Lightning Protection in Denver, CO

Lightning in the Denver area

Denver gets regular summer lightning, and the metro is not hit evenly. Colorado averages about 500,000 cloud-to-ground flashes a year, according to the National Weather Service office in Pueblo. A 2019 study by NWS Pueblo forecasters, using 21 years of Vaisala lightning data, found a relative low on the plains north of Denver, between Denver, Greeley and Fort Collins, at 0.5 to 1.5 flashes per km² a year. South of the metro, the Palmer Divide and Pikes Peak area has some of the most lightning in the state.

Storms along the Front Range usually develop over the foothills in the late morning or early afternoon and move east onto the plains. Lightning peaks statewide in July and August, when monsoon moisture arrives. For the statewide picture, see lightning protection in Colorado.

Homes in Denver, Aurora and the metro

For most metro homes, lightning protection is a choice based on exposure, not a code requirement. A house on a ridge in the foothills, at the edge of open space, or standing taller than everything around it is more exposed than one among taller trees and buildings.

A residential system includes:

• Air terminals (lightning rods) on ridges, chimneys and dormers.
• Conductors connecting them, with at least two paths down to ground.
• Grounding electrodes at the base of each down conductor.
• Bonding to the electrical ground, gas and water piping, and metal on the roof.
• Surge protection for incoming power, data and communication lines.

For homes under an HOA, NFPA 780 allows concealed systems, with conductors run inside the attic and walls. See our residential lightning protection services and the guide to home lightning protection in Colorado.

Commercial buildings

Offices, warehouses, metal buildings, retail centers, healthcare and public buildings each get a system designed for the roof and the equipment on it. Rooftop HVAC units, solar arrays and antennas have to be bonded into the system. We work on new construction and existing buildings, including inspection, grounding and system testing. See commercial building lightning protection and choosing a commercial lightning protection company.

Industrial and oil & gas sites

For plants, storage tanks, tank batteries and oil and gas production sites, grounding and bonding do most of the work, because a spark near flammable vapor is the hazard. See oil & gas facility lightning protection.

NFPA 780 and UL 96A

NFPA 780 is the US standard for designing and installing lightning protection systems. It sets where air terminals go, how big conductors must be, and how a system is grounded and bonded. It becomes mandatory when a code, contract or authority having jurisdiction adopts it. UL 96A is UL's installation standard, and a complete system that passes UL's inspection can receive a UL Master Label Certificate.

When you compare quotes, ask which standard the system will follow and what documentation you will get. Read NFPA 780 explained and UL 96A and the Master Label.

Inspections

NFPA 780 and LPI-175 recommend a visual inspection every year and a full inspection with testing every 3 to 5 years (1 to 3 years for critical facilities). Also have it inspected after a lightning strike or any roof or building work: re-roofing, solar and new rooftop equipment can disconnect parts of a system. An inspection covers air terminals, conductors, bonding, grounding, surge protection and continuity. In Denver, spring is the best time, before the July and August peak. See our lightning protection inspection service and what is tested during an inspection.