ALTHOUGH LARGER PLACES like Toronto and Orangeville took the lead, the idea of joining in this year's global Earth Hour initiative Saturday evening is clearly gaining momentum, raising some interesting questions as to its potential impact.

For example, in a press release Wednesday, Shelburne Mayor Ed Crewson asked residents to turn off "all discretionary power usage" at 8 p.m.

"Street lights, water production, sewage processing, police and fire services which are essential to our citizens will continue, along with snow removal if necessary but the powering of all other services will be switched off for this one hour," the mayor explained, while urging residents to turn off the television, and the lights and enjoy a cozy hour at home, in the dark, with loved ones.

Well, if that is indeed how it plays out, and the most significant observance in Dufferin is merely a candlelight gathering at Orangeville's Alexandra Park, Terry Young's prediction as spokesman for Ontario's Independent Electrical Supply Organization - that the impact on Ontario's electricity grid will be merely 800 megawatts - may well be bang-on.

But while determining what constitutes a nonessential use of electricity may be easy for a municipality and even easier for a homeowner, that's hardly the case when it comes to commercial operations.

Take, for example, a modern movie house, which clearly relies heavily on electricity for a lot more than projecting images on screens. Anyone familiar with Orangeville's Galaxy Cinema knows full well that a lot more power is used in the confection areas and for general lighting than is needed to show the films.

Then again, although it might be relatively easy to change the movie schedules Saturday so no film was in progress between 8 and 9 p.m., some electricity is needed these days to operate even the ticketing machines.

As we see it, province-wide observance of Earth Hour by the commercial and industrial sectors could well have an enormous impact on the power grid, whereas non-observance by those sectors and by most of the population would have virtually none.

Whatever the case, the initiative ought to be welcomed, even if all it accomplishes is to make a lot of us think twice about how much electricity we are consuming, and to see how easily we can get along without some of it.

Then again, a lot of us have increasingly been given first-hand knowledge, in the form of unpredictable blackouts that often last far longer than one hour.