Emergency Egress Lighting for Roofs?

[rr]

I'm working on a 3-story police facility. We have multiple HVAC units mounted on the roof with two stairway exits leading to lower floors. The CM has mentioned that we need emergency egress lighting for the roof area. I can understand two small wallpacks adjacent to the stairway doors. But I'm at a loss as to how and why I would need to provide illumination on a roof for egress to the stairs in order to meet NFPA 101 or the UBC. I've never heard of this.

Any ideas?

 

[dahualin]

I don't think the roof area needs emergency lighting. Emergency lighting is mainly used for lighting egress path defined by building code. Normally nobody is going to roof at night.

 

[broadgage]

Here in the UK I have been told that the need, or not, for emergency lighting on a roof depends on whether or not normal (non emergency) electric lighting is installed on the roof.
If normal lighting is installed, then emergency lighting is also required.
The reasoning being that if the roof is lit, persons would reasonably be expected to go onto the roof at night, perhaps to service A/C equipment. Any failure of the power supply could expose such persons to risk, hence the need for emergency lighting.

If however the roof is not equiped with normal lighting, then in general emergency lighting is not required.
The reasoning being that the absence of normal lighting means that persons are unlikely to be on the roof at night.
If someone WAS on the roof at night they should be equiped with a flashlight or lantern, since the area would be dark normally.