American Security Bank announced plans yesterday to begin installing the largest automatic self-service teller system in the area and may eventually include teller units in supermarkets and drug stores.

The $2.5 million network of 100 automatic tellers will be installed in 20 bank lobbies and two each will be located in the enclosed entrance of each of the 33 branches.

Within the next two years, when the system is expected to be installed completely, seven new branches will be added to the bank system, which will also have two terminals each, Victor Feigelman, vice president of data processing systems at the bank, said yesterday.

The installation of units outside branches is not within the bank's immediate plans, but is being investigated, Feigelman said.

"We're talking to people in the grocery and drug industry about installing automatic teller units there," Feigelman said. "I think that's the kind of thing you can expect from American Security in the future."

By next October the bank plans to have some of the systems operating with 12 working in six banks by the end of the year.

Eighty terminals will be placed in branch vestibules, the enclosed space just before reaching the bank lobby. Customers can gain entry by inserting a card in the front door but they will not be admitted to the bank itself. That same card and an individual number allows a bank customer to make withdrawals, deposits, pay certain bills, report account balances, transfer funds and eventually grant loand, Feigelman said.

Although the system is expected to relieve the workload of some tellers and bank employes, no cutback in staff will result from the addition of automation, Feigelman said.

"With these new automatic teller terminals, customers will be able to take care of most of their money management requirements quickly and safely," said bank President W. Jarvis Moody. "We already have the largest branch operation in the city and these new terminals will further enhanced our ability to serve Washington consumers."

Many banks in Washington already have automatic teller units. Feigelman said American Security waited until now to install its new machines to get the latest in electronic equipment.