View Full Version : Help with 277 Volt Emergency Lighting or Flourescent Fixture Wiring

September 13th, 2005, 05:03 AM
I need some knowledge of 277 volt wiring for emergency lights and flourescent light fixtures. Does 277 volt mean they are 3 phase systems? Can anyone give me a simple explanation and wiring diagram of how such fixtures would be wired to their power source

September 13th, 2005, 10:07 AM
This must be a commercial and or industrial setting otherwise you most
likely wouldnt have 277V fixtures.

Yes, it would be probably be a 480/277V 3 Phase type of service.

One leg to neutral would be 277v and between phases would be 480V.

277V fixtures are common in large stores and Industry.

If the Ballasts are rated for 277V they should be marked for that voltage.

They are physical similar to 120Volts ones also.

Also, on the Emergency lighting. The person laying out the lighting will
select maybe every 5 or 6th fixture as a emergency light. (just an example).
Somtimes they will have a Battery backup or a relay for a Second source
of power (eg. Generator). Usually there is a wiring diagram with or on
the fixtures.

Be carefull with 277V!


September 13th, 2005, 01:13 PM
Thanks for your help. You cleared up what I thought. I rarely have the occasion to work with three phase and just needed a little calarification. Yes it is a commercial building.

January 25th, 2013, 05:42 PM
Does that mean that 277 volt to ground and their is no neutral? Do the fixtures get tied to ground as well?

February 3rd, 2013, 02:26 PM
Yes it is 277V to ground and you must have a neutral in this circuit (it is 277V hot to neutral, 480V hot to hot). A ground wire is required too. This circuit will have a hot wire (generally yellow, orange, or brown but doesn't have to be one of those depending on your site color coding), a neutral wire (white or grey), and a grounding wire (green or bare).