Ask the Contractor: Lightning strikes costly, protection is possible
With our recent monsoons, we have seen brilliant electric discharges in the sky, and I am sure we can all agree that lightning is one of the most beautiful displays in nature. It is also one of the most deadly natural phenomena known to man.
With bolt temperatures hotter than the surface of the sun and shockwaves beaming out in all directions, lightning is a lesson in physical science and humility.
This past week, three calls came in with questions on lightning protection. During our monsoons, homeowners lost electronics with the close proximity of lightning strikes.
Surge protectors won’t save your electronics (TV, VCR, PC) if lightning strikes your power line. Surge protectors provide protection for power surges in the line from the power company, but not for lightning.
Home equipment is more vulnerable to surges produced by lightning because of the networking with other equipment throughout the inside and outside of our homes. More and 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 degree Fahrenheit — or about three times as hot as the surface of the sun.
They can be deadly and damage a home in a matter of seconds. Lightning can rip through roofs, can cause structural damage, ignite fires and cause chaos with electronic equipment. Yearly, the number of homes struck by lightning increases and residential lightning losses exceed billions of dollars annually and represent 5% to 8% of all residential insurance claims.
There are four ways in which a lightning strike can cause damage.
The most common damage mode comes from a lightning strike to the network power; phone and cable TV or commonly known as CATV 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 mode of lightning damage is when strikes travel through the ground connecting to your underground cables and pipes and connecting to external wiring such as air conditioners, exterior lights, gate control systems, electronic dog fences, security systems — all of which when struck by lightning will carry into the home.
The third-most-common lightning strike damage is when lightning strikes nearby objects such as trees, flagpoles, and signs that are close to, but not directly connected to the house. When this type of strike occurs, the lightning radiates a strong electromagnetic field that can be picked up by wiring in the house that can 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 a ground rod has been a requirement to be installed in all homes since back to the late ’70s. 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, as opposed to the old traditional ground rods installed in the earth that are very susceptible to electrolysis.
The term UFER is not actually listed in the code books, but it is a term that is widely used nationally and is named after the engineer at UL Lab (Herbert Ufer) who developed the concrete-encased grounding system.
A lightning rod is not commonly used, as it is more expensive and only protects against direct hits. Lightning rod protections systems must be designed by an electrical engineer to U.L. standards. It is quite costly to engineer and install a proper U.L. ground rod array 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 useful in only the extremely rare direct strike scenario. The AC and signal surge protection systems collect the major part of the lightning surge and then directs this surge harmlessly into the building ground. These protection systems greatly reduce the burden on the point-of-use protectors at the equipment. It is important to keep in mind 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 and this is very 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 protect and prevent potential lightning damage up to 99%.
If you have any doubt or concerns that your home is properly protected and/or to verify if there is any sort of lightning protection device installed in your home, an electrician can assist you with the effectiveness of your current system. With monsoon seasons, it is important to make sure your home is in a bubble of protection.
In talking with Jim Johnson, owner of Elan Electric, he recommends whole house surge protectors be used only in conjunction with point- of-use surge protectors. Layered protection is an industry standard.
“They now make regular-looking outlets that have built-in surge protection,” Jim said. “The way a quality surge protector works is by allowing current to run through at normal levels and, when a lightning surge strikes, the protection device diverts all of the current to the ground as quickly as 3 to 5 nanoseconds.”
A nanosecond is a unit of time equal to one billionth of a second. A nanosecond is to one second as one second it to 31.71 years so as they say that is lightning fast!
Remember to tune in to YCCA’s Hammer Time every Saturday and Sunday mornings at 7 on KQNA 1130AM/99.9FM or 95.5FM or on the web at kqna.com. Listen to Sandy and Mike talk about the construction industry, meet your local community partners and so much more.