What happens when lightning strikes a piece of heavy equipment, such as a backhoe?
Electrically speaking, currents are carried mostly on the outside of conducting objects. The outer surface carries most of the electricity. The conditions inside the steel cab can be likened to protection by a partial Faraday Cage.
The hazard depends on the conditions. For example, is the cab dry or wet? If the cab is made of fiberglass (a poor conductor) or if it is open, the “skin effect” principle described above may not apply.
Backhoes, bulldozers, loaders, graders, scrapers, mowers, etc. which have enclosed cabs (ROPS) are generally safe during nearby electrical storms. Shut down the equipment, close the doors, and sit with your hands in lap to wait out the storm. Do not touch anything that may be connected to the outside. During close lightning, never attempt to step off the equipment to the ground. Should you do so, you establish a “dual pathway to the ground,” which creates a very dangerous “step voltage” and “touch voltage” situation. In their attempt to equalize themselves, the lightning voltages may go right through you.
Smaller equipment without ROPS is not safe during electrical storms. Riding mowers, gold cards, utility wagons, compactors, and other equipment are examples. Rubber tires do not provide protection from lightning. Should an electrical storm approach while you are using this type of equipment, abandon the machine and get into a safe substantial shelter.
A person who has been struck by lightning will not retain an electrical charge. Call 911 or send for help. Apply First Aid if you are qualified to do so.
© 2008 The Hartford Loss Control Department, All Rights Reserved. CFLC 84 Backing Heavy Equipment Safely. The information provided in these materials is intended to be general and advisory in nature. It shall not be considered legal advice. The Hartford does not warrant that the implementation of any view or recommendation contained herein will: (i) result in the elimination of any unsafe conditions at your business locations or with respect to your business operations; or (ii) will be an appropriate legal or business practice. The Hartford assumes no responsibility for the control or correction of hazards or legal compliance with respect to your business practices, and the views and recommendations contained herein shall not constitute our undertaking, on your behalf or for the benefit of others, to determine or warrant that your business premises, locations or operations are safe or healthful, or are in compliance with any law, rule or regulation. Readers seeking to resolve specific safety, legal or business issues or concerns related to the information provided in these materials should consult their safety consultant, attorney or business advisors.