When Lightning Strikes Alarm Systems
Think Ahead When Installing
As mentioned earlier, one common application where lightning can cause considerable damage involves integrated systems across multiple buildings. Because of the matrix of wires that travel to and from each building, being installed either overhead or underground, the propensity for damage is considerable.
In this case a single head-end system may be employed to provide a number of low-voltage services, such as fire, security and/or CCTV protection. Here, especially proper precautions must be taken, such as the use of quality surge protection.
One case in point is a motel with multiple buildings serviced in the summer of 2008, by Nick Markowitz, owner of Markowitz Electric Protection of Verona, Pa. According to Markowitz, the location experienced a lightning strike that damaged a fire alarm system, three cameras and a washing machine. The lightning affected systems in three separate buildings by first entering a restaurant and then traveling throughout the entire campus.
“The camera system is one of those cheap cameras-in-a-box deals that uses four-wire telephone cable. One of the cameras is located in the restaurant and is fine, but another one took a hit and the wiring was damaged,” says Markowitz. “The other two cameras were converted from phone wire to inline powered coax and lightning took out the converters and power injectors.”
Lightning entered through one of the cables that crossed between the buildings, Markowitz reports. A close examination revealed that there wasn’t any surge protection on any of the low-voltage cables that serves video or any other centralized system. And yet damage was spotty, which Markowitz found puzzling considering the severity of the hit.
“I find it strange that the monitor and one of the other cameras were fine but all the rest was trashed. Usually when lighting strikes like this, everything goes at once,” he adds.
Equipment Circuit Design Changes
Manufacturers have changed the way they construct and package components contained in their low-voltage systems. Included is the way those components are installed on PC boards. Both of these factors have altered the way alarm technicians protect their electronic systems from lightning, says Pecore.
“In 1997, Stormin Protection Products officially became an engineered lead business because the projected sales in the area of low-voltage surge suppression for fire alarm, CCTV and access control systems will be in greater demand as the progress of SMT [surface-mount technology] literally took over the industry,” says Pecore.
SMT technology allows manufacturers to reduce power consumption as well as extend the length of time batteries will provide backup power. If nothing else SMT components have allowed manufacturers to reduce battery size to meet a specific code requirement, such as standby time. SMT technology poses a problem because it represents a relatively low impedance to lightning.
“SMT technology for an old guy is a dirty word. It spells out one thing, nothing but trouble,” says Pecore. “Manufacturers took all the linear and high capacitance devices off the board and left me with a featherweight that if I hiccup just right, it will blow.”
Design engineers have eliminated linear power supplies, replacing them with Wheatstone bridges. Also, low-imp
edance capacitors and resistors have replaced heavy-duty capacitors and resistors, and smart chips have replaced entire printed circuit boards.
“Low Pico Farad devices have also replaced other components — all for the sake of reducing current draw,” says Pecore. “As a result of these changes, fire alarm panels (and other electronic systems) have become more susceptible to surges, impulses and ground strikes.”
The idea is to raise the impedance of the panel, not lower it, and to do this the installer has to look for ways to create an alternate path that looks more inviting to high-voltage lightning than the panel’s motherboard.
According to Pecore, the answer is an inline series hybrid three-stage, two-tank circuit that works to impede strike current while shunting it to ground. This is accomplished by focusing on the characteristic frequency associated with lightning.
Al Colombo is an award-winning writer who has covered electronic security and life safety since 1986. To reach Al, visit www.firenetonline.com or E-mail [email protected]
Security Is Our Business, Too
For professionals who recommend, buy and install all types of electronic security equipment, a free subscription to Security Sales & Integration is like having a consultant on call. You’ll find an ideal balance of technology and business coverage, with installation tips and techniques for products and updates on how to add sales to your bottom line.
A free subscription to the #1 resource for the residential and commercial security industry will prove to be invaluable. Subscribe today!