Appendix F - Preventing Lightning Damage - Secura Key SK-ACPE User & Installation Manual

SK-ACPe
APPENDIX F
PREVENTING LIGHTNING DAMAGE
SURGE PROTECTION FOR ACCESS CONTROL SYSTEMS
Access Control equipment is susceptible to damage from lightning, especially when installed
outdoors. Voltage spikes which travel through buried data cables, telephone lines or AC power
lines can damage Access Control equipment indoors, as well.
The SK-ACPE-LE is equipped with Gas Discharge Tube Surge Arrestors on the RS-485 communications
lines (J8). For these devices to work properly, the SK-ACPE chassis ground (located on the circuit
board, just to the left of J8) must be connected to a good Earth Ground such as a 10' Copper
Ground Stake (best) or AC Power Ground.
While nothing can protect equipment from a direct lightning hit, surge protectors can help to minimize
the damage caused by nearby lightning strikes. Surge protectors operate by connecting Transorbs
or Varistors from data lines to ground. Surge protectors have no effect on normal circuit voltages,
but can act quickly to divert large voltage spikes to ground and away from sensitive components.
Although Secura Key equipment includes on-board surge suppression, properly grounded off-board
devices will provide the best protection.
WHERE TO INSTALL SURGE PROTECTION
• On the AC line voltage input to the PC. (A UPS with surge protection is recommended).
• On the AC line voltage input to any transformer or DC Power Supply connected to an SK-ACPE or Modem.
• On RS-485 data lines connecting an SK-ACPE to a PC, or to other SK-ACPE's.
• On the power supply of a NET-CONV-P RS485 Converter (if used).
• On RS-232 data lines from SK-ACPEs to PCs, Printers or Modems.
• On Telephone lines connected to Modems.
• On Data lines connecting card readers or keypads to the SK-ACPEs.
SURGE PROTECTORS
There are many manufacturers of surge protectors. Some are designed to protect a single type of
circuit such as high voltage AC, low voltage DC or telephone lines. Secura Key offers two multi-
function surge suppressors that are well-suited to protecting access control equipment. The DTK-XR
is a good choice for protecting an SK-ACPE panel from power, data and telephone line surges. If
the card readers or keypads attached to the SK-ACPE are located outdoors you may also wish to
install DTK-CR protectors on each reader circuit. Wiring instructions for these surge protectors
appears on pages F4 and F5.
PROTECT BOTH ENDS OF DATA LINES
Surge Protectors should be installed at both ends of all Data Lines.
InStAllAtIon & oPerAtIng MAnuAl
F-1