An Industry-Wide Misunderstanding
The misunderstanding I see throughout the industry is the belief that applying properly rated cover-up equipment eliminates exposure from the energized conductor or part. Yes, properly rated cover-up equipment can provide temporary insulation for the qualified electrical worker, but it does not eliminate exposure. The application of rated cover-up on overhead conductors and devices does not allow one qualified electrical worker, working alone, to work within the minimum approach distance (MAD). Rated cover-up does not eliminate exposure and if any work is to be done within the MAD, two qualified electrical workers must be present even if rated cover-up is installed on all the exposed conductors and devices. OSHA 1910.269(l)(2) – “Minimum approach distances” – states:
“The employer shall ensure that no employee approaches or takes any conductive object closer to exposed energized parts than set forth in Table R-6 through Table R-10, unless:
(i) The employee is insulated from the energized part (insulating gloves or insulating gloves and sleeves worn in accordance with paragraph (l)(3) of this section are considered insulation of the employee only with regard to the energized part upon which work is being performed), or
(ii) The energized part is insulated from the employee and from any other conductive object at a different potential, or
(iii) The employee is insulated from any other exposed conductive object, as during live-line bare-hand work.”
Paragraph (ii) above provides the option of using rated cover-up discussed in this article, properly installed, to allow a qualified electrical worker to enter the MAD.
What OSHA 1910.269(l)(2) specifies is how one qualified electrical worker, by themselves, can enter the MAD. The qualified electrical worker can don rated gloves or rated gloves and sleeves, install rated cover-up or use the bare-hand work method. But, when the qualified electrical worker uses one of the options above and then enters the MAD, they cannot do any work. If the qualified electrical worker wants to perform any work within the MAD, they must refer to OSHA 1910.269(l)(1)(i) which states:
“Except as provided in paragraph (l)(1)(ii) of this section, at least two employees shall be present while the following types of work are being performed:
(A) Installation, removal, or repair of lines that are energized at more than 600 volts,
(B) Installation, removal, or repair of deenergized lines if an employee is exposed to contact with other parts energized at more than 600 volts,
(C) Installation, removal, or repair of equipment, such as transformers, capacitors, and regulators, if an employee is exposed to contact with parts energized at more than 600 volts,
(D) Work involving the use of mechanical equipment, other than insulated aerial lifts, near parts energized at more than 600 volts, and
(E) Other work that exposes an employee to electrical hazards greater than or equal to those posed by operations that are specifically listed in paragraphs (l)(1)(i)(A) through (l)(1)(i)(D) of this section.”
There are two key terms in A through E above – “more than 600 volts” and “exposed.” At 600 volts and below, one qualified worker can perform any type of energized work by themselves. Above 600 volts it will take one qualified worker to perform the task, and a second qualified worker present, to perform work within the MAD even with rated cover-up properly installed on all energized conductors and devices. The other term is “exposed,” which OSHA 1910.269 defines as “not isolated or guarded.”
OSHA does not consider rated cover-up to isolate or guard. So, all the cover-up in the world does not eliminate exposure, and it takes two qualified workers to work within the MAD on conductors and devices energized above 600 volts.
Question: Can one qualified electrical worker, by themselves, work within the MAD if all the energized conductors are covered with rated cover-up before the worker enters the MAD?
Answer: No. If the qualified electrical worker is to perform any work listed in OSHA 1910.269(l)(1)(i)(A), (B), (C), (D) or (E) within the MAD, two qualified electrical workers are to be present, even if all the energized lines and equipment are covered with rated cover-up.
Question: A single-phase, energized overhead conductor located on the end of a crossarm has been properly covered, on both sides of the arm, with rated cover-up. Can one qualified electrical worker now, by themselves using the rubber glove work method, replace a cutout on a crossarm within the MAD of the covered conductor?
Answer: No. To replace the cutout the qualified worker will be working within the MAD and properly installed rated cover-up does not eliminate exposure. Two qualified electrical workers must be present to complete this job.
Cover-up is used to prevent qualified electrical workers from accidental brush contact with energized conductors and devices. At no time should workers purposely contact cover-up installed on energized conductors and devices unless they have donned rated insulated gloves and are using the rubber glove work method. This article does not cover the option of the use of cover-up and rated rubber gloves, or rated rubber gloves and sleeves.
Reach and Extended Reach
If rated cover-up is to be installed or removed using the rubber glove work method, two qualified electrical workers must be present at the work site as the worker installs or removes the rated cover-up. The qualified electrical worker installing and removing the cover-up must first don rated rubber gloves before entering the reach and extended reach area of the MAD. Then, using the rubber glove work method, they can enter the MAD and install or remove the cover-up.
“Reach and extended reach” is a description of the distance a qualified electrical worker must keep from an energized conductor until they have donned rated rubber gloves. In other words, if the conductors are energized at 13.2 kV phase to phase, the MAD is 2 feet 3 inches (per the 2007 NESC and the 2009 IEEE 516) and the worker’s arm reach is 3 feet, the worker must position their body 5 feet 3 inches (2 feet 3 inches + 3 feet = 5 feet 3 inches) from the energized conductor or device until they have donned rated rubber gloves. After they have donned rated rubber gloves, the qualified electrical worker can enter the MAD, but again cannot do any work within the MAD unless a second qualified electrical worker is at the job site and acting as a safety watch.
