In the waning weeks of 1976, with the cost and consumption of electricity in Metropolitan Washington already at an all-time high, the three electric utility companies serving the area received rate increases totaling $120.69 million.

This means consumers in the District, Maryland and Virginia are paying from 7 to 8.5 per cent more a month for electricity as the cost of fuel to run generators rises, as inflation in other costs also takes its cut and as utilities strive to pay higher dividends to investors to attract the private investment capital they say they need to build new plants.

At the heart of the electricity rate spiral are consumers themselves who have been on an energy binge since World War II, consuming increasing qauntities each year with only a momentary pause in 1974 to absorb - and then forget - the "news" that an energy crisis was building.

Government and industry conservation programs - which came along on a better-late-than-never basis - have had an imperceptible effect on slowing the increase in energy consumption, particularly of electricity.

Edison Electric Institute spokesmen say that, historically, Americans have increased electric consumption by about 6 or 7 per cent each year. As we moved into the 1970s, utility economists projected a sharp rise in that growth rate to 10 or 11 per cent. But the Arab oil embargo made the projection valueless. Growth sunk back to its normal, steady climb.

Some utilities, however, were caught with commitments for facilities to increase generating capacity. They continued to seek rate increases to help pay for new plants they did not need.

Locally, the Potomac Electric Power Co. in particular was surprised by below-projection electricity consumption. At the end of 1976, as it did the year before, pepco announced a slowdown in expansion of its generating capacity.

Even so, calculations show that the three local companies - Pepco, the Baltimore Gas and Electric Co. and Virginia Electric and Power Co. - plan to spend $12 billion or more in the next dozen years to build new generating capacity. This includes at least seven nuclear power plant reactor units - one of which would be a new plant.

The new nuclear plant, Perryman, is planned by BG&E for construction by 1986 on Bush River, a tributary of the Chesapeake Bay West of Aberdeen Proving Ground.

Increased power consumption - with no sign of a slowdown in the projected 6 per cent annual increase - is occurring despite warnings by experts that the nation faces a real energy crisis in the early 1980s.

The Edison Electric Institute a national association of utility companies, issued at least two formal warnings in the last quarter of 1976 that energy proglems will catch up with us unless more coal and nuclear energy, rather than oil and gas, are used to generate electricity.

Federal government policy calls for increased conservation plus heavier reliance on coal and nuclear energy, but the potential crisis still looms, experts maintain.

Consumer groups (local and national), several state legislatures and Congress have proposed or are considering innovations in rate-setting procedures in an effort to ease the financial burden on consumers and to save energy.

Locally, versions of two proposals by consumer groups and one by utilities have been considered by the regulatory agencies - the public service commissions in the District and Maryland and the State Corporation Commission in Virginia.

The Proposals:

That regulatory agencies calculate new rate bases on a "projected" period of time rather than on the "historical" time periods now used. Utilities maintain tht by the time the regulatory process is completed - including public hearings - increases they receive based on actual costs the previous year already are eaten up by inflation and they must file again immediately for another increase.

That "time-fo-usage" meters be used to pinpoint what time of day a customer uses the most electricity and that rates be structured to encourage larger usage in off-peak hours. Those who managed to use power late at night rather than during daytime hours, when commercial and industrial use is heavy, would receive a lower rate.

That "lifeline" rates be established to guarantee at least a subsistence amount of electricity to low-income customers whether they can pay for it or not.

At the heart of the utility company problem is the necesity to project customer demand. Over the past decade, average customer consumption has about doubled, according to the statistics of all three local companies.

Consumer groups blame the companies for failing to foresee the smaller increase in demand, which resulted in a surplus of generating capacity. Those groups also hold the companies at least partially responsible for the steady increase in consumption of electricity because of the intensive advertising campaigns through the 1960s conducted for all-electric homes.

But even though the growth in demand has slowed, and even though most utility companies - particularly the local ones - have replaced calls for "all-electric homes" with conservation messages in their advertising, the companies maintain they must build more power plants to meet the next decade's demands.

The companies say they are in a financial bind caused by the need to build, by the inflation of construction costs, by spectacular increases in coal and oil costs, and by the fact that most utility stock is sluggish and priced below book value.

Their salvation, and their continued ability to meet consumer demand, lies in increased rates, they say.