Emergency Lighting Spacing Tables.
To allow emergency lighting designs to be performed as required by BS5266 pts 1 and 7, certain factors need to be included to ensure that design allows for the ‘worst case’ conditions.These factors are:
- Ballast lumen factor (BLF) — The percentage of light given out when the ballast is in the emergency condition.
- S factor — Compensates for the ageing of the lamp.
- K Factor — Compensates for the reduction of the supply voltage as the battery discharges.
When the factors are applied to the initial lumen output of the lamp they give the Emergency Lighting Design Lumens (ELDL) in the table below. These can be used for spacing calculations.
CONVERTED MAINS LIGHTING LUMINAIRES — DESIGN PROCEDURE.
Use the table below to determine the minimum emergency lamp output for the lamp/circuit to be used. This can be used with the spacing tables.
Choose the appropriate spacing table with the correct polar curve and the value of the output is similar the chosen fitting (LOR and at the nadir). Any variations can be compensated for, by determining the ratio for the lamp output obtained from the table below.
Using the specified mounting height & lamp type the spacing limits for escape routes and/or open areas can be determined.
If required, it is possible to calculate different values of minimum light levels. This is simply obtained by determining a ratio for the lamp output value. So to ensure a minimum of 10 lux on the centre line of an escape route (instead of 1 lux) the value given in the spacing tables must be multiplied by a factor of 10.
Therefore a 1500 lumen lamp output gives the same spacing at 10 lux as a 150 lumen lamp does for 1 lux.
The following spacing tables incorporate a 20% allowance for build up of dirt on the diffuser.
Click here to see the ballast lumen factors table
Click here to see spacing tables
Typical Electric Data