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A conductor cable running up a large oak beside a home

Lightning protectionProtect

Lightning protection for high-value trees.

A conductor system gives a strike a preferred path to ground, so it is less likely to damage the tree, flash to a nearby building or throw debris.

Request a lightning assessmentAdd it to a Master Plan
Standard
ANSI A300 Part 4
Candidates
Trees within 10 ft of a structure
Conductors
Copper, bronze or stainless
First
A basic (Level 2) risk assessment
Request a lightning assessment

What we see in the field

Tall, isolated, and close to the building.

Strike risk rises with height and isolation. The trees we look at: trees within 10 ft of a structure, trees of historical interest or unusual value, tall trees in parks and recreation areas, and isolated trees on open ground or a golf course. In published susceptibility tables, oak rates high, pine and maple moderate.

A system is for a tree in sound health that is worth protecting. A tree that fails its risk assessment, or is in poor health, does not get one.

A braided conductor cable running up the trunk of a large oak
In the fieldA braided copper conductor on a large oak trunk.

How we do it

Assess, specify, install, maintain.

  1. Assess the tree

    Height, isolation, value, distance to structures, and a Level 2 risk assessment of its health and structure.

  2. Specify the system

    Primary conductor top to ground, branch conductors to major leaders, bonding to any metal in the tree, and grounding.

  3. Install to A300 Part 4

    Components made for tree systems. Standoffs into sound wood. Connectors with 1 to 1.5 in of overlap; clamp-type within 3 ft of the soil.

  4. Bond and check

    Support hardware bonded before the system is called complete.

  5. Inspect over time

    Conductors can last over 50 years, but the system is checked and extended as the tree grows.

What is included

What a lightning system covers.

  • Assessment first

    A basic (Level 2) tree risk assessment, so the system goes only on a tree in sound health.

  • A specified system

    An ISA Certified Arborist specifies the system for the tree, its position and the structures around it.

  • Air terminal and conductors

    A manufactured blunt terminal preferred. Copper conductors of at least 0.022 sq in total cross-section, top to ground, with branch conductors as needed.

  • Bonding

    Every metal object in the tree, such as a support cable, is bonded to the system. Copper never touches galvanized steel.

  • Grounding

    Ground rods at least 1/2 in by 8 ft (5/8 in preferred in hard soil), or a copper ground plate, clamped with at least two bolts.

  • Periodic inspection

    Deteriorated parts replaced, overgrown fasteners reset, and the system extended upward as the tree grows.

Next stepRequest a lightning assessmentorbuild it into a 10-year Master Plan

Standards we work to

Built to the national tree standard.

Our lines

  • Not installed on a tree that fails its risk assessment or is in poor health.
  • No aluminum or unclad steel in the working system.
  • Support hardware in the tree is bonded before the system is called complete.
  • A protected tree is not a safe place to stand in a storm. The system protects the tree and nearby structures, not people.
  • It does not protect irrigation controllers, lighting, cameras, well pumps or electronics in buildings.
ANSI A300 Part 4, Lightning Protection Systems

The standard for tree lightning systems: materials, conductors, connectors, grounding.

NFPA 780

The national lightning protection standard, cited with A300 Part 4 for trees within 10 ft of a structure.

ISA Arborist News CEU (2015)

Tree Lightning Protection Systems, part one: the reference behind our materials and bonding rules.

Sources: Ptolemy Lightning Protection spec; Smiley, Graham and Cullen, Tree Lightning Protection Systems (part one), ISA Arborist News, 2015; ANSI A300 Part 4; NFPA 780.

On the job

Lightning protection, in the field.

A ladder and conductor on a large oak beside a home.
A ladder and conductor on a large oak beside a home.
Large trees along a golf cart path, on the open ground where strike risk rises.
Large trees along a golf cart path, on the open ground where strike risk rises.

Strike damage

What a lightning strike leaves behind.

Field condition first. On a palm, the trunk splits along its length. On an oak, a long strip of bark is blown off on the way to the ground. Damage inside the trunk and roots can be worse than what shows.

A cabbage palm trunk split open near the base after a lightning strike
A cabbage palm after a strike. The trunk split lengthwise and the fibers are torn open near the base.
An oak with a long strip of dead bark running down the trunk to the ground
An oak after a strike. The damage runs down the trunk toward the ground.
Looking up a cabbage palm trunk at a torn strip running toward the crown
The same palm, looking up. The torn strip runs toward the crown. On a palm, decline can follow weeks to months after the strike.
Close view of shredded inner bark on a lightning-struck oak
The same oak up close. Bark blown off and the wood beneath shredded. Struck trees also draw bark beetles, so we keep watching them.

Who it is for

Written for the people who answer for the trees.

Inside a plan

Lightning protection is a Protect service.

MonitorManageProtect

On a Palm and Tree Master Plan, lightning protection is added per job and priced by proposal. The protected trees are flagged in our GIS inventory, so their inspections stay on the calendar.

The Palm and Tree Master PlanThe Health Program

Questions

Questions managers and boards ask.

Still have a question? Call (239) 467-0142 or send a request.

Which trees should have lightning protection?
Trees within 10 ft of a structure, trees of historical interest or unusual value, tall trees in parks and recreation areas, and isolated trees on open ground or a golf course. The tree must be in sound health; a tree in poor health or with unacceptable risk does not get a system.
Does it make it safe to stand under the tree in a storm?
No. A protected tree is not a safe place in a storm, and the system does not prevent step voltage at ground level. It protects the tree and nearby structures.
How long does a system last?
Copper conductors can last over 50 years. The system is still inspected periodically: deteriorated parts replaced, overgrown fasteners reset, and the system extended upward as the tree grows.
Our tree already has a support cable. Is that a problem?
It has to be bonded to the lightning system. An unbonded support cable is the most common cause of sideflash inside a protected tree, and copper must never touch the galvanized cable directly.

Next step

Protect the tree you can never replace.

We assess the tree first, then specify a system to the national standard.

Request a lightning assessmentAdd it to a Master Plan
Or start with a property assessmentCall (239) 467-0142