Emergency lighting design

Emergency lighting keeps exit routes visible when the normal lighting fails, long enough for everyone to get out and for responders to work. A good design follows the actual path people take to the exits, places light where it matters most (doors, stairs, changes of direction), chooses a reliable power source, and is built so it can be tested easily for the life of the building.

What the codes require, in principle

In Canada, the National Building Code and the provincial building codes based on it say where emergency lighting is required, how much light it must provide and for how long. Typical locations include exits and exit stairs, corridors and principal routes to exits in open floor areas, and other spaces depending on occupancy and size. The code sets a minimum illumination level along the route and a minimum duration, which is longer for high buildings and some occupancies. Exit signs have their own requirements for location, visibility and appearance, including the green pictogram style now used across Canada.

The Canadian Electrical Code, as adopted in each province, covers how emergency systems, unit equipment and exit signs are wired and supplied. Equipment is certified to CSA standards, such as CSA C22.2 No. 141 for emergency lighting unit equipment, and generators supplying emergency loads are installed to CSA C282. The National Fire Code and provincial fire codes then set inspection and testing. Exact requirements depend on the edition adopted where you are, so confirm them for each project.

Start with the exit route

Emergency lighting design starts by drawing the route people will take from every occupied area to an exit and then to a safe place outside. The lighting follows that route, rather than being spread evenly across the floor.

Within the route, some places matter more than others. Put light at every exit door, at each change of direction and intersection, at every flight of stairs and each landing, at changes in floor level, and outside each exit door where the route continues. Many designers also light fire alarm pull stations, fire extinguishers and first aid stations so they can be found in a blackout. Exit signs go where the code requires them and wherever the direction to the exit is not obvious, with directional arrows where the route turns.

How emergency lighting is powered

There are three common ways to supply emergency lighting. Many buildings use a mix of them.

Unit equipment

Self-contained battery units, often with two lamp heads, are the most common choice in small and mid-sized buildings. They are simple and inexpensive to install. Each unit is commonly connected so that it senses failure of the normal lighting circuit serving its area, so a tripped breaker in one area brings on that area's emergency lighting, not just a building-wide outage. The drawback is that every unit has its own battery to test and replace, and remote heads fed from a unit over long runs suffer voltage drop, which dims them. Check run lengths and wire sizes against the manufacturer's tables, and see conductor sizing and voltage drop.

Central battery and inverter

A central system feeds many normal-looking fixtures from one battery cabinet, which is easier to test and maintain than dozens of units and allows ordinary architectural fixtures to serve as emergency lights. The cabinet and its circuits need a suitable room, and the circuits must be arranged so the emergency fixtures come on when the normal lighting in their area fails.

Generator

Buildings with an emergency generator often supply emergency lighting from it through a transfer switch and a dedicated emergency panel. Because a generator takes a short time to start and pick up load, codes and designs address the gap, for example with battery-backed fixtures in key locations. Our guides to emergency power vs standby power and transfer sequences explain how that works.

Spacing and light level

Each fixture's emergency output is lower than normal lighting, and the code's requirement applies along the whole route, not just under the fixtures. Designs that space heads too far apart meet the requirement under each head and fail it in between. A photometric calculation using the fixtures' actual emergency output, mounting height and the real route shows whether the minimum is met everywhere.

A typical case

A single-storey office is renovated from private offices into an open plan. The original emergency lights were in the old corridor, which no longer exists, and two exit signs now face blank walls. Walking the new routes shows that people at the back of the open area have to cross most of the floor to reach an exit, past rows of desks with no emergency lighting at all. The redesign traces the new principal routes, adds battery-backed fixtures along them and at the two exit doors, relocates the exit signs and adds a directional sign where the route turns, and adds a unit outside the rear exit where the path continues to the parking lot. A photometric check with the emergency output confirms the minimum along the whole route.

A design checklist

• Draw the exit routes from every occupied area, including outside the exit doors.
• Identify every space where the applicable code requires emergency lighting.
• Mark doors, stairs, landings, turns, level changes and safety equipment along the routes.
• Choose the power source for each area: unit equipment, central battery or generator.
• Run a photometric calculation with emergency output and confirm the minimum is met everywhere on the route.
• Confirm battery duration meets the required time, with allowance for battery ageing.
• Check voltage drop on remote head circuits.
• Lay out exit signs, including directional signs where the route turns.
• Make testing easy: accessible units, self-diagnostic or remotely monitored equipment where it suits the building, and clear labelling.

Common mistakes

• Lighting the corridor but not the open-plan route that leads to it.
• Forgetting the exterior landing and path outside an exit door.
• Remote heads at the end of long, undersized runs that barely glow.
• Units connected to a circuit that does not serve the area, so a local failure does not trigger them.
• Renovations that move walls without moving emergency lights and exit signs.
• Units mounted where nobody can reach them for testing.

How ehZee can help

We design emergency lighting and exit sign layouts for new buildings and renovations, review existing systems against the current layout of the building, and coordinate emergency lighting with generators and other emergency power. Drawings for permit are sealed by a licensed professional engineer where required, and installation is done by licensed electrical contractors under permit. See our lighting design and controls service.

Common questions