The Building and Life Safety Codes specify where exit signs and emergency lighting must be installed, how much illumination is needed, how long emergency luminaires must stay on after an outage, and how they must perform. The NEC^® provides the rules on how emergency lighting must be configured.

Not all occupancy types are required by the building codes to have emergency lighting or lighting supplied from an emergency system.

The Building and Life Safety Codes dictate when an emergency system is required to be installed. These rules are based on occupancy type, number or required exits based on occupant load, and common path of egress travel distance to the exit discharge. The larger and more complex a building is, the harder it is to make it to the exit discharge and then to a public way during an emergency.

A good rule of thumb is to remember that any time the occupant load is more than 49 and more than one exit is required, emergency lighting is also required.

IBC Table 1006.2.1 requires two or more exits when the occupant load is 50 or more in occupancy groups A (assembly), E (educational), M (mercantile), B (business), and U (utility). In any of these occupancy groups, as long as the occupant load is not over 49, no emergency lighting or exit signs are required, unless of course the maximum common path of egress travel distance to an exit (shown in the table) is exceeded.

A small business space (Group B occupancy) with a tiny occupant load, such as an insurance company in a strip mall, with a single entrance/exit, is not required by the IBC to have emergency lighting or exit signs since those that enter will easily be able to find their way out in an emergency. Alternatively, a large assembly occupancy (Group A) such as a theatre or night club will be required by the IBC to have multiple exits leading to a public way. Because of the complexity of the many exit paths, emergency lighting and directional exit signs are required to ensure occupants can easily find their way to the exit discharge when the power goes out.

On new projects, always be sure to check all pages of the plans, even if they do not seem to be related to the electrical installation. The first few pages at the beginning of a plan set will tell the occupancy group, occupant load, and number of required exits. If more than one exit is required or provided, then it is likely that emergency lighting is also required by the IBC or NFPA 101.