Quite interesting to note that the Fire Safety plan for the CN Tower is vastly different then any other building in North America. If your up in the tower and the fire alarm rings, you basically proceed to the Glass Floor level (Level 2) and await for the inhouse security guards (Known as CN Tower "Protective Services") to investigate the alarm. The new fire system is very advanced and can locate the source of the alarm to exactly where it was triggered. Elevators 1 and 2 (the service elevators) will proceed to the Security level automatically, and Elevators 3, 4, 7, and 8 will proceed to level 2 up at the top (the glass floor level). Elevators 1 and 2 are for emergency personel, and The rest are for evacuation.
If there is a real emergency the 2nd stage alarm will be activated and evacuation of the upper levels will commence via the elevators if its deemed safe enough to evacuate to the lower levels. If however the fire is in the lower level and is too close to the elevators, they will hold the elevators up at level 2, and move everyone outside to the outdoor section. Its safer up there, then coming down into a fire. People in the skypod (the highest observation level) must evacuate that level via the stairs, to level 2. Since those elevators (5 and 6) are inside the building, and not external to the structure, it is not safe to evacuate people by them. No one is to evacuate the tower via the main staircase to ground - that is deemed too unsafe.
The staircase, which used to be on the outside... specifically on the north side of the tower. Was rebuilt inside the tower in 1989, and the external staircase was replaced by 2 new elevators.
2 Water pumps work in tandem, pumping water up to tanks located in the staircase between the skypod and the main pod levels. one is for freshwater, and one is for fire water. if the fire water tank runs out, it will draw from the fresh water tank. The fire tank is huge, something like 200,000 gallons..
If the elevators loose their main drive or power for some reason, they can still come down, but it will take them about 15 minutes to get from the top to the bottom. because they will travel at the speed of one of those small slow elevators, such as you would find at a doctors office.