GM’s recent announcement that its all-electric Chevy Volt will hit the showroom floor by the end of 2010 signaled a major shift in the evolution of plug-in vehicles. With other major manufacturers working on similar initiatives, it looks like electric cars may be hitting the mainstream.

Fully charged, the Volt will run for 40 miles on battery power, which means a typical commuter can travel all week to and from work without using any gas. A gas-powered extended-range mode provides an additional 300 miles. GM places the Volt’s miles per gallon at 230 and estimates it will consume 25 kWh—about $2.75—for every 100 miles.

Ford is not far behind, with plans to have its all-electric Focus available in 2011. Nissan, Toyota, and Honda also have announced upcoming rollouts.

In preparation, builders should be planning ahead to ensure the houses they sell are ready if and when occupants go the plug-in route. “If we’re not ready to get buildings outfitted today, there’s going to be a lot of incurred costs later on,” says Britta Gross, GM’s director of global energy systems and infrastructure commercialization.

Luckily, builders and drivers won’t face unfamiliar technology: The Volt simply plugs into a three-pronged outlet via an extension cord; Gross says the Volt charges in eight hours on a 120-volt/15-amp outlet or in about three hours on a 240-volt/30-amp outlet. Though most detached houses already contain a 120-volt outlet in the garage, forward-thinking builders should consider installing a 240-volt outlet no more than 25 feet from parking spots and providing a dedicated circuit.

Ford also recommends a dedicated 240-volt line to the garage, with 80 to 100 amps to accommodate two cars at 40 amps each. Ford will require a “charge point,” a hard-wired box that contains the cord and ensures it isn’t charged unless it’s plugged into the car.

For multifamily buildings with underground garages, Gross suggests installing a 240-volt outlet at each stall, along with appropriate upgraded transformers, or at least having a percentage of dedicated spaces.

Determining how many parking spaces is still up in the air. In Vancouver, a new building standard will require new multifamily projects to include wiring for vehicle charging in a minimum of 20% of parking stalls. Each building’s electrical capacity must be able to accommodate a load created if each of those stalls were in use simultaneously.

“Consumers … expect a plug for the dryer and stove, and in very short order, they’re going to expect an outlet in their garage,” says John Stonier, spokesperson for the Vancouver Electric Vehicle Association. “It’s not a big stretch to do this, and it doesn’t cost very much.” —Katy Tomasulo