run on DC supply do use triphase input to rectifiers to converted to DC voltage to run the arc lamp. 

This typically found in some of very large spotlight lumiaires.
A hint.,, do any you old school guys recall mercury arc rectifiers ?? 

Merci,
Marc


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## HARRY304E (Sep 15, 2010)

frenchelectrican said:


> Ya close but some of the very large arc lamp which they run on DC supply do use triphase input to rectifiers to converted to DC voltage to run the arc lamp.
> 
> This typically found in some of very large spotlight lumiaires.
> A hint.,, do any you old school guys recall mercury arc rectifiers ??
> ...



Lets say you have a three phase ballast .

Wouldn't that ballast supply single phase power to the screw shell.?


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## frenchelectrican (Mar 15, 2007)

HARRY304E said:


> Lets say you have a three phase ballast .
> 
> Wouldn't that ballast supply single phase power to the screw shell.?


Ouias ( yeah ) .,,, but you have to make a pick which triphase ballast input you have to use ( if have tri core set up* ) then single phase output to the screw shell.

Merci,
Marc 


* Not the single core type that will not work


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## dmxtothemax (Jun 15, 2010)

The lighting system in my church is feed off three phase power,
50 amps a phase at 240v (AUSTRALIA).
So its sorta a three phase light !


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## kaboler (Dec 1, 2010)

CEC

30-600 Connections to lampholders

The identified conductor, if present, shall be connected to the lampholder screwshell.

(we call a neutral that carries the returning load an "identified conductor" in canada)


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## BBQ (Nov 16, 2010)

kaboler said:


> (we call a neutral that carries the returning load an "identified conductor" in canada)


I had no idea you guys use DC.


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## brian john (Mar 11, 2007)

kaboler said:


> CEC
> 
> 30-600 Connections to lampholders
> 
> ...


If Present


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## RePhase277 (Feb 5, 2008)

brian john said:


> If Present


That was my point. The NEC says the same. That is another one of the often misunderstood Codes: "All lamp shells have to be connected to a neutral":no:


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