According to an AWWA study, more than 350 significant distribution system electric
shock incidents occur annually to water utility workers. A much larger number of
minor shock incidents occur each year, many of which go unreported.
Electric shock is a danger water utility workers face during the installation and repair of water pipes and meters. Water pipes are often used to ground electricity in homes. If there is a fault in the electric system, the pipe or meter can be energized with electricity. A severe or even fatal shock can occur if enough electricity is present in the pipe or meter.
Some utilities insulate the water service at the corporation stop or meter. Electrical insula— of water services has proven to be very effective in reducing the number of shock incidents dents. However, many uninsulated services remain. So what steps should utility workers take to avoid being shocked on the job?
Understand the Hazard
Electricity always -wants to return to its source to complete a continuous circuit. A typical circuit has two conductors: one that flows from a service panel to an appliance and one
that returns the current to the panel. A neutral wire and ground wire are both connected to electrical ground: the neutral wire completes the electric circuit by conducting current away from the plugged-in electrical device. The ground wire is a safety device that carries electric current away from a device when the circuit or plugged—in device malfunctions.
Grounding wires are connected to all outlets and metal boxes and then down to the earth by attaching it to either a metallic rod or a water pipe. The shock to utility workers occurs when they install or remove a water meter or cut through metallic pipes connected to a faulty system.
Because electricity may take multiple paths to ground, the worker may get shocked when first touching a pipe or service meter. A worker may not get shocked when removing a meter or pipe because it breaks the circuit, but he or she may be shocked when reinstalling that meter or service line because that action completes the ground circuit.
Use Proper Procedures and Safety Equipment
Every case will be a little different, but here are some general guidelines to consider when approaching meters or pipes that are part of a home’s or building’s ground system.
- Identify the composition of the service line to be worked on and that of nearby proper- ties. This will help determine the likelihood of a shock hazard, because metallic water lines allow an electrical current to travel from a neighboring property. The pipes most likely to act as an electrical conductor are ductile iron, copper, cast iron, steel, and galvanized.
- Voltage—rated rubber gloves with leather “glove keepers” worn over them provide the best protection for workers and should be •worn when inspecting, installing, or removing a meter, or when cutting and repairing a service line. Class 00 rubber electric-safety gloves are rated for maximum use voltage of 500 volts AC and protect against most common shock hazards associated with residential electrical systems. Consult with a voltage-rated glove manufacturer to determine the appropriate class of gloves for your utility’s situation. Both pairs of gloves should be inspected prior to use and need to be tested and recertified periodically.
- Using voltage-rated gloves, check for current with a clamp-on ampere meter. The presence of amperage indicates a potential electrical problem and shock hazard. If there
is evidence of an electrical problem, notify the building occupant and/or local power company so that they can determine the source and eliminate the hazard. Be aware that a zero reading does not guarantee safety, as the source of the current may not be constant (i.e., a garage door opener) and safety equipment should still be used.
- A voltage—rated jumper or bridging conductor can be used to maintain grounding or bonding capability of a pipe during repairs by connecting around it during the repair. Using voltage-rated gloves, use an emery cloth or another method to clean the pipe to bare metal. Connect the jumper, mainline side first, securely to the pipe. Jumpers with alligator clips should not be used. If current is present, the amp meter should be used to measure that current is passing through the jumper prior to removing the meter or cutting a service line. Because electricity can take multiple paths to ground, a jumper should not be used as the only protection, voltage—rated gloves should be worn during the repair. When removing the jumper, disconnect the customer side first. Voltage— rated jumpers must be inspected prior to use and need to be tested and recertified periodically.
- If a worker is shocked, he or she should seek immediate medical attention. Be aware that an electrical injury can Cause arrhythmia that can be fatal hours after contact.
Some local codes now prohibit the use of water pipe grounding, but many do not, so the practice and associated hazard are still widespread. Don’t take chances: follow these safety tips when working with metal pipe and meters!