[PW] ?How is a 277 Volt Lighting System Wired in Series to Turn On a Large Group of Fluorescent Light Fixtures Wired in Series?

brian whatcott betwys1 at sbcglobal.net
Wed Sep 30 16:39:15 PDT 2015


A Four wire wye three phase system is standard for commercial and 
industrial facilities.
This offers 480 volts phase to phase, and 277 volts phase to neutral.

Fluorescent lights running at 277 volts are wired in parallel between 
one  phase wire
  to neutral, but several circuits may be provided using different phase 
wires  in order
to share the load equitably.

This is just the same wiring scheme you would use to light your home: 
one phase
to neutral offering 120 volts, switched individually or in multiple 
parallel-wired  lights
  per switch.

The higher voltage used commercially offers greater power transmission 
for a
given gauge wire, which offers installation cost savings.

People who handle three phase systems of this type need to be aware of 
the relevant
wiring standards provided in National Electrical Code - see NEC 210-6(c) 
and 225-7(c).

A person who believes he can wire 277 volt lighting fixtures in series 
is not suited to safely
wiring equipment at these voltages and is encouraged to use an 
industrial electrician.

Brian Whatcott

On 9/30/2015 2:29 PM, Sam Shipley wrote:
> I have a rather lengthy technical electronics question to submit for a patron.  Please see below:
>
>       "How is a 277 volt lighting system wired in series to turn on a large group of fluorescent light fixtures wired in series?  One switch turns on around 50 fixtures at once.   I want to understand this from the breaker to the last fixture.
>       When changing out the ballast in a fixture, there are some wires that are not needed, that the electrician has removed and capped.  This process is similar to a 120 volt system, but has more wires in the 277 volt system that (I think) remain hot.
>        I have tried to find the information by searching the internet, using the keywords Fulham Ballast Co. Inc.   I also search the "How Things Work" web site."
>
>
> Thanks for any help you can provide.
>
> Sam Shipley
> Reference Librarian
> Dodge City Public Library
> Dodge City, Kansas
> sams at dcpl.info<mailto:sams at dcpl.info>
> (620) 225-0248, x201
>
>
>
>
>
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