If rated cover-up is to be installed or removed using the hot stick work method, the worker must install and remove the cover-up – with hot sticks of proper length – from a working position where they will not enter the MAD. The reach and extended reach do not apply if the qualified electrical worker is using the hot stick work method and is actively hot-sticking. However, as soon as the qualified electrical worker is not actively hot-sticking, they must position themselves where they are not within the reach and extended reach of any energized conductors or devices that are not covered with rated cover-up.
Proper installation of rated cover-up requires the qualified worker to work from the outside in, meaning as the qualified worker approaches the nearest energized phase or device, it must be covered first. Then, as the worker moves inward toward the other energized phases or devices, the qualified worker will cover the next closest phase or device, until all energized conductors and devices in the immediate work area are properly covered. After the worker has completed their task and begins to exit the work area, the cover-up must be removed in the exact reverse order.
Another error often made in the industry is not installing enough rated cover-up. Both plastic guards and insulating line hose come in lengths of 3 to 6 feet. So, when two 4-foot pieces of plastic guard or line hose are installed – one 4-foot piece on each side of the insulator and an insulator cover – a total of 8 feet of the energized conductor is covered. That does not provide for 8 feet of clear working area for the qualified worker. At the end of each piece of cover-up is an exposed energized conductor, requiring the worker to stay the MAD from the ends of the cover-up.
Example: Qualified electrical workers install an insulator cover and two 4-foot, Class 2 plastic guards on either side of a crossarm of a 12.5-kV energized phase conductor. With the MAD equaling 2 feet 3 inches up to 15 kV, the workers must stay at least 2 feet 3 inches from either end of the cover-up, allowing only 3 feet 6 inches of clear working space as shown in Diagram A.
In addition, the qualified electrical worker needs to remember the reach and extended reach requirement. The worker must position themselves where they cannot reach into the MAD, which in this case begins at the end of the installed cover-up.
If a qualified electrical worker wants to install a cutout on the arm in Diagram A above, it will be necessary to install at least two additional pieces of 4-foot cover on the center phase. A second qualified worker will be required as a safety watch for the worker installing the cutout even with the use of rated cover-up since work is to be performed within the MAD.
Testing, Inspection and Maintenance
Cover-up equipment with phase-to-phase voltage ratings from ASTM Class 00 (600 V) to Class 6 (72.5 kV) is available for multiple applications. It also comes in a number of colors from standard orange to yellow, black, brown and clear. The manufacturing specifications, acceptance testing and in-service testing of this equipment are covered under ASTM standards, including:
• F712: Standard Test Methods and Specifications for Electrically Insulating Plastic Guard Equipment for Protection of Workers
• F479: Standard Specification for In-Service Care of Insulating Blankets
• F478: Standard Specification for In-Service Care of Insulating Line Hose and Covers
• F1742: Standard Specification for PVC Insulating Sheeting
• D1048: Standard Specification for Rubber Insulating Blankets
• D1049: Standard Specification for Rubber Insulating Covers
• D1050: Standard Specification for Rubber Insulating Line Hose
Inspection, maintenance, in-service testing and storage of cover-up equipment are integral parts of the overall application and use of this equipment. The industry has standards for in-service care and testing of insulating line hose and covers as well as insulating blankets, but no standard exists for in-service care and testing of plastic guards and covers. Plastic guards and covers must be inspected before each use to ensure they do not have cracks, deep scratches or gouges in the material. An approved wiping cloth must be used to remove any dirt or contaminates.
When it comes to plastic guards and covers, there is no approved method of repairing these devices. If the plastic guard or cover is cracked, loses its gloss, or is deeply scratched or gouged, it must be replaced. If an end of an insulated line hose is damaged, the damaged end can be cut off, allowing the good portion of the insulated line hose to be used.
Insulating blankets and insulating line hose and covers must also be thoroughly inspected daily before use for holes, embedded wires, rips or tears, ozone cutting, UV checking and signs of chemical deterioration. They must also be taken out of service and electrically tested.
The Importance of Voltage Ratings
When cover-up equipment is used in a work location where there is a phase-to-phase exposure to the qualified worker, the cover-up equipment must be rated for the phase-to-phase voltage. The voltage ratings of two pieces of cover-up equipment cannot be added together to get a total protective voltage rating. Example: The use of a Class 3 (26.5 kV use rating) cover-up on the outside phase and a Class 3 cover-up on the center phase of a 35 kV overhead line does not provide 53 kV (26.5 kV x 2 = 53 kV) of protection. Only Class 4 rated cover-up (36 kV use rating) can be used on a 35 kV phase-to-phase exposure. Also, two Class 2 (17 kV use rating) insulating blankets cannot be laid one on top of the other to provide a resultant rating of 34 kV; only one Class 4 insulating blanket can be used on a 35 kV system.
About the Author: Brian Erga, president of ESCI Inc., has more than 36 years of electric utility expertise and holds a BSEE degree. An expert on safety practices and work methods related to the electric utility industry, he is a member of IEEE/ESMO, NSC, NFPA and ASTM F18, and a member of NESC Subcommittee 8, responsible for NESC Part 4 “Rules for the Operation of Electric Lines.”