Ask the Contractor: Protect your home against lightning
With monsoon season upon us and the dissipation of lightning, surge protection has become a much more complex and important issue because the value of electronic equipment in a typical home has increased enormously. Equipment is also more vulnerable to surges produced by lightning, because of the networking with other equipment throughout the inside and outside of our homes.
More homeowners are becoming aware of the need to protect their homes from lightning strikes and how do we do that? A single bolt of lightning can exceed 300,000 amperes, over one gigavolt (one billion volts) with temperatures as high as 36,000 degrees Fahrenheit – about three times as hot as the surface of the sun. Yearly, the number of homes struck by lightning increases and residential lightning losses exceed billions of dollars annually, representing 5 percent to 8 percent of all residential insurance claims.
Lightning can cause damage in four ways:
• Most common is a lightning strike to the network power, phone and cable TV wiring. This network, a main collector of lightning surges, transfers directly into the home and then to all of your connected equipment.
• The next most common type of lightning damage is when strikes travel through the ground, connecting to your underground cables and pipes and to external wiring such as air conditioners, exterior lights, gate control systems, electronic dog fences and security systems - all of which will carry lightning into the home.
• Third most common is when lightning strikes nearby objects, such as trees, flagpoles and signs, that are close to, but not directly connected to the house. Lightning radiates a strong electromagnetic field, which can be picked up by a home’s wiring and damage equipment.
• The last mode of damage is a direct lightning strike to the house.
Our National Electric Code requires certain grounding, bonding and protection features that are intended to protect against lightning. These safeguards greatly reduce personal injury; however they are somewhat inadequate to prevent damage to electrical and electronic equipment.
A UFER ground, or ground rod, has been a requirement to be installed in all homes since back to the late 1970s. The UFER ground is installed prior to the concrete pour of the footers. The ground wire is run to the rebar that is encased in the concrete footers. UFER refers to the fact that the grounding system is encased in concrete, which keeps the grounding resistance steady over many years.
The term UFER is not actually listed in the code books, but it is widely used nationally and is named after the UL Lab engineer (Herbert Ufer), who developed the concrete-encased grounding system.
In order to allow for enhanced protection against lightning, there are options such as installing Lightning Protection Systems, surge protectors on the AC power wiring, additional surge protections on signal wiring and point-of use-protection at the equipment being used.
The Lightning Protection System is only useful in the extremely rare direct-strike scenario. The AC and signal surge protection systems collect the major part of the lightning surge and then direct this surge harmlessly into the building ground. These systems greatly reduce the burden on the point-of-use protectors at the equipment. Remember that the effectiveness of this protection system depends on the integrity of the building wiring. A good surge protection system installation should include testing of all receptacles to be used. Most new homes are built with power, phone and CATV entry points close to one another; this is desirable and makes it easy to mount the AC protectors and signal protectors close to the main building.
Whole House Protection, sometimes called Complete Home Surge, systems are becoming more popular. A lightning protection system properly installed can prevent potential lightning damage up to 99 percent.
If you have any concerns that your home is properly protected and/or to verify if there is a lightning protection device installed in your home, contact an electrician.
Remember to tune in to YCCA’s Hammer Time twice each weekend Saturday and Sunday at 7 a.m. on KQNA 1130 AM/99.9 FM or the web kqna.com. Listen to Sandy and Mike talk about the construction industry and meet your local community partners and contractors.