As the angle of the sun lowers, it becomes a little more difficult for you to keep one eye on your spotter, and one on the darkening trench before you, then it happens: there is a bright flash out of the corner of your eye, the loud ‘crack’ of a high voltage arc, followed by a heavy transformer type hum, and then quiet. One of the main hydro line breakers has been tripped, but it is on a time delay, and about to automatically reset.  Knowing that this is a possibility, you stay put, waving to the others to stay away, and advising them to call the local hydro company.  They arrive promptly and disable the automatic reset, allowing you to safely disembark from your equipment.

As with any job, efficiency and safety are crucial. It’s also important to recognize when the number of factors is stacking up against you. Weather conditions, the time of day, aboveground and belowground hazards, time pressures, all of these and others may all begin to stack up, until there is possibly just one too many. 

Contact with electricity continues to be a significant cause of fatalities within the construction industry. The US Bureau of Statistics and the Center for Construction Research and Training monitors injuries and fatalities that occur each year, and the number of overall fatalities within the construction industry in the U.S. is considered to be relatively high when compared to other countries. Of the deaths that are related to electrocution, a significant portion is related to equipment contacting high voltage lines.  Electrocution continues to be the cause of one in five deaths in the construction industry, and a good number of these are preventable. 

Some rules that have been designed to help improve safety include minimum required clearances from power lines. These are stipulated by the U.S. Occupational Safety and Health Administration.

Determine the voltages of the lines you are working in close proximity with (check the pole or poles for a voltage label; if there is none, call the local utility) and have a trained spotter assist you in maintaining these minimum required distances. 

If, for example, the spotter becomes distracted by having to clear people out of the area, stop work until his full attention is back on the job. Ensure that both operator and spotter understand, and are working from, the same set of hand signals. Review them prior to commencing work, if necessary. 

The spotter should wear visible clothing and be positioned in a way that they are readily visible to the operator. Be aware of the risk of arc flash to overhead lines. Absolute contact my not be necessary under some conditions, such as high humidity, or a damp earth. Both of these factors make your machine a more attractive ground path for high voltage. 

Respect the minimum distances, as these have been determined by taking environmental factors into consideration. If work is such that the minimum distances cannot be observed, arrange for the local utility to shut down the power or have the utility add wire insulators in the required locations.

If the power is shut down, the utility will clamp on an auxiliary ground wire which serves two purposes: first, it drains any residual charge, if present, and ensures that no ‘stray’ voltages can be induced into the line; and secondly, it provides an important visual confirmation that the power is off and the line is de-energized.