NVent Erico Residential Lightning And Surge Suppression Solutions

HOW TO PROVIDE PROTECTION

A direct strike lightning protection installation for the home consists of the following four essential components

(standard practice is defined within the UL96A installation requirements for lightning protection systems):

1. Air Terminals

The function of an air terminal is to capture the lightning strike, therefore each air terminal needs to be located on a point on the structure that has a high probability of being struck by lightning. Some of these key design rules are stated below:

a. Air terminals shall be provided on all roof projections (such as dormers, chimneys).

b. Air terminals shall extend at least 10 inches above the roof-line or area to be protected.

c.Air terminals greater than 24 inches in height shall be braced.

d. Air terminals shall be placed within 2 feet of roof ridge ends or within 2 feet of outside edges or corners on flat roofs.

2. Interconnecting Conductors

The function of the conductors is to provide an electrical path from the air terminals to the grounding system. Some of the key requirements relevant to residential homes are stated below:

a. No less than two down conductors shall be provided from the air terminal system to the grounding system. These down conductors from the roof to ground level shall be installed at opposite ends of the structure.

b. There must be at least two conductor paths to ground for each air terminal (some exceptions may exist based on the structure.)

c. All rooftop metallic objects (i.e. antennae, gutters, vent) should be bonded to the conductor system.

d. The conductor can be either copper or aluminum and must be UL listed for the application of a lightning conductor. 

3. Protection of Electrical Equipment Within the Home

Sensitive electronics are now present in a range of equipment in the home, including TVs, home entertainment systems, home office equipment, security alarm systems, air conditioning systems and most other home appliances. Although direct lightning strikes are the most spectacular form of energy that can damage your valuable household electrical equipment, it’s only one source of damage. Other sources include operation or switching of electrical equipment and indirect lightning surges on the power network. It is important to note that lightning does not need to directly strike a power line or your home to result in damaged equipment within your home. A lightning strike several hundred feet away can induce a damaging surge into the electrical, telephone or other services entering your home, even to underground cables. It is possible to provide protection against this threat by coordinating a “whole house” surge protection plan. A hardwired surge protective device installed on your electrical panel can help protect electrical equipment within your home. All other incoming conductive lines must be considered including, but not limited to, telephone, cable TV and satellite dishes.

4.  Grounding System

The function of the grounding electrodes (rods) is to provide a point for the lightning discharge to enter the ground. It typically consists of a copper-bonded ground rod, driven into the ground, outside the perimeter line of the structure.

WARNING: Care must be taken that no services exist in the ground beneath before driving any ground electrodes.

A ground electrode, typically driven to a depth of 10 feet is required at the base of every down conductor. Some of the requirements for lightning protection grounding, relevant to residential homes, are stated below:

a. Ground electrode shall be at least ½ inch diameter by 8 feet long. Copper-bonded electrodes are recommended.

b. If rocky soil, services underground, or other reasons prevent a vertical electrode from being driven, a horizontal conductor, buried at least 18 inches below the ground, and extending no less than 12 feet away from the structure can be used.

c. All grounding systems shall be interconnected using the same sized (copper) conductor that was used as the lightning conductor. These grounded systems include lightning protection, electrical service ground, telephone service ground bond, antenna system (i.e. satellite TV) grounds. Note the electrical and telephone grounds should (by code) already be bonded, however, it is advisable to confirm this with a qualified technician. The nVent ERICO Intersystem Bonding Termination (IBTB) is ideal for residential bonding, is UL Listed and meets the requirements of NEC.

d. In a similar method to point c above, interconnecting bonds are required to all underground metallic piping systems. This includes water piping, gas piping, underground conduits, or well casings within 25 feet of the home. In the case of metal pipe systems that are interconnected with a section of plastic pipe, or non-conductive fixing (joint) this section of the pipe shall be bridged using a lightning sized conductor and purpose designed pipe bond.

e. If all services are already bonded prior to the lightning protection is installed, it is only necessary to bond from the nearest lightning protection ground electrode to the water pipe system.