Dangers of 277 V

[tom baker]

Had an report of non-electricans replacing 277 V ballasts in a building.
Any links to data showing the dangers of 277 V over 120 V would be appreciated.

 

[mcclary's electrical]

Had an report of non-electricans replacing 277 V ballasts in a building.
Any links to data showing the dangers of 277 V over 120 V would be appreciated.

One of the big electrical contrators had a twenty year old killed a few years ago, working on 277 volt lights while they were hot. He was in a tight place in a ceiling with his head against a metal duct, he was hot and sweaty. His hand hit 277 and went out his head.

 

[don_resqcapt19]

Tom,
They are both dangerous and working either one while energized is an OSHA violation. That being said, given the same person, methods, tools and points of connection, there will be 2.3 times more current flowing through the person if he gets shocked by 277 as compared to 120.

 

[SEO]

277V produces aprox 5 times the wattage of 120V with the same resistance. Watts = E sq/R . So if a person has a body resistance of 500 ohms and has 120V applied his body have 28.8 watts of cooking. Using the same calculations with 277V appied his body would have aprox 153.5 watts of cooking.

 

[wireddd]

Whether they were union or not has no bearing. I've seen plenty of union people not take the necessary safety precautions before working on live equipment.
We have several customers who do thier own 277 volt ballast, some live circuits, some dead.