Below is some technical installation information provided by our equipment manufacturer. It will give you some idea of the factors that go into designing a lightning protection system.

LOCATING AIR TERMINALS
In placing air terminals form the base or saddle so that it fits snugly over the ridge. Fasten it firmly being careful not to mash it into roofing materials so that it could cause a leak. If roof is of asbestos shingle or similar hard material then you must drill a hole to set your fasteners.

Air terminals must be placed within two (2) feet of the ends of ridges, corners or edges of flat roofs and roofs of prominent dormers and lower elevations. Air terminals must not be spaced more than 20' apart.
1/8 Pitch or less
Less than 40'
1/4 Pitch or less
More than 40'
Same rule as above
Gently sloping

Air terminals shall be placed on ridges, corners and edges of roofs having a pitch of 1/8 or less if building is 40' wide or less, or a pitch of 1/4 or less if building is 40' or more wide.

Flat and gently sloping roofs that exceed fifty (50) feet in width require additional air terminals on the flat and gently sloping areas. These air terminals shall be spaced not over fifty (50) feet apart in all right angle directions.

Flat Roof 200' x 180'
Low Pitch Roof 100' x 120'

CHIMNEY TERMINALS
Chimney air terminals shall be attached to the chimney so that no outside corner of the chimney is more than two (2) feet from the air terminal. The air terminal shall be anchored to the chimney or may be secured by an acceptable metal band around the chimney.

Chimney points must extend at least 10" above the top of the chimney. Copper chimney points must be lead covered; aluminum need not be covered. At least two anchors or straps must be used to fasten terminal to chimney. Where the chimney is tall, use a straight base and bring the cable straight down the chimney to the roof conductor and splice on with a tee connection. This makes a job much more attractive.

If a chimney is larger than 18" x 24", two air terminals are required, one at each end. These two terminals must be tied together at the base. On low chimneys this will be at the roof line but on high chimneys this must be done two (2) to three (3) feet from the top. When making the tie be sure you run the cable straight and level around chimney so it will appear neat.

Air terminals shall be placed on all chimneys, vents and enclosures, including prefabricated metal chimneys, vents and enclosures with metal thickness less than 3/16 inch (4.8 mm) when such chimneys, vents or enclosures are not within a zone of protection. If the metal is 3/16 inch thick or more, only bonding is required.

Always set chimney points on the back side of the chimney where possible so they won't appear unsightly.
On some very large fireplace chimneys, four air terminals are required (when width is over four (4) feet). You can use four (4) special lead covered flat bases set on the flat cap of the chimney and tinned copper or bare aluminum cable around cap connecting these bases together. Then only two leads down to roof conductor will show and your job will look much better. Points set on chimneys that are off the side of the ridge shall not be considered in the spacing of ridge points. Only air terminals placed on chimneys which are directly in line of ridge may be considered a ridge terminal.

DORMERS
Prominent dormers are determined by the following rule. Measure the height from the finished grade level to the main ridge. From a position at grade level, directly below the main ridge, measure out horizontally two times this height. At this point, sight to the main ridge. If the entire dormer is under the line of sight, the dormer is not prominent. If any part of the dormer extends above the line of sight, it is considered prominent and shall be protected. If uneven terrain surrounds the structure, scale drawings shall be made to assist in this determination.

This rule shall also apply to dormers located near other higher parts of the structure such as chimneys, side gables, and towers. In these cases, measure the distance from graded level to the top of such projections and proceed as outlined. Dormers whether ridge, round or flat roof use the same rule.

Dead Ends mean air terminals with only one path to ground. Air terminals may be "dead ended" on dormers and chimneys provided the conductor run from the air terminal to the main roof conductor is not more than sixteen (16) feet long and maintains a horizontal or downward coursing. "Dead ends" on main ridges or wings off main ridges are not acceptable. Small dormers that are located near the lower edge of the roof can be protected in a neat manner by running the cable underneath the corner board next to the sheathing, then over to the main downlead under the edge of the shingles at the gutter. Do not anchor cable to gutter since the holes will cause damaging leaks.

TREES
The data included on the below has been prepared using the design recommendation for tree Lightning Protection published by the Underwriters' Laboratories, Inc., the National Fire Protection Association, the United States Department of Agriculture and the Nations Bureau of Standards. Added to the information from these sources are the fact gained from the manufacture and installation of the highest quality of Lightning Protection equipment by the ROBBINS LIGHTNING PROTECTION COMPANY and our associated companies with well over 100 years experience.

The care, maintenance and protection of our trees must be considered a real responsibility for each person so we can keep in touch with the past, make the present more enjoyable and provide a helping hand to the future. We can preserve our trees by management of disease and insects through use of chemical sprays and damaged tree removal. We can install Lightning Protection to protect against one of the major causes of tree loss. We can plant a new tree to replace one lost or simply to assure that future generations will be able to enjoy the majesty of a living natural specimen.

Lightning damage to trees not only affects the tree, but case histories show the side effects can be extremely serious. A bolt of lightning can strike a tree, jump to a house, setting the house afire or exploding it without fire. The lightning bolt can set the tree on fire, starting a forest fire with the resulting loss of many trees, buildings and possibly lives.

The monetary value of trees may be difficult to determine. On a residential lot the existing trees easily double the total value of the property. The park was designed around trees to make it more appealing to a greater number of people. The municipal or private golf club was designed around existing trees. Action must be taken to prevent the loss of a great monetary value. Lightning Protection for trees is low in cost and will last for the life of the trees.

We recommend the application of ROBBINS LIGHTNING PROTECTION SYSTEM to all trees that stand near a residence or other combustible structure, stand alone and present a hazard to gathering of humans or animals, are of great historical or esthetic value. Where large trees are clustered, we recommend the application of ROBBINS LIGHTNING PROTECTION SYSTEM to a selected few - consider first the tallest and largest, then the most prominent ones around the perimeter of the cluster.

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