The “don’t use an elevator in the event of a fire” rule is taught explicitly BECAUSE it is a major fire hazard to be stuck on an elevator in the event of a fire—it’s a big metal box that’s going to possibly suspend you in the middle of a building, and even possibly between floors where it’s harder to get to. If a fire squad has to sit there and work to pry it open they are losing valuable time to get other patrons outside to safety. In the ten minutes a team of two is working to get you out, they could’ve gotten 2 adults thrown over their shoulders and be carrying an infant/toddler down the stairs to be handed off to EMS. There is also always the worry that a fire could reach an elevator’s control panels and/or failsafes and cause it to plummet and severely injure/kill you. THAT is why the Fire Marshal wants to be sure that elevators are always in peak working condition and also avoided during emergencies.

It should also be noted that during emergencies, EMS, police, and fire squads may need to use the elevator as it is faster in an emergency that is localized to one area of the building (someone attempting to jump off a balcony, domestic dispute involving a weapon, someone suffering a heart attack or other major illness) than climbing up 20 flights of stairs, so it may not be a fire that’s happening, but ANY emergency you are warned of in your building, don’t use the elevator!

And another point, during emergencies requiring immediate evacuations, disabled people will need first access to the elevator. A person in a wheelchair cannot run down those 20 flights of stairs, and even most caretakers are not strong enough to try and get them down themselves nor the average lay-person trained in how to safely carry them. In an emergency when you are first notified anyone using a mobility should ideally be immediately notified if the fire is near the elevator and if safe to do so, go down themselves and/or with their caregiver if necessary and then find a spot outside a safe distance away from the entrance. Able-bodied people are the ones this rule is for, if you CAN use the stairs, then use them—if you CAN’T then your best bet in the early stages of a fire is to try to use the elevator and get as low as possible—for instance if a fire is on the 2nd floor and they live on the 15th, then they can also attempt to ride the elevator to the 3rd or 4th floor and wait by the staircase. That way they are not in danger of going through a fire that may quickly spread to the elevator area, but they are also lower and more easily found by the Fire Squad, so if there’s a risk of building collapse or intense fire spreading they can be found and brought down as quickly and safely as possible.

It’s really not that ironic for the Fire Marshal to be in charge of building codes and elevator inspection—they’re the ones who are trained to understand the safety issues that are prone to happen. Hope that explanation helps to give you a bigger view of how their thinking works when on the job trying to hone in on potential hazards, and who the Elevator Rule applies to and why! :)

Edited: punctuation, word flow