Smith-Root Barrier Safety

Smith-Root barrier systems are safe to operate when done so in accordance with the design criteria specified for each unique situation. There are two areas of concern for electrical safety. Out of the water, the Smith-Root electrical barrier systems are designed with careful attention to all national safety codes. Nevertheless we require them to be fenced and to carry warning signs. In the water, the water acts as a conductor in the circuit. The voltage is dissipated over the length of the field so that the voltage gradient over any small length of the field is much less than the total voltage applied.

Smith-Root barrier and behavioral guidance systems are designed to be non-lethal and to use only low-frequency pulsed DC to create electric fields. Humans are three times more likely to be harmed by alternating current (AC) than by DC current, and it has been shown repeatedly in the scientific literature that use of AC can injure fish. Pulse frequency (especially) and duration and current can all contribute to potential damage, thus Smith-Root typically sets these values well below the electrocution threshold of a typical ground fault interrupter. Pulse frequencies for barriers are much lower than those used in traditional electrofishing. Our interest for most barriers is in changing fish behavior, not achieving galvanotaxis or anesthesia.

Vessels can safely pass through our electrical fields. Metal-hulled vessels create local short-circuits (requiring longer fields to ensure that fish do not find a pathway through); there are no potential differences within a hull. Hulls of insulating materials merely distort the field by displacing the conductive water. As occurs in the Chicago Sanitary and Ship Canal multiple times per hour, metal-hulled barges traverse our series of electric barriers for Asian carp control with no effects to vessels or occupants.

Safety Details

The danger of receiving electric shock is increased when working around water. To receive an electrical shock, a person must be part of a closed circuit in which current can flow through them. Just how badly a person is affected by electric shock depends on the following:

1. The path the current takes through the body. The chest and head are the most vulnerable areas. All personnel should wear rubber lineman's gloves and a safety helmet.
2. The time spent in the circuit. The sooner the circuit is interrupted the better.
3. The person's age, size, and health. The greatest danger is to a person with a prior heart ailment.
4. The amount of current that flows through the body. When the body is submerged in water this becomes a complex situation involving many variables and very little data is available.
5. The type of current, AC or DC. Humans are three times more likely to be electrocuted by AC current than by DC. For this reason Smith-Root barrier and guidance systems only use DC current.
6. Whether the current flow is continuous or pulsed. UL Laboratories found that short pulses are much less likely to be lethal, see figure 12 below. Smith- Root barrier and guidance systems use a pulse of much shorter duration than that of a typical Ground Fault Interrupter Circuit.