Voters in northern Fairfax County, Fairfax City, and Falls Church went to the polls yesterday to select five Republican and five Democratic candidates for the Nov. 8 House of Delegates race from a total field of 17. Early returns were incomplete.

Voter turnout was considered light as the candidates, including three incumbents, conducted what was generally acknowledged to be a lackluster and largely issueless campaign.

While the incumbents touted their experience, the challengers argued that government needed new men and woemen to provide new approaches to problem solving.

There are 141,436 registered voters in the 18th District which covers 200 square miles and includes such jursidictions as Herndon; Vienna, and the new community of Reston as well as Fairfax City and Falls Church.

The incumbents in the race were Del. Dorothy S. McDiarmid, seven terms, and Del. Raymond E. Vickery Jr., two terms, Democrats; and republican Del. Vincent F. Callahan Jr., five terms.

In Republican race, early returns showed, Callahan comfortably ahead in the seven-way race for five seats. The contests for the other four places on the Republican ticket this fall were too close to call.

McDiarmid, who lives in Vienna, has been considered a tireless advocate of the ratification of the equal rights amendment and improved quality in education.

Vickery, a 35-year-old attorney who lives in Vienna, has been outspoken on taxes and utility rates as well as education and the state criminal justice system.

Callahan ran unsuccessfully for Virginia's 10th Congressional District seat last November. A partner in Callahan Publications, a newsletter service started by his father in 1944, Callahan is an influential member of the House appropriations committee. He lives in McLean.

There were eight other Democratic candidates and six other Republicans.

Lauretta B. Newport, the 38-year-old former president ofthe Fairfax County YWCA and a Democrat, is the only black in the race.

Democrat Kenneth R. Plum, 35, a Fairfax County school teacher, ran unsuccessfully in the 1976 and 1975 delegates races.

Karetta Browning Hubbard, a 32-year-old Reston Democrat, worked in the Northern Virginia campaign for President Carter.

Barbara W. Weiss, 46, is a Democratic citizen activist who lives in Vienna.

Gary P. Elkund, 31, a Falls Church resident, is the only Democratic candidate from outside Fairfax's Centreville District.

Democrat Richard M. Reimer, 30, is a former president of Reston Commuter Bus Inc.

Embry Cobb Rucker, 62, a Reston resident, is a retired Episcopal priest and also ran as a Democrat. A political newcomer, Rucker's campaign included mostly mail-outs. "I haven't gotten the courage to walk up to strangers to introduce myself yet," he said.

Democratic challenger John D. Scalamonti, 36, a former Catholic priest is currently a training manager with the Gino's fast food chain.

Besides Callahan, the other candidates in the Republican primary are:

Martin H. Perper, who ran last fall as an independent for a seat in the U.S. Senate and lost, is a management consultant, mostly involved in the hotel business.

Peter W. Scott, 43, lost a bid for the Providence District supervisor scat in 1975.

Helga V. Bonney, 34, publishes a monthly cooking newsletter and manages computerized mailing lists for other clients.

Clifford W. Overcash, 49, is the owner of a retail sales uniforms business called Lynford Uniforms Inc. in Fairfax County.

Thomas Rae Cagley, 36, a Falls, Church resident, is an economic research associate.

Michael D. White, 25, is a management consultant who lives in Falls Church.