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Sat, Feb. 29

Ask the Contractor: Protection from lightning strikes is important

This past week, three calls came in with questions on lightning protection, and with our monsoons 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.

At the Home Show (May 17-19), several homeowners stopped me and asked about whole-house surge protection, so here is a re-run of a column we did a few years back. Enjoy.

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 degrees F — or about three times as hot as the surface of the sun — and 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 bolt 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 the strike travels 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, and security systems — all of which when struck by lightning will carry into the home.

The third most common lightning strike damage is when lightning hits 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, damaging 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.

An UFER ground or a grounding rod has been a requirement for installation 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 rod installed in the earth, which is 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 (formerly Underwriters Laboratories), 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 protection systems must be designed by an electrical engineer to UL standards. It is quite costly to engineer and install a proper UL 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 only in the extremely rare direct strike scenario. The AC and signal surge protection systems collect the major part of the lightning surge and then directs the 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’s 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 by as much as 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 monsoons — our seasonal rains that come with lightning, it is important to make sure your home is in a bubble of protection.

In talking with Jim Johnson, owner of Elan Electric, Jim recommends only whole house surge protectors be used 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 a nanosecond.”

A nanosecond is a unit of time equal to one billionth of a second. A nanosecond is to one second, as one second is to 31.71 years — so that is lightning fast!

Remember to tune in to YCCA’s “Hammer Time” every Saturday or Sunday at 7 a.m. on KQNA 1130AM, 99.9FM, 95.5FM or online at Listen to Sandy to Mike talk about the construction industry meet your local community partners and so much more. You will be entertained.

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