Emergency lighting on construction sites

Background

Evacuation routes on construction sites often contain construction materials, electrical switchboards, portable equipment and other obstacles.

Principal contractors have management and control of construction sites and have the primary obligation to ensure there is enough lighting for workers to safely evacuate in emergencies and allow emergency or repair personnel to access the site.

On sites where there is not enough natural lighting — or in the event of a loss of normal lighting — lighting to mark evacuation routes is normally provided by installing battery powered emergency lighting and exit signs.

Emergency lighting should also be installed directly above and in front of switchboards to help restore normal lighting after a fault occurs.

Emergency lighting requirements

Planning

Include employee evacuation in the project's planning phase.

When tendering for electrical contractors, the principal contractor should include all needs for emergency and exit lighting during the various phases of construction as part of the requirements for the construction-wiring tender.

Planning should also take into account whether temporary lights are mounted to the soffit or the walls of the structure.

Evacuation routes

As part of the site's emergency response plan, the principal contractor should designate evacuation routes for the various work areas.

The routes should be regularly reviewed over the life of the project to ensure they remain effective as the site layout changes and also to ensure that access routes are clear of obstructions.

In multi-storey buildings, the principal contractor should define any stairway that should be treated as an emergency evacuation route and are kept clear of obstructions at all times.

When emergency lighting is required

Site evacuation routes require emergency lighting where:

• work is outside full daylight hours (emergency lighting may need to be installed as the year progresses and days shorten)
• natural lighting does not maintain a sufficient lighting level. For example, basements, internal passageways or shading from near buildings

Note: If any work area, including under temporary support structures, for example, formwork decks, is not sufficiently lit by emergency lighting, then additional emergency lighting should be installed to light the work area to allow safe exit.

Emergency lighting on tower cranes

When considering lighting levels to safely access a tower crane, or for other work, the principles within AS/NZS 3012 should be followed. Install an emergency light at each tower section landing.

Emergency lighting — construction wiring

The emergency lighting level should be provided for a minimum of 1 hour after loss of normal lighting in the area according to clause 2.7.3 of AS/NZS 3012 Electrical installations on construction and demolition sites.

Where a circuit contains detachable connections for emergency lighting, for example, installation couplers, these detachable connections should prevent unauthorised disconnections.

When required, install emergency lighting using one of the following methods:

Method A

Provide an average of 20 lx at 900mm above the floor level along the centre line of the corridor.

Method B

Using luminaires — complying with the luminaire classification, mounting height and spacing as specified in the tables in AS/NZS 3012.

Method C

Installation based on calculations of illuminance — complying with the requirements of AS/NZS 2293.1, and using a minimum horizontal illuminance of 3 lx.

Exit signs

Exits signs should not be positioned more than 1m above or 2m in front of the exit. If the evacuation route turns, or does not lead directly to an emergency exit, then exit direction arrow signs that point towards the emergency exit should be placed at each change of direction.

Exit signs, including exit directional arrow signs, should be internally lit so they can be seen through smoke and have battery back-up. In specific circumstances, however, clause 5.3 of AS/NZS 2293 Emergency escape lighting and exit signs for buildings, states that externally lit signs may be suitable. This is only in areas that have appropriate means for automatically exhausting or excluding smoke. Exposure to open air does not meet this requirement. Externally lit signs, where permitted, must be directly lit by an emergency light.

Reusing emergency light fittings

Emergency light fittings are often reused from previous sites or other temporary installations. For example, from completed lower floors of a multi-storey site.

As the lamps and batteries age, the drop in light output should be managed to ensure minimum emergency lighting levels are maintained.

Protecting emergency lighting

Emergency light fittings should be made from impact resistant material like polycarbonate or be fitted with mechanical protection such as wire cages.

Testing of emergency lighting

Emergency lighting should be verified, depending on the installation method selected. For Emergency lighting installation methods A and C, check the light reading using a light meter. For installation method B, install according to specifications in AS/NZS 3012.

Emergency lighting should be periodically inspected and electrically re-tested every 6 months, including a discharge test to ensure emergency lighting maintains the required level (based on method A, B or C) for at least 1 hour after the loss of normal lighting.

Records of testing should be kept on site and made available for auditing.

Measuring the light level with a light meter

Checking the light level cannot be based on a single measurement. It should be taken as an average over the whole route or portion of the route being measured. For example, a passage way or stairwell.

For consistency, the following method (also illustrated in Figure 1) should be used to determine if the designated evacuation route achieves the 20 lx lighting level.

Take readings:

• with a calibrated light meter held horizontally at a height of 1m above the floor
• 1m from the start of the route and at 1m intervals along the route
• where shadows are not cast onto the meter

Add all the readings together and divide by the number of readings taken to calculate the average light level. This should not be less than 20 lx. Records of lighting levels should be kept onsite for reference.

Examples of calculated average light levels

• (25 + 18 + 15 + 12 + 16+ 22) divide by 6 readings = average of 18.0 lx (Fail)

• (30 + 22 + 18 + 5 +19 + 30) divide by 6 readings = average of 20.7 lx (Pass)

Removal of temporary emergency lighting, transitioning to permanent emergency lighting

Before the permanent emergency lighting is commissioned and the construction lighting is decommissioned, the principal contractor and the electrical contractor — in consultation with the HSR and/or site safety committee — should determine in writing that the site is at a stage of completion where permanent emergency lighting can replace the temporary emergency lighting.

It is imperative to ensure that workers safety is managed throughout this process.

The principal contractor and electrical contractor should consider:

• construction work that is complete (specific to area that the temporary emergency lighting to be removed is servicing)
• if fit off, electrical, plumbing, dry fire, and mechanical works are complete
• if electrical commissioning is complete (Dead testing is performed on the circuits when they are de-energized, and form the initial testing of the circuits)
• hallways and rooms are cleared of building materials
• doors and joinery installed and that no further fixing in any wall or ceilings is needed
• access hatches complete and closed and that there is no open penetration
• that permanent lighting, once energised, must not be controlled by motion sensor or reduced in illumination capacity until hand over has occurred

Display appropriate signage in energised zones to ensure that workers are aware that permanent wiring has been installed.

Consider a permit system for working near live services to prevent unauthorised personnel from working in an energised environment.

The principal contractor and the electrical contractor should have regard to the AS/NZS 3000 Wiring rules and satisfy themselves that the site is at an appropriate stage of completion.

The Wiring Rules (AS/NZS 3000) Appendix E provides information for Electrical Installation Requirements in National Construction Codes.

The National Construction Code (NCC) for fire safety includes:

• emergency evacuation lighting, exit and directional arrows
• standby power systems for fire and smoke control systems, and emergency escape lighting in buildings that contain atriums

The Wiring Rules (AS/NZS 3000) Appendix H2 Particular Wiring System Application AS or AS/NZS 2293 series, Emergency escape lighting and exit signs for buildings.

AS 2293.1, Emergency escape lighting and exit signs for buildings, Part 1: System design, installation and operation, requires a rating of WS4X for submains and certain circuits associated with central emergency lighting systems.