Unions representing 400,000 of 500,000 railroad workers have now ratified contracts calling for a wage increase of more than 10 percent next year, government officials said yesterday.

Although the increase extends the administration's voluntary wage and benefit guidelines of 7 percent for next year, an exemption was written specifically to protect industries like the railroads where unions are negotiation based on a pattern set before the guidelines were announced Oct. 24.

The settlement, negotiated last summer, calls for a wage increase of up to 35 percent, depending on inflation rates, over the next 39 months. It also provides for some benefit increases, but the cost of these improvements has not been made available.

Only two of the 13 rail unions have yet to ratify the contract, the small train dispatcherss' union and the 100-000-member Brotherhood of Railway and Airline Clerks (BRAC), which is seeking a larger wage increase and other changes in the contract.

BRAC, which shut down most of the nation's rail service for four days last September as the result fo a dispute with