Unique Issues

While implosive splicing technology provides a higher level of quality and performance than hydraulic compression, it does come with a unique set of complications. First is the issue of federal, state and local compliance. NU had to seek approval from the states involved in order to carry out the work. Then, in compliance with the Connecticut Fire Marshal's office and the Federal Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF), NU hired a licensed explosives expert to store and transport the implosive connectors and detonators. NU purchased an explosives magazine, which was inspected by the ATF and stored at the blasting contractor's approved storage property during the course of the project.

Then there was the noise. When the implosion splice is detonated, it creates a brief sound similar to a loud thunderclap, creating a momentary yet palpable overpressure in the air. Stakeholders were assured by the manufacturer that the sound levels would be within permissible state and federal guidelines, and the utility hired seismic and sound specialists to monitor the implosions.

Scope of the Project

After field testing the product at NU's training facility, the utility launched the project with a 12-month completion deadline. Quanta crews were responsible for installing the new connectors, replacing on average 6 to 12 connectors each day. To mitigate concerns regarding the noise, the utility established blasting criteria such as not “shooting” within 200 ft of a home or occupied building. Pickup trucks and vehicles were kept 150 ft away from the implosion area to help avoid potential overpressure damage. All workers, including the detonating crew, also were positioned 150 ft from the implosion. The only vehicle allowed inside the 150-ft radius was the insulated “barehand” bucket truck, which was often directly under the implosion. At such close range, the truck suffered several cracked windshields resulting from the blasts' overpressure.

During peak work months on the project, Quanta assigned 18 crew members, including two certified barehand crews conducting live-line work. The barehand work was typically performed from 105-ft double-elevator, six-wheel-drive bucket trucks. Due to the heights of many towers, NU used a barehand-certified truck crane with 178-ft reach.

Each connector replacement involved a two-man bucket, with two barehand-certified crew members in the bucket and a third member on safety watch. From the ground, a safety watch monitored aerial work, clearances and measurements of boom current leakage on the equipment. Additional crew members prepared the IMPLO connector sleeves for installation and operated the ground equipment. NU's supervisor from the Transmission Lines & Field Contract Services department led the project, along with several other personnel.

Challenge of Coordination

While maintaining good public relations can be a challenge with any major utility work, the implosive splice project took community outreach to a whole new level. An NU public liaison provided advance notice of the work to public officials, police departments, local fire marshals and newsrooms in each town before Quanta crews arrived. The utility also sent mailings and prerecorded phone messages to residences living near the rights-of-way, as well.

NU also gave presentations in many of the affected towns, so residents would know what to expect. The utility also made dozens of phone calls each morning to alert the community of the locations and number of implosions that could be expected that day.

In spite of such efforts, in well-populated areas, local fire and police departments and the 911 emergency system received an average of 30 to 60 calls from residents each day; on Saturdays, that number was closer to 200. The 911 operators who were briefed before work started responded with a high-level explanation of the work. If the caller asked for more detailed information about the project, the 911 operator referred the caller to NU's public liaison's office phone for follow-through.

NU's Liaison

A NU representative coordinated work with the civil engineering contractor who cleared rights-of-way and readied the work areas ahead of Quanta's crews. He also worked with local conservation commissions, land owners and local officials to make sure the rights-of-way were returned to their original condition. In many cases, the crew built temporary bridges and used matting for swamp and creek crossings. Workers also performed silt fencing and reseeding in affected areas when necessary.

In a few cases where the splice was over water, the existing transmission line had to be de-energized, pulled out, re-spliced on the ground and restrung over the river or waterway. The design of the mouth of the implosive sleeve allowed the conductor to move freely through stringing blocks, without risking damage to the new splices, the conductors or the stringing blocks.

A Success Story

NU's critical implosive splice connector project was a success on many levels. Crews completed the project about 30 months sooner with imploding splice technology than they would have with conventional connector technology. In addition to completing the job under budget, not a single safety issue was reported during the seven-month course of this high-risk project.

Of the 970 connectors replaced using the implosive method, NU experienced only a single faulty splice, which was easily replaced. Since the project's completion in 2007, there have been no reports of a new splice or connector failure.

One of the benefits of implosive splicing is the ability to know immediately if a splice is improperly installed. If the conductors are not fully inserted into the connector sleeve at each end, an hour-glass shape can be seen in the sleeve, revealing a void on the otherwise smooth, straight tube.

The result of this groundbreaking work is electrically efficient and mechanically stronger connections than would have been possible using conventional methods, while effectively solving a major problem on the Northeast transmission grid.

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Carl Tyburski is supervisor of Transmission Lines & Field Contract Services for Western Massachusetts Electric Co. (WMECO), a wholly owned subsidiary of Northeast Utilities, where he has worked for 23 years. Based in Hadley, Massachusetts, Tyburski is responsible for line construction and maintenance in both Connecticut and Massachusetts.
tyburcj@nu.com

Lucas M. Moore is a technical advisor for Quanta Energized Services (Houston, Texas), the parent company of PAR Electrical Contractors Inc. (Kansas City, Missouri). Moore has been a journeyman lineman for seven years and received his barehand certification in 2005.
LMMoore@QuantaServices.com