A lightning protection system is a complete solution designed to protect a structure from a direct lightning strike. It works by intercepting the strike, providing a safe, conductive path for the massive electrical discharge to follow, and then dispersing that energy harmlessly into the ground. It doesn’t prevent a strike from occurring, but rather controls it.

A complete system includes:

• Air terminals (lightning rods): These are strategically placed on the highest points of a structure to intercept the lightning.
• Conductors: Special cables that connect the air terminals to the ground.
• Grounding: A system of ground rods or plates that dissipates the lightning’s energy into the earth.

When lightning strikes, the system’s air terminals and conductors provide a low-resistance path for the electrical current to travel. This directs the lightning’s energy away from the structure and its contents, safely into the ground, preventing fires and structural damage.

Installing a lightning protection system is a specialized job that requires specific training and expertise. Most general electricians, contractors, or roofers don’t have the necessary knowledge or certification. You should only hire a contractor who is certified by a recognized organization, such as the Lightning Protection Institute (LPI), to ensure the system is designed and installed correctly according to safety standards.

While not always mandatory for every building, lightning protection is often required by local building codes for specific types of structures, especially those that are: located in areas with frequent thunderstorms; taller than surrounding structures; used for critical services, such as hospitals, data centers, or emergency services; houses with large groups of people (e.g., schools, stadiums); containing flammable or explosive materials; housing irreplaceable cultural heritage, like museums; or taller buildings with metal frames or cladding.

Lightning Protection Levels (LPLs) are defined in international standards like IEC 62305. An LPL is determined by a risk assessment and corresponds to a specific level of protection against a lightning strike. The higher the level (e.g., LPL I), the greater the protection, as it’s designed to handle more severe lightning currents. The assessment helps determine the appropriate design for the system, including the placement of air terminals and conductors.

A lightning protection system should be inspected and tested by a specialist at least once a year. Regular inspections are critical to ensure all components are in good working order and to check for loose connections, corrosion, or any other damage.

A surge protection device (SPD) is a component of an electrical system designed to protect against voltage spikes, also known as electrical surges. It limits transient voltages by diverting or limiting excess current to the ground, preventing it from reaching and damaging sensitive electronic equipment. SPDs are a key part of a comprehensive lightning protection plan, as lightning can cause powerful surges even without a direct strike.

Surge protection devices contain a non-linear component, most commonly a Metal Oxide Varistor (MOV). During normal operation, the MOV has a very high electrical resistance and acts as an open circuit, allowing electricity to flow through your system. However, when a voltage surge occurs, the SPD’s internal components quickly switch to a low-resistance state, diverting the excess energy safely to the ground. Once the surge has passed, the SPD returns to its high-resistance state.

In many regions, yes. Building codes and regulations, such as the National Electrical Code (NEC) 2020 in the U.S. and the 18th Edition Wiring Regulations (BS 7671) in the U.K., have made the installation of SPDs mandatory for new residential and commercial buildings. The need for surge protection is growing due to the increasing number of sensitive electronics in modern homes and businesses.

You should consider installing surge protection: in new construction or major renovation projects; if you live in an area with frequent thunderstorms or grid fluctuations; to protect sensitive and expensive equipment like computers, servers, and high-end home entertainment systems; and for homes with smart appliances, solar panels, or EV chargers, as these systems are particularly vulnerable to surges.

A comprehensive approach uses a layered defense: whole-house surge protection, which is the first line of defense and is installed at your main electrical panel to protect all appliances and electronics in your home from external surges; and point-of-use surge protection, which are surge protector power strips or outlets that provide a second layer of protection for specific, sensitive equipment like computers, TVs, and entertainment systems.

For a house, a whole-house surge protector is highly recommended. The specific rating you need depends on your home’s electrical service size and the amount of electronics you have. Whole-house SPDs are rated in kiloamps (kA), which indicates how much energy they can absorb. A 40kA to 80kA rating is sufficient for most average-sized homes, while a 100kA to 120kA rating is ideal for larger homes or those with a high density of valuable electronics. For more information, a licensed electrician can assess your needs and recommend the best surge protection solution for your home.