THE WEDNESDAY-night blackout and it aftermath stripped away more than one facade. It revealed the awesome dependence of major cities on electricity and, therefore, on the energy that is needed to provide it. It demonstrated that back-up systems, protective devices and reliability studies are relative things. And it laid bare the real heart of New York City, uncovering the bad and the good that lie behind its once-slick but now-tarnished image.

There will be, no doubt, a great hunt for the villian other than those bolts of lightning. Maybe one will be found - in inadequate planning, insufficient installation of equipment, human error or a combination of these - at the power company, which is where New Yorkers, not wholly without reason, traditionally look first.Whatever the investigating teams conclude, nothing will alter the love-hate relationship that has long existed between Consolidated Edison and the citizens of New York. The city can't live without it and, if you listen to its residents, hates to live with it. Mayor Beame's immediate leap to the conclusion that Con Edison had been grossly negligent reflects that view, even though his comments ought to be taken in the context of the political campaign in which he is engaged.

There is some evidence, of course, that Con Ed is not one of the better power companies in the nation. And there may be more evidence once the investigations are concluded. But there is also some evidence that New York City is not one of the better places in which to attempt to deliver electricity. An unusually high percentage of the city's power has to be bought from other companies and transported substantial distances because environmental objections have made it impossible for Con Edison to build more generators close to its customers. That trade-off - long range transmission of electricity with the increased potential of blackouts, in exchange for less close-in pollution - is among the issues that need to be reexamined.

We suspect that every other major city in the country - and the minor ones, for that matter - are vulnerable to similar blackouts, given the right combination of events. We wouldn't encourage anybody to place too much faith in assurances of the "it-can't-happen-here" type. Too many examples in which blackouts occurred or almost occurred earlier this year have already been documented. So we look forward to the reports of the investigating bodies for proposals not only how to avoid future blackouts in New York but for information on what preventive measures might be advisable for other parts of the country.

If we were in New York right now, however, we would be concerned as much with what happened after the blackout began as with what happened to bring it about. Those who live in affluent sections of the city took the darkness in stride, alternating between denouncing the power company and doing things to help themselves and others cope with adversity. But the looting and burning in the poorer sections of Harlem, the Bronx, Queens and Brooklyn are terrible indictments of the state of the city, its government and its people. There will be much analysis in the next few weeks about why that happened - the weather, unemployment, anger, frustration, just plain meanness - and we are not about to speculate. Suffice it to say now that, in a variety of important respects, the New York that New York revealed to the world Wednesday night is something less than a wonderful town.