OTTAWA - A raft of measures implemented after the massive August 2003 blackout has dimmed the prospect of another widespread power shortage today, says the organization that oversees North America's interconnected energy grid.

The North American Electric Reliability Corp. (NERC) says beefed-up reliability standards have been the most significant development to come out of the blackout, which plunged more than 50 million people in Ontario and parts of the northeastern United States into darkness for days.

"The single most important thing is modified, mandatory and enforceable reliability standards in the United States, and we are working towards that in all of the provinces of Canada," said NERC's president and chief executive officer, Rick Sergel.

Before the blackout, NERC couldn't back up its orders with the force of law. Now, it can fine U.S. companies up to US$1 million every day for each reliability standard it has failed to meet. NERC can also fine a handful of provincial utilities that fall under its purview.

Most provinces, including Ontario, already have some form of mandatory reliability standards and the power to enforce them.

Reliability standards are the minimum requirements that are needed to ensure the safe and stable operation of the power grid. That could be something as simple as specifying how much distance needs to be between treetops and power lines.

The 2003 blackout began with a sagging transmission line brushing against some trees in northern Ohio.

Seven minutes later, North America's power grid had fallen as one circuit breaker after another tripped off like a row of dominoes.

The power outage hit Ohio, Michigan, Pennsylvania, New York, Vermont, Massachusetts, Connecticut, New Jersey and Ontario, affecting a total area of 24,086 square kilometres.

It took four days before power was restored in the U.S., while brownouts and rolling blackouts persisted for more than a week in parts of Ontario.

The economies of both countries lost billions of dollars and Canada's gross domestic product fell 0.7 per cent that month.

In its 2004 report, a binational panel that included Canada's natural resources minister and the U.S. energy secretary deemed the power outage "preventable."

The 238-page report recommended forcing companies to comply with reliability standards, with stiff fines for those failing to do so.

The report found Ontario -- which instituted mandatory reliability standards more than a year before the 2003 blackout -- to be a model for system operators.

NERC recently audited Ontario's Independent Electricity System Operator (IESO), which is responsible for the day-to-day operation of the province's electrical system, and found it fully compliant with all standards, says the IESO's Kim Warren.

"In Ontario, there's very little that has changed (since the blackout) because, frankly, we were already there," he said.

That's not to say improvements aren't needed.

The Ontario Power Authority plans to overhaul the provincial electricity system. The plan, which is in the approvals process, has allotted $4 billion to update transmission and distribution lines. The work is expected to be finished sometime in 2012 or early 2013.

Cherise Burda, director of the Pembina Institute's Ontario program, says the province should diversify its power supply to include more renewable and green energy.

"If we continue with our current centralized energy system, we're vulnerable to power mishaps," she said.

"We're also vulnerable to being left behind in the energy economy."