Like most cities, the power grid is underground—a vast subterranean network of vaults and conduit paths that house the electric facilities.

“Nobody has any idea where the power comes from for downtown Boise,” said Rod Thompson, superintendent for Track Utilities.  “They don’t understand there’s a whole system underground with vaults and switches.”

Idaho Power has nearly 50 vaults downtown­—large rooms full of old transformers the size of small cars.  The only obvious evidence of vaults are the manhole covers.

A maze of conduit connects the vaults, and inside the conduit are the heavy, insulated wire cables that transmit the electricity.

“It’s necessary to replace the switches and the cable together,” said Project Manager Tom Barber.  “The new cable’s not compatible with the old switches and vice versa, so we have to change out everything.”

Some underground equipment dates back as far as 1916, but the majority is 1940’s-era.  Parts are no longer available when repairs are necessary.

As electric demand continues to increase downtown, more capacity and switching capabilities are needed.

“The equipment has a given life and it’s been 60 or 70 years. That’s more than you can ask of that old equipment, so it’s time to replace it,” Barber said.

The upgrade to Boise’s downtown underground system is expected to be complete in 2012.