You can expect to find a so-called fireman's switch in most large buildings that consume a lot of power. Usually tucked away in an isolated but accessible area, the switch is rarely used but can come in handy when the situation calls for it. That's because the fireman's switch provides an easy, safe way to cut power from a building quickly.
Generally, a fireman's switch allows for quick access to a power control for a building or section of a building. Why would a person want to be able to quickly shut down the power to a part of a building? Consider the name -- a fireman's switch is commonly employed in times when there is a dangerous situation -- like a fire -- and power must be cut from the building very quickly but in a safe and direct fashion that precludes immediate access to the dangerous area.
A fireman's switch exists to cut the power quickly, but the switch is only useful if it can be easily reached during a time of disaster. A common location for such a switch is in a building's stairwell. Such a location can be easily reached in a short amount of time but is relatively isolated from the power sources that could be causing problems.
A fireman's switch cuts the power, but exactly what power it cuts can vary depending on the building. Some fireman's switches, when activated, will cut power to an entire building immediately. However, in larger buildings, or those with multiple purposes, multiple switches could be installed. Each switch would be assigned to a specific area of the building, allowing for more precise power control. Alternatively, a single fireman's switch could be installed, but with settings that allow for the power to be cut only to the necessary areas.
Though frequently found in buildings, a fireman's switch is also a common feature in swimming pools. Specifically, the device is used in pools that have heaters. A pool switch cuts power to the heater after a designated period to ensure the heater is not left on indefinitely, as it can be a fire hazard.