A contractor who provided additional services outside the scope of the electrical trade gets a lawsuit for his troubles.
Some electrical contractors may go the extra mile to help their clients by broadening the scope of their services. However, taking on design responsibilities outside the borders of the electrical trade can bring with it legal liabilities and possibly lead to litigation down the line. As a contractor in California's Sacramento Valley learned, it can sometimes be more trouble than it's worth.
A large farming business in the rice growing region of Northern California included the operation of a grain dryer that augered rice to the top of a large machine before dropping it through long, wide, thin-screened columns heated by hot air. The dried rice was then augered out to a silo for storage. The flow rate of the rice was metered by a long, small-diameter “paddle wheel” at the bottom of the dryer. Occasionally the rice would jam in the dryer bays. To break it free, operators entered a small space through a door out of sight of the control room and inserted a hook-like device into the bottom through the metering slot while the paddle wheel and augers continued to turn. Operators also sampled the rice for dryness by lifting the auger's cover plates and dipping a paper cup into the channel.
One day a young worker who had attempted the loosening procedure was found unconscious with his hand drawn up into the paddle wheel and the other arm drawn into the open auger at floor level. The starters for the 1-hp motors associated with the paddle wheel and auger had tripped out on overload. As a result of his injuries, the worker lost the use of both arms. His employer's workman's compensation insurance, maintained by the farm, covered medical bills and provided a small disability pension as provided by law. However, his attorney wanted him to receive a more generous compensation for his life-affecting injuries and brought suit against the grain dryer manufacturer and the installing electrical contractor, both of which had liability insurance.
The worker's attorney asked me to testify to the installation's controls compliance with the NEC, the manufacturer's design of the controls, and the electrical contractor's installation of those controls.
Several operational issues arose during the investigation. Why was the machine running during the unclogging process? What training did the operators have regarding safety during troubleshooting of the process? Was there any way to turn off the machine to prevent such an accident? Would a safety disconnect switch have made a difference?
The motor control center (MCC) and its controls were located in a room that was out of sight of the dryer operations, partially to prevent rice dust from accumulating in the equipment. The motors and their disconnects were also located outside of the space. Although common sense would dictate that the machinery should be turned off while the paddle wheel were unclogged, the operator convincingly testified that workers couldn't effectively clear the rice jams unless it was running. This suggested that proper guarding of moving parts and an emergency shutdown “trip wire” were essential design considerations that couldn't be controlled by a safety power disconnect switch. Such trip wires were found to be common along auger and belt conveyors in the grain handling industry.
According to 430.102(B) of the NEC, safety disconnects for use during mechanical repair should be located in sight of the motor location and the driven machinery location at the bottom of the dryer. In this case one should have been located in the small enclosed access space. Such disconnects are often supplied by the manufacturer, not the electrical contractor. If a manufacturer fails to supply the disconnects, no one would argue that the electrical contractor is responsible for providing them. The more nebulous question is, Who is responsible for providing and locating the emergency shutdown “trip wire” and the control switches not specifically required by the NEC? The electrical contractor should be capable of designing systems that provide the power to machines in concert with the NEC. But should the contractor be expected to add controls to a complex machine that might interfere with the already researched and engineered implementation of that machine's design? Can the contractor assume that a machine has been researched and engineered for safety?
Clogging is a common problem in the grain dryer industry, but the “hay hook” clearing device used during operation was potentially hazardous. Additionally, the lack of a disconnect was a clear Code violation that implicated each defendant for liability. But which party was responsible for any “panic” shutdown controls? This would determine what percentage of the claim each party would pay. At first analysis this would seem the responsibility of the designer/manufacturer. Oddly, investigation revealed that it was the electrical contractor who had manufactured and provided the clog clearing tool and training for its use. Why would an electrical contractor do that?
As it turned out, this electrical contractor was also the factory authorized regional sales, service, and installation agent who provided startup support and operation training. Thus it was within his purview and responsibility, in concert with the manufacturer, to design and install machine modifications required for safe operation. Further, when the operators complained that it was awkward to sample the rice while holding up the auger cover plates, the electrical contractor provided and installed chains that could be used to hold the covers in the open position, without also providing interlock switches to shut down the auger.
The case ended in confidential settlements of undisclosed amounts, suggesting that the attorneys for both defendants recognized their clients' liability.
Farming is a known dangerous business where workers may be poorly educated, ill trained, and accustomed to taking risks. The “training” here didn't include a section for what to do if something went wrong during the unclogging process. Operators had discovered that if they stopped the machine to unclog it, it would be clogged again when they returned from the restart. Users can be very inventive when it's their job to maintain production flow. Odds are even if it were provided, a safety disconnect switch or panic button wouldn't have been within reach of the plaintiff. This machine clearly called for a panic bar or trip wire along the length of the dryer. Further, a procedure that didn't require access to the moving auger was required for rice sampling. All these requirements were readily implemented after the accident.
It's important to analyze your client's needs and behaviors when installing electrical systems. Cases like this one make it clear why the NEC states that it's not a design guide nor an instruction manual. Remember, there's more to electrical work than merely meeting the Code requirements.
Crawford is a forensic electrical engineer in Sandpoint, Idaho.