The two types of self-contained emergency lighting are maintained and non-maintained systems. They differ in function, uses and maintenance requirements.
You must either leave maintained emergency lighting illuminated all the time or switch it on and off manually as desired using a regular light switch or similar controller. Non-maintained emergency lighting is switched on and off by an automatic controller and only illuminates in the event of a power failure.
Government fire safety codes require certain non-residential recreational premises to install maintained emergency lighting. This includes theatres, restaurants, public house, concert and exhibition halls, dance clubs and sporting arenas, anywhere the primary lighting may be dimmed and anywhere in which people may consume alcohol. Non-residential recreational premises that don't meet these criteria and any premises with fewer than 250 people present simultaneously can use a non-maintained emergency lighting system instead, if preferred.
Maintained emergency lighting is more expensive to operate and requires more frequent maintenance because it commonly remains illuminated for hours at a time. This uses more electricity than a non-maintained emergency lighting system and necessitates more frequent lamp replacement.