The cost of Virginia Electric and Power Co.'s projected 10-year construction program could force the utility's 1.1 million customers to pay an extra $50 million in annual rate increases, with rising fuel costs adding another $60 million, the State Corporation Commission said yesterday.

SCC spokesman John Daffron said Vepco and SCC officials will hold a series of meetings next month to determine if all of the projects in Vepco's $6 billion construction program are necessary.

"We're not accusing them (Vepco) of anything." Daffron said. "There are just questions that need answers." He said the SCC last week hired a consulting firm, at a cost of up to $130,000, to thoroughly investigate Vepco's management and construction programs.

A Vepco spokesman said the most recent rate increase granted by the SCC to Vepco was last December, when the company was allowed an 8.5 per cent, or $66.3 million, boost in rates. That increase meant the owner of a typical all-electric home paid about $8.88 more a month in the summer for 2.500 kilowatt hours of electricity and $10.79 in the winter.

Daffron said it is impossible at this point to predict how much the average customer's bill would go up if Vepco planned construction projects are built, because it would depend on how the rate increases are apportioned among residential, industrial and commercial users.

Vepco and SCC officials have exchanged letters this month concerning Vepco's future construction plans, but the utility and the regulatory agency disagree on many points.

In a statement yesterday, Vepco's board of directors said it has sent a letter to the SCC in support of the management of its company.

Vepco's directors expressed concern that the SCC "does not seem to realize just what is necessary to assure electric energy to the people of Virginia."

Vepco's directors expressed concern adequate earnings to attract money to pay for construction and claimed that "the commission has not permitted the company to charge rates that would yield adequate earnings. If that continues, construction must stop, and an era of brownouts, blackouts and limitations on new connections will have begun."

The increased annual cost to Vepco customers in Virginia will come from the interest charges on the borrowed money for the construction, Daffron said.

"We're concerned at what point electricity will start advancing faster than the cost-of-living index," Daffron explained." . . . We want to put a crimp on this increase if at all possible, but we don't want to crimp them so much that when you push a button (to turn on electricity), nothing happens. Worse than expensive electricity is none at all."

He said the SCC will examine such things as construction schedules and their impact on customers, whether Vepco can meet future demand for electricity, and possible waste and mismanagement by the utility.

In response, Vepco officials countered that the alternative to not building the new facilities is "far worse than periodic rate increases. It would bring Virginia" economic growth to an absolute halt.

"Power would have to be rationed and curtallment plans drawn up by the commission. New industry would go elsewhere and [WORLD ILLEGIBLE] would rise. This should be an unacceptable alternative to the commission," Vepco said.

Vepco officials also noted that many of the factors which cause rate increases are national in scope "and beyond Vepco's control." The utility listed strip mining legislation, rising fuel costs, proposed changes in the unclear industry, and the Carter administration's policy not allowing the reprocessing of spent uranium fuel.

Vepco currently has under construction four large nuclear units and six hydroelectric units. The completion of these facilities are included in the 10-year plan.