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In the same way building owners should have a plan in place for natural disasters, owners of outdoor equipment need to consider how a lightning strike can impact their assets.
Lightning strikes can cause serious damage to the equipment you have invested in and their sensitive electronics. Doing an initial risk assessment - which includes knowing your potential lightning risk will allow you, as a business owner, to decide whether or not you should invest in a proper lightning protection system (LPS), or if it is reasonable to take fewer precautions given your geography, and regional details.
It's likely that you, or someone you know, knows someone that has been affected by lightning. On average, lighting strikes cause over $15 million in losses of industrial/manufacturing facilities and equipment every year. There are also an average of 300 injuries and 26 fatal lightning strikes in the U.S. every year.
Striking Facts About Lightning
Before we explore ways to protect your equipment, let's discuss some lightning basics:
light·ning /'litniNG/
noun
The occurrence of a natural electrical discharge of very short duration and high voltage between a cloud and the ground or within a cloud, accompanied by a bright flash and typically thunder.
Most lightning bolts or strikes originate in cumulonimbus clouds (those are the big puffy white ones that have a tall column) and terminate on the ground. These are called cloud-to-ground lightning (CG) which are most common and result in 69% of all lightning events. There is also ground-to-cloud lightning (GC) and cloud-to-cloud lightning (CC). We'll be focusing on CG lightning since this type is the most dangerous and destructive to you and your property, namely your truck scale.
Now that we know the basics, here are a few “striking" lightning facts (just in case you're the next contestant on Jeopardy):
- When lightning strikes a tree, it travels just below the bark. This layer is filled with sap and water which becomes superheated and… POW! The bark is blasted off and the wood is splintered.
- Don't fool yourself. Nowhere outside is completely safe from lightning.
- A lightning strike can inflict serious bodily harm. Injuries can range anywhere from a mild burn on your body to damage to your brain to death. *Personal note from your author: My Aunt was 12 years old when she was struck by lightning walking home from school. The resulting strike blew out her eardrum and she's suffered with total hearing loss in her right ear ever since.
- Although the intensity of a lightning bolt makes it appear thick, the actual width of a lightning bolt is about as wide as a thumb. The small channel is so intense, temperatures can reach 30,000 degrees C. Five times hotter than the surface of the sun. Talk about sunburn.
What can lightning do if it strikes your scale?
“Hey Joe! All of that is well and good. But what about my truck scale?"
Okay, okay! Truck scales are built to withstand all types of use and abuse. The daily demands put on a truck scale are second-to-none, they're built to take it. They're tough and seemingly indestructible. But… (there's always a but,) they are at the end of the day huge metal bodies. In the event of a lightning strike, lightning will use any available conductor to find a path to the ground including electrical lines, phone, cable, computers, water pipes, or even a large metal conductor designed to weigh trucks!
So, what kind is the impact of lightning hitting a truck scale?
Simple answer? Plenty. Lightning can damage any part of a truck scale including load cells, junction boxes, cabling and indicators. Many times causing complete system failure.
More specifically, lightning can create any number of issues including:
- Fried wiring
- Power surges
- Voltage sags
- Calibration fluctuations
These all result in downtime, and nobody has time for that!
How many lighting strikes does it take to knock your truck scale out of commission? If you answered ONE you are correct! Your truck scale may as well have a big “STRIKE ME" sign on it because it's a magnet for lightning strikes.
Something to keep in mind. A lightning strike doesn't have to be a direct hit. Lightning can strike the ground near your scale and be just as damaging as it seeks a path to discharge. This is known as a side-flash and can cause lightning damage to your equipment!
When Is Lightning Protection Required?
There are a number of factors that determine the specific risk of a lightning strike at your truck scale location. Certain geographic locations have a higher number of annual lightning strikes than other areas (for example, Southern Louisiana has many more strikes every year than Northern Nevada). Some areas have fewer strikes each year, but when there is a thunderstorm, there tends to be a high number of strikes, a factor called Lightning Flash Density. Other factors include materials of the equipment, equipment corrosion, the implementation of a zone of protection, and the height and size of the equipment.
To better understand your specific vulnerability, Annex L of the NFPA 780 Standard has a risk assessment you can apply to your equipment. If you register with NFPA, you can view the manual for free.
What can you do to protect your truck scale from a lightning strike?
Unless you have a serious connection with someone “up there", there is nothing you can do to prevent lightning or a lightning strike. But there are steps you can take to protect your investment from a lightning strike.
1. Load cells with lightning protection
A CPD-M Digital load cell has a stainless steel housing that is hermetically sealed (IP69) and impervious to water ingress. They have built-in, fast acting protection devices (transectors) to guard against damage from surge voltage and lightning events. These load cells are installed on top of non-metallic isolation discs to prevent transient voltage from being transferred through the cell body. They communicate on an RS-485 serial communication string which has been 99% resistant to any lightning or surges. The corresponding warranty even says so!
Hydraulic load cells are also a type of technology, though very old technology, that protect against lightning. In a hydraulic load cell the measured load is applied to a load platform that is attached to a piston, this piston sits in a closed chamber filled with fluid. When a load is applied the liquid is pressurized by the action of the piston pressing on the diaphragm. The change in liquid pressure is directly proportional to the force applied by the load. This liquid pressure then becomes readable by a gauge or secondary transducer.
2. Grounding systems:
Grounding is crucial for your truck scale. A good grounding system from a reputable manufacturer comes with professional installation and will include necessary shield testing and bypass cable routing to prevent issues in the case of a lightning strike. If you choose to forego a professional installation, an improper grounding system may cause you more problems than it's worth! Air terminals ( Usually copper alloy rods, also called lightning rods) are generally paired to down conductors (ground rods) and grounding electrode systems that create a low-resistance path to grounding as a “tip of the spear" system. This system of surge protection devices (SPDs) that can protect sensitive electronics from lightning flashes... but this class of strike termination devices certainly have their own NFPA standards that need to be met and while the concept is simple to understand, the installation of this style lightning protection system (LPS) needs to be handled by a professional (Who understands lightning protection codes, such as NFPA 780, UL 96a, and building codes more generally)
3. Warranty and service guarantees:
Truck scale manufacturers oftentimes offer warranties and repair services if lightning strikes your truck scale. Warranties differ between manufacturers so you need to know what is covered by your warranty. Does your truck scale warranty offer coverage for these things?
- The cost of labor to replace a part damaged by lightning strikes, lightning discharge or side flashes.
- The cost of the actual replacement part that was damaged by direct lightning strikes, lightning discharge or side flashes.
And perhaps the best warranty question to ask, "how long, from date of purchase, is my scale covered by a lightning strike, lightning discharge, or side flashes"?
NOTE: Many manufacturers and regional dealers will have specific installation requirements that you may need to be aware of to make sure you are in compliance with their standard for the installation of lightning protection systems so that your warrant is in full force.
4. Transient protection:
The function of transient protection is to react to sudden changes in voltage. This form of surge protection exists as a series of DC and AC protection methods in your scale house, indicator, junction box and load cells. Many truck scales systems come with some degree of transient protection where lightning may otherwise cause serious damage to sensitive electronics.
We've poked a little fun in this article, but lightning currents and lightning strikes are a very serious concern. Your truck scale is a huge investment and often times your cash register. Once out of commission it becomes nothing more than a big, expensive paperweight.
While the steps outlined above can't guarantee your truck scale won't get hit by lightning, they will reduce the likelihood of irreparable damage and expensive downtime.
Are you protected?
Using the information provided in this article, we would recommend you create a “lightning strike" checklist and see where your scale stands. For example: is there metal piping nearby, or other conductive materials that could act as lightning conductors in the next thunderstorm?
If you would like to learn more about lightning protection systems, reach out to the experts at B-TEK, we are always happy to help
You can also check out information from Underwriters Laboratories, National Fire Protection Association (NFPA), and the Lightning Protection Institute (LPI). Your local electricians union may also be a resource for professionals in your area who can implement a system designed within the National Electrical Code (NEC) and consider all safety and code requirements.
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