NEC 225.7(C) - Exterior Lighting

[clausb]

20+ years of experience and this industry is still a constant learning experience! As an electrical engineer involved in the industrial sector I was taken aback by the article in the July 2007 EC&M about 277V exterior lighting fixtures not being allowed within 3' of windows, platforms, fire escapes, etc. Our designs typically incorporate 277V lighting and small exterior wall luminaires 24" from the edge of the exterior man doors, between dock doors and recessed in canopies above dock doors. Our directions on drawings have been violating code, the installing contractors have not picked up on the violation nor have any inspectors!

Looking back at older code books, this piece of code is definitely not new. A simple item in the code, overlooked. We have to remember we can never think that we are above performing simple code review and rereading and studying the code we think we already know.

 

[iwire]

the installing contractors have not picked up on the violation

I know I have installed fixtures in those locations per the drawings and never gave it a second thought.

Thanks for the post, I learned something new.

 

[charlie b]

I may be in the process of learning something new, but I am not there yet. That article does not mention doors. Is the installation you described in violation, if the light is 2 feet from a door? :-? :-?

Reading the text literally, I would say no. I do not consider a door to be included in the phrase "and the like," given that the other items on the list are nothing at all like doors.

But what I do not understand still is the intent of that article. What is the hazzard of having a 277 volt light within 3 feet of a window? Why is that hazzard not also present if the light is within 3 feet of a door.

I echo Bob's thanks for pointing this out. Now perhaps someone has some more information or answers to offer?

 

[dicklaxt]

I think it probably was derived from 110.26 ,working clearance.

dick

 

[don_resqcapt19]

What is the purpose of this rule? We can install 277 volt lighting inside in an 8' ceiling, but not outside within 3' of a window? Why is it less safe outside? How does the supply voltage change the safety of the installed fixture?
Don

 

[charlie b]

How about this for a guess: They wish to discourage people from attempting to lean out the window to replace the bulb. If the fixture is 3 feet away, a person could not reach, and would have to use a more controlled and safe method of replacing the bulb. A door would be different because a person attempting to replace the bulb starts out with a normal floor from which to construct a method of access (e.g., ladder or scaffold).

 

[raider1]

Charlie,

Wouldn't the landing at the exterior side of a door be a "platform"?

I do understand that the light would be more than 3' above the landing or "platform".

Chris

 

[don_resqcapt19]

Charlie,

They wish to discourage people from attempting to lean out the window to replace the bulb.

Unless the lamp is an incandescent lamp, I don't under stand how the supply voltage would make any difference.
Don

 

[Dennis Alwon]

I am not sure why the voltage would make a difference but in reading 225.7(C) I was wondering if it had something to do with fire trucks and ladders etc. Again why would 110 volt fixtures be allowed?

 

[benaround]

225.7(C) allows 277vac fixtures outside, just not less than 3' from windows etc.