Vermont transmission line vandalism

Vermont's electric transmission authority has reported vandalism to a section of high-voltage line connecting Hydro-Quebec's grid to southern New England markets.  According to the Caledonian Record, 167 insulating discs were shot out from a transmission line in the town of Concord, Vermont.

Vermont Electric Power Company (VELCO) manages Vermont's electric transmission system, which includes, 738 miles of transmission lines, 13,000 acres of rights-of-way, 55 substations, switching stations and terminal facilities, interconnection facilities with Hydro-Quebec, as well as fiber optic communication networks that both control the electric system and provide the backbone for high-speed data internet access. VELCO was formed by the state's utilities in 1956 as the nation's first statewide, "transmission only" public utility.

Vandals reportedly used a shotgun to shoot the glass insulating discs which are spaced along the transmission lines and are designed to keep the lines safe from shorting out.  In all, 167 out of over 400 insulating discs were destroyed.  As a result, VELCO depowered the line until the discs could be replaced, which took from last Friday until last Sunday.  The repair itself cost about $250,000, but the biggest cost arose when regional grid operator ISO New England was forced to turn to the spot market to replace the electricity normally imported over the line from Quebec while the line was down.  The cost of that replacement power was reportedly over $1 million per day.

The incident is now the subject of a federal investigation.  Laws enacted after the widespread eastern blackout in 2003 and the September 11 terrorist attacks have increased the penalties for disrupting electric transmission and other infrastructure.  The insulating disc shooting may be treated as a "terrorist act" under federal law.

Transmission lines provide value to society, but are typically expensive and are often located in remote areas.  Hunting often occurs along or near transmission lines; just this year, VELCO won the National Wild Turkey Federation's Energy for Wildlife award for the company’s ongoing commitment to develop and improve wildlife habitat along its rights-of-way.  The extent of the damage to the insulating discs makes the shooting appear to be intentional, and thus more than a "hunting accident".  How will the incident affect transmission line owners' policies about public access to areas near lines?  How can transmission lines be better protected against vandalism?