Emergency Illumination 700.16

[retire09]

Exterior landings at exits are required to have emergency exit illumination when two or more exits are required.
It is very common to see this done with a single head emergency fixture outside over the door powered by the exit sign battery inside.
My question is:
Can this be done with one single head fixture?
Do these single head fixtures have two lamps in them?

700.16
Emergency lighting systems shall be designed and installed so that the failure of any individual lighting element, such as the burning out of a lamp, cannot leave in total darkness any space that requires emergency illumination.

 

[steve66]

I haven't seen a single head fixture with two lamps.

I have seen inspectors require two lamps.

 

[hmspe]

I always spec two lamps or more per door, but I can see that an argument could be made based on the terms used. What is the "space" being lit? Is it the egress path at a particular door or is it "outdoors"? What is "total darkness"? I've been on a cave tour where they turned out the lights. If that is what total darkness is then outdoors is never totally dark, even with a new moon and heavy cloud cover. Probably a good Code section to propose clearer wording for.