Restrike Time. The differences in restrike time among the various
lamps (see Table 9) influence the selection of security lighting systems and
concepts. For example, high-pressure sodium lamps are the primary light
source of most security systems because of their efficiency (140 lumens/W).
However, these lamps are not without deficiencies. From a cold start, a
high-pressure sodium lamp warms up to full light output in about 10 minutes.
It will usually restrike in less than 1 minute and warm-up in 3 to 4 minutes.
During this warm-up interval, the lamp cannot be expected to operate at full
light output, and this reduced capacity may be important in many
high-security applications. Because of this restrike interval, incandescent
lamps are sometimes used as the emergency backup light source because of
their short restrike time. The evaluation of any security lighting system,
particularly one requiring continuous illumination, requires careful analysis
of lamp life, energy consumption, and restrike time. The security engineer
who has determined that short restrike time is a critical performance
parameter should determine whether it is economically feasible in relation to
increased lamp replacement and energy costs.
Maintaining Essential Security Support Functions
Overview. Essential exterior site functions that support site and
facility security include security power supply, general power supply,
communications, and security control.
Security Power Supply. Both regular and standby power sources
should be provided for IDS and security lighting. In some cases, dual
emergency backup power sources may be required, particularly if power
IDS lines should be well protected, usually by burial. In the case of light
poles, cabling should be internal to aluminum or steel poles. Standby power
sources must be protected from sabotage by facility hardening and IDS
coverage. Standby power sources should be configured for automatic
activation when required.
General Installation Power Supply. Some of the best tools used for
penetrating hardened facilities rapidly are electrically powered. Although a
sophisticated attacker will probably not let himself be dependent on facility
power sources, it is worthwhile to consider arrangements where the general
power supply to a facility exterior and just outside any key interior
barriers (other than that required for essential services such as IDS) is
either normally shut off during nonworking hours or can be shut off remotely
by the security forces. Switch and fuse boxes must be protected.
Communications. To the extent feasible and practical,
consideration should be given to hardening both internal and external
communications lines so that security forces will not be easily deprived of
their use during emergencies. As mentioned above, communication lines
essential to IDS alarm assessment should be hardened and protected with
fail-safe features. Phone jacks for security personnel should be provided,