Hubbell Power Systems Blog

Temporary protective ground sets are one of the most important pieces of personal protective equipment line workers use while performing de-energized and grounded line maintenance. To maintain the integrity of the ground sets while in service, Hubbell Power Systems recommends testing ground sets to ASTM F2249 at least once annually and performing a visual inspection before each use.

In many cases, a line worker is faced with several daily tasks which require them to use a single-point-of-contact voltage detector. With a variety of options on the market, knowing which type to use for a project can be challenging. Hubbell Power Systems' CHANCE® Tools brand offers a wide variety of voltage detectors. When using a voltage detector, it is critical to always use a proper length hotstick that complies with company and OSHA-mandated minimum approach distances (MAD). Rubber insulating gloves should never be used as the only form of PPE when using a voltage detector.

During line work, it is commonplace for lines to be de-energized and grounded for worker protection in the event there is a fault current, which could be due to a variety of issues. In this blog, we will look at some common misconceptions about temporary personal protective grounding.

To maintain worker safety while performing de-energized and grounded line maintenance, two important factors must be accomplished in the event of a fault:

1. The fault current must be cleared in the fastest available time
   
2. The current across the line worker must be limited to a safe level by creating an Equi-Potential Zone (EPZ)

CHANCE® Personal Protective Ground Sets are an important tool for lineworkers to use during de-energized line maintenance. The ground sets serve two purposes; one is to provide an Equi-Potential Zone (EPZ) minimizing current flow through a lineworker and the second is enabling the clearing of the fault in the fastest available time. In order to make sure the personal protective ground sets will function properly during daily use, daily inspection and periodic testing must be performed.

What is Step and Touch Potential?

While performing energized or de-energized line work, there are many opportunities for a line worker to encounter differences in electrical potential. Opportunities could include working near bucket trucks, underground gear, overhead switches, or in substations. When a difference in potential occurs across a worker’s body, current begins to flow. This current flow can be very hazardous as it only takes 50 to 60mA to become possibly lethal. These differences in potential can be categorized as step and touch potential. Step potential is defined as a difference in electrical potential between a worker’s feet and touch potential can be between a worker’s hands or hands and feet.

Energized line maintenance is a popular option for working on power lines. Two common methods for hot work include rubber gloving and hotsticking. These two work methods will utilize both primary and secondary levels of protection from energized lines and equipment. Live line barehand is another work method for working on energized lines and equipment but will not be discussed in this blog. This blog will discuss the differences between primary and secondary protection while using the rubber gloving or hotsticking work methods.

There are few jobs that are more dangerous than that of a utility lineworker. A commitment to safety is of utmost importance, both in the design of tools and equipment and in the training given to understand how to use them properly.

Hard Plastic vs. Rubber Cover-Up Equipment

Deciding which cover-up equipment is best for the job depends on several factors, including the system voltage, types of energized equipment, and work methods (rubber gloving vs. hotsticking).

Insulating rubber blankets for energized line maintenance come in a variety of sizes, classes and types. Each Class of insulating blankets has its own maximum use and testing voltages, as described in ASTM D1048 (see Table 1). The higher the class rating, the higher maximum the voltage rating is for the insulating blanket.