The AT&T Inc. [1] (NYSE: T [1] - message board [1]) investigation into an exploding VRAD cabinet may be over, but (sadly for my editors) the story lives on. (See AT&T: Defect Caused VRAD Explosion [2].)

The carrier this morning has provided details of a second incident involving Avestor's batteries, the ones that were said to be the cause of an October 2006 broadband equipment cabinet explosion in suburban Houston. (See AT&T Investigates DSLAM Explosion [3], AT&T Still Digging on DBLAM! [4], AT&T Eyes Batteries in Explosion Probe [5], and Exclusive Photos: Fire to the Node [6].)

The initial VRAD (video-ready access device) explosion occurred in the 8200 block of Clover Gardens Drive. This second incident, a VRAD that caught fire but didn't explode, happened in January 2007 -- "20 miles away" from the first mishap, according to AT&T. Light Reading hasn't been able to determine the exact address. Yet.

"A similar battery produced a small fire in another cabinet, but it was nowhere near the magnitude of the first incident. Both cases were studied in the investigation," writes an AT&T spokesman in an email to Light Reading this morning.

Our query on this new incident was sparked by AT&T's statement yesterday concerning the conclusion of its investigation into the safety of the Avestor batteries in its network.

Given that AT&T has 17,000 Avestor batteries in its network, and this latest admission of a "small fire" involved hazardous materials, some say the investigation, though closed, has suddenly become more alarming. "There's no such thing as a small fire in a residential neighborhood, especially when the fuel is a lithium metal polymer battery," says an industry analyst who asked not to be named [7].

AT&T says its investigation, conducted by Exponent Inc. [8], found that "the incidents in Houston were most likely caused by a manufacturing defect in those two batteries."

The two batteries referred to were housed in two different VRAD cabinets, 20 miles apart, in the same city within a few months of each other. But, the carrier says, apart from those two batteries, all else is well. In its statement, published earlier today, AT&T said "the battery design was sound, as were the safety features," and concluded that "the risk of hazardous failures with this battery is as low, if not lower, than the risk with alternative batteries, which are used by other telecommunications and cable companies in similar applications."

"Outside of these two incidents, there have been no similar incidents involving these batteries," AT&T's spokesman writes via email.

— Phil Harvey, Fire Marshal, Light Reading [9]