By: Roger Farmer, Contributor
The ASTM F2321 Standard Specification for Flexible and Rigid Insulated Temporary By-Pass Jumpers was revised and updated in March 2023. This article takes a closer look at some key points found in this important standard, the intended use and purpose of temporary By-Pass jumpers, and how to select the right components that make up a by-pass jumper set.
Scope of the ASTM F2321 Standard
1.1 “These specifications cover the manufacture and testing of flexible insulated temporary By-Pass jumpers (By-Pass jumpers) used on energized power lines and equipment.”
1.2 “It is common practice for the user of this protective equipment to prepare complete instructions and safety regulations to govern in detail the correct and safe use of such equipment.”
1.3 “The use and maintenance of this equipment are beyond the scope of these specifications.”
The purpose, significance and use for by-pass jumpers are also found in this standard:
4.2 “By-Pass jumpers are devices designed and used to keep electrical circuits continuous (electrically bridged) for short periods of time at work locations when conductors or equipment may otherwise be opened or made discontinuous during work operations. By-Pass jumpers are insulated to temporarily protect personnel from brush or accidental contact only.” Section 4.2 also goes on to add: “Warning – Portions of these devices (clamps and ferrules) are not insulated and offer no protection from accidental contact”.
The Basic Components of By-Pass Jumper Sets
Insulated by-pass jumper sets consist of three basic components: a length of insulated cable, one pair of ferrules and one pair of clamps. The right selection for each component is important but the selection of the style of clamps is critical, as it is the part that will ultimately be making direct contact with the energized conductor.
Insulated Cable: The selection of the insulated cable depends on the continuous current and the system voltage. TABLE 4 in the ASTM F2321 is designed to help the user determine exactly what cable is required for their specific needs.
Ferrules: Ferrules are crimped onto the insulated cable conductor and the connection necessary to join the conductor and clamps together. The ferrule will be determined by the conductor size of the insulated cable selected. Two styles of ferrules are available and are designated as “shrouded” and “unshrouded”. “Unshrouded” ferrules are crimped on the conductor only. “Shrouded“ ferrules are crimped on the conductor and the insulation portion of the cable.
Clamps: As noted earlier, the clamps are the components that will ultimately make direct contact with energized conductors. By-Pass jumper clamps are available in two styles.
Style 1: Clamps equipped with handles for installation on energized conductors. Note that this installation by hand must be done wearing appropriately rated PPE for the system voltage.
Rubber insulating gloves must meet the ASTM requirements below:
Style 2: Clamps equipped with provisions for installation on energized conductors with live line tools (the selection and use of these clamps are beyond the discussion of this article).
The major issue with all jumper clamps and handles is they may become loose. Reasons that contribute to this natural phenomenon are line vibration, atmospheric conditions (wind, temperature variations, etc.), and the jumpers left on lines for extended periods of time. Loose jumper clamps have been known to cause fires and power outages. Use of wrenches or pliers to secure traditional clamps tighter on conductors is common practice, but these clamps still may become loose. It has been reported that many users will periodically inspect and retighten already installed jumper sets for the duration of the project.
What jumper clamp or handle is best for your needs will depend on many factors. A very common type of By-Pass clamp is Style 1 (Jumper Handles) as it’s easy to install and often more effective and safer when in use. No real solution has been introduced to the market to solve these issues until now. The newest innovation in jumper handles is now available to prevent these types of jumpers from becoming loose. These new spring-loaded jumper clamps from PENTA ESP will assist in keeping jumper handles tightly secured even under the most adverse conditions.
PENTA’s new spring-loaded clear jumper clamp Improves clamping on the conductor. Image courtesy of PENTA.
Other Considerations When Selecting Jumper Handles
When selecting jumper handles, the preference is given to clear jumper handles. Inspection of the ferrule/cable connection is made much easier when using clear jumper handles. Another thought when selecting these jumper handles, is to look for additional hand gripping features. Anything that improves grip in the shape or design will make the application of these jumpers a better experience for line workers assigned with this task. Linemen must use and wear appropriately rated equipment per their employer’s best safety practices.
Recommendations
It is important but not that in the scope of the ASTM F2321 Standard: “The use and maintenance of this equipment are beyond the scope of these specifications.”
Each employer should perform a hazard assessment (i.e. must know the system voltage and the continuous current) when selecting cable and ferrules for applications that require by-pass jumpers and develop work practices. Employers should emphasize visual inspection prior and after each use and establish storage conditions when By-Pass jumpers are not in use. Close attention should be paid to the cables’ connection to the clamps and overall condition of the insulated cable. Sanctioned authorities have not yet addressed the concern of an “in use” standard as our market has already generally accepted care and maintenance practices.
However, we strongly recommend that a recertification process is established and followed by the users. North American Independent Laboratories (NAIL) for Protective Equipment Testing accredited facilities (https://nail4pet.org) can be of great assistance with all these needs.
Remember that by ASTM F2321, even when tested and functioning as intended, by-pass jumpers are considered “insulated to temporarily protect personnel from brush or accidental contact only.”
Conclusions
In a market that still lacks comprehensive regulation and consistent innovation, PENTA ESP’s newly developed spring-loaded jumper handle offers a much-needed solution to the persistent problem of loose connections in by-pass jumper clamps. These loose connections can lead to dangerous outcomes, including power outages and fires, making the adoption of more reliable technologies essential.
As the electrical industry continues to evolve, it is imperative that manufacturers, regulatory bodies, and end users work together to establish more rigorous care and maintenance standards. The current gap in regulations leaves companies and workers vulnerable to safety risks, underscoring the need for increased oversight and standardized maintenance practices.
In the meantime, we strongly recommend that users follow best practices for selecting, assembling, and maintaining By-Pass jumpers. Regular inspections, proper storage, and adherence to safety protocols are crucial to ensuring that jumper sets remain in optimal condition and safe for use. Additionally, companies should establish recertification processes to ensure that equipment meets safety standards throughout its lifecycle.
The PENTA ESP spring-loaded jumper clamp is a step in the right direction, offering improved performance and safety in even the most adverse conditions. By adopting these innovations and implementing stricter safety measures, companies can better protect their workers and maintain the integrity of their electrical systems.
Ultimately, it is up to the key influencers in this industry – manufacturers, safety professionals, and regulatory authorities—to push for more stringent regulations and safer practices. By doing so, we can reduce risks, improve operational safety, and create a safer working environment for all line workers.
This type of product must be used by authorized and trained professional line workers only.
About the Contributor
PENTA is an indispensable partner for linemen, maintenance technicians and electricians who work on electricity generation, transmission and distribution networks throughout the world. Learn more at: https://www.pentaesp.com/gb_us/penta-us/