Grounding Essentials

By Alan Drew, T&D World Magazine, September 2001, Volume 53, Number 10 Safety in line construction continues to be a big concern. No lineworker knowingly would contact an energized line without the proper safety equipment. However, instances show a need for continuing education into the proper application of personal-protective grounding (PPG).

PPG Importance

Many of the tasks lineworkers perform—such as climbing, setting poles, stringing wire and installing equipment—have remained relatively unchanged, while some of the equipment certainly has improved. Most of these modifications speed up the task without changing the fundamental installation method. However, PPG changes have increased the time it takes to properly install the devices, which can be difficult for many lineworkers to accept.

Today’s lineworker must have an in-depth knowledge of issues such as fault current, sources of electric energy, ground sources, testing, specific installation procedures and equipotential zones. It may take a new lineworker months, or even years, to fully understand the concepts and application of PPG.

The main objectives of PPG today remain the same for all applications. These objectives provide the best opportunity to avoid injury to the lineworker: limit the amount of current flow and voltage drop across the lineworker’s body; minimize the time that the current could flow through the lineworker’s body.

Human Body Reactions

Engineers have conducted considerable research relating to the human body’s reaction to various amounts of current flow and voltage drop. Many variables involving the human body, including body weight and skin moisture, contribute to the way each person responds to a current flow and a voltage drop. This makes it extremely difficult to determine any safe standard for all the differing scenarios.

However, research has established that as the levels of current flow increase and the duration of time that the current flow increases, damage to body tissues and organs increases. It is extremely important always to strive to minimize current flow, voltage drop and the time duration of the current flow.

Minimizing Resistance

The grounding components and their installation are critical to meeting the two objectives. The grounding components must have the ability to carry the available fault current until the protective equipment responds.

This requires lineworkers to fully understand the importance of making low-resistance connections of the grounding jumpers by cleaning the line conductors and clamps, plus providing a tight connection. Maintaining the grounding components in good condition and selecting the ground source with the lowest resistance possible are critical.

Accidents and Violations

Accident statistics directly related to the application of PPG are difficult to track on an industry-wide basis. Nevertheless, accidents continue to occur.

Discussions and feedback from supervisors and lineworkers confirm that violations of rules and procedures occur with frequency on certain crews. These violations happen in spite of all the hard lessons learned, regulations established and training conducted. In many cases, the degree of these violations is a reflection of the crew leader's ability to provide leadership to crewmembers. Some companies indicate that because they perform most of the work on energized lines, lineworkers are complacent with the application of personal-protective grounds. The majority of the violations occur in the following areas:

Failure to apply personal-protective grounds. Disappointingly, people still work on de-energized lines without installing personal protective grounds. In many cases, the lineworkers have decided to take a calculated risk, particularly on short-duration jobs.

Failure to test before applying the grounds. In spite of the OSHA requirement to test the line before applying grounds, many lineworkers have applied PPG to untested phase conductors. The lack of available test equipment attributes to this infraction.

Failure to use the proper grounding components. The use of an improper grounding clamp and a small conductor continues to occur. Hot-line clamps, not rated for fault current, and wire smaller than the OSHA required #2 AWG copper, are not proper grounding sets. The use of these materials shows a lack of understanding about fault current levels and the fault current rating of grounding components.

Failure to protect from all sources of potential energy. In some cases, lineworkers failed to consider all the potential sources of energy. This typically includes generator back feed, induction from adjacent lines and potential contact with existing lines. Depending upon the circumstances, there can be several potential sources of energy to consider.

Failure to follow proper installation procedures. Accidents continue to happen with lineworkers removing the ground end of the grounding jumpers before removing the line end. These accidents typically occur on transmission lines where induction from adjacent circuits is significant.

Failure to prove the cables are de-energized at the work site. This infraction typically occurs in underground systems. Because of incorrect mapping or cable tags, the wrong cables can be inadvertently isolated with cables at the work site that are still energized. Testing and grounding are essential work practices.

Self Assessment

Are any of the infractions above occurring at your company? It is prudent for companies to assess their safety program by focusing on the following elements:

Procedures, rules and standards. Most companies have rules and procedures for PPG. This fundamental element is effective as long as the rules and procedures meet current OSHA standards and have periodic employee reviews. Ask yourself these questions about your PPG program:

Do you have adequate updated rules and procedures?
Are your employees trained to understand them?
Do they always comply with them?
Are crew leaders and supervisors held accountable?
Do safety personnel and crew leaders have authority to take action to correct safety behavioral performance?

Training and certification.

Companies provide training on the application of personal-protective grounds. Refresher training certifies your lineworkers maintain competency in the application of PPG. Well-written grounding manuals with enhanced graphics makes excellent training material.

Grounding components.

Good PPG practices require maintenance of grounding components and regularly scheduled testing of grounding sets pay big dividends.

Although not required by OSHA, take the time to strip the trucks, stations, and tool rooms of personal-protective grounds and confirm their condition.

As lineworkers learn the new operating systems and construction standards, keeping attuned to advances in PPG tools and training is key to a safe workplace environment.

Alan Drew is the vice president for Northwest Lineman College. Drew began his career with Pacific Gas and Electric Co. in 1959 and advanced through the ranks from lineman to operations manager. He also worked as the general superintendent for Clallam County Public Utility District in Washington. He holds the BSEE degree and is a member of the IEEE.