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 therefore have the primary obligation to ensure lighting is sufficient 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 at or next to site switchboards to help restore normal lighting after a fault occurs.
Employee evacuation should be included in the project’s planning phase.
When tendering for electrical contractors, the principal contractor should include all needs for emergency lighting during the various phases of construction as part of the requirements for the construction-wiring tender.
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.
In multi-storey buildings, personnel will use any active stairway during an emergency, so each active stairway should be treated as an evacuation route.
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 the evacuation route lighting, then additional emergency lighting should be installed to light the work area to allow safe exit.
The emergency lighting level shall be provided for a minimum of 1 hour following loss of normal lighting in the area according to clause 2.7.3 of AS/NZS3012 Electrical installations on construction sites and demolition sites.
Where a circuit contains detachable connections for emergency lighting, these detachable connections shall prevent unauthorised disconnections (for example, installation couplers).
When emergency lighting is required, it should be installed using one of the following methods:
Provide an average of 20 lx at 900mm above the floor level along the centre line of the corridor.
Using luminaires — complying with the luminaire classification, mounting height and spacing as specified in the tables in AS/NZS 3012.
Installation based on calculations of illuminance — complying with the requirements of AS/NZS 2293.1, and using a minimum horizontal illuminance of 3 lx.
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 with battery back-up so they can be seen through smoke. In specific circumstances, however, clause 6.3 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.
Readings should be taken:
- 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
Figure 1: Suggested process for reading the light level
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)