Strange Voltage Outlets / 347 volts ?????

Aug 05, 2006 8 Replies

I was just looking up some oddball outlet I got in a pail of electrical stuff at an auction. I went to this website.

formatting link
What I have is the # 24-15R Listed for 347V AC.



Now I know what it is, but where do they use 347V AC ? Or, for that matter, where do they use 277V AC which is also listed?


120 240 208 480 are all common, but these 277 and 347 I never heard of.

By the way, this is a very handy website. Bookmark it !!!!



Mark


277 volt is common for lights in some commercial buildings.

If you have a 480 volt 3 phase circuit connected in the Y configuration, the center of the Y (which is often grounded and also the neutral) to one of the ends will be 277 volts. This is often used for lighting in buildings that have 480 volt 3 phase power. The 347 volts is the same way for a 600 volt Y connected circuit.

277 is the phase to neutral voltage of a 3 phase 480 volt system. Very commonly used for the lighting in commercial buildings. 347 is the phase to neutral voltage of a 3 phase 600 volt system.

Phase to neutral voltages can be calculated by dividing the phase to phase voltage by the square root of 3.

John

JohnR66 wrote: > 277 is the phase to neutral voltage of a 3 phase 480 volt system. Very

Indeed. Fluorescent lamp ballasts and even otherwise ordinary looking medium base (like standard household bulbs) incandescent bulbs can be had in 277V versions.

Could you please post the mathematical formula. I'm pretty math challenged, but a sample might help. The square root is the part where I get lost....

The square root of 3 is about 1.73. To get the voltage of a 3 phase system in the Y connection you devide 480 by 1.73 and get about 277. The same with the 600 volt circuit to get 347. The numbers are not exect, but just the nominal values.

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required