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CLAMPING DOWN ON LIGHTNING TECH TALK by Bob Dolph Bob Dolph has served in various technical management and advisory positions in the security industry for 30+ years. To share tips and installation questions, E-mail Bob at bdolph.ssi@gmail.com. Check out his Tech Shack blog at www.securitysales.com/blog. bdolph.ssi@gmail.com Smart security practitioners know better than to ever underestimate the power of Mother Nature. That includes lightning strikes, which can wreak havoc for systems unless they are properly grounded and equipped with surge protection. T he topic of lightning surge protection is always relevant, especially during these peak summer months. Residing in what has been dubbed Te Lightning Strike Capital of the World — Central Florida — I have a pretty good vantage point on this subject. So this month we will review best practices, shed light on tips you may have not heard, and investigate technology that could make your lightning fghting days easier and those eforts more reliable. Sometimes installers and technicians deploy faulty reasoning, thinking, "If I do not ground my equipment, it will be less attracted to lightning and I will have less equipment loss." While this may appear to be true the practice is dangerous to both equipment and, even more importantly, life safety. If you do not give lightning surges direction to ground they will fnd their own course. Many in security have experienced this when sensitive reeds in window alarm contacts have been permanently frozen shut. Also remember from a liability perspective that most alarm panel manufacturers recommend some sort of power connections for their internal surge suppression to work. You should always follow the manufacturer's recommendations. Lightning surge suppression technology is only as good as fnding and verifying good electrical ground resistance. Tis is a particular challenge in highly active areas like Florida. While we will mainly discuss electrical surges from lightning, also be mindful that the quality of power from the util- 22 / SECURITYSALES.COM / JULY 2013 ity company is one of the principal destroyers of equipment. SOLID GROUNDING STRATEGIES Te most important initial element of any transient voltage surge suppression (TVSS) is a low impedance ground connection. Articles 100 and 250 of the National Electrical Code (NEC), or NFPA 70, describes an acceptable ground as being rated at 25 Ohms of resistance or less. However, our goal is to achieve less than 5 Ohms. Anything above this can start to adversely afect the performance of surge protection devices (SPDs). Remember that proper electrical grounding and bonding practices typically follow the directives of your local AHJ. So if you have not yet done so, check with your AHJ for grounding implementation guidelines. Where are some of the best locations in a facility to fnd a good ground connection? Tey are electrical service grounds, grounded building steel, local electrical ground and dedicated driven rods. Did you notice anything missing from this list? Yes, we no longer reference the now infamous cold water pipe. Most modern cold water pipes are not metal but PVC, even though on the surface they appear to be metal. As many dealers that live in areas such as mine will tell you, fnding a good and consistent earth ground can be tricky. In Florida, sandy soil can measure good as water tables rise in the summer, but ground resistance can become high in the drier winter months when water tables drop. In sandy arid areas like the Southwest it can be even worse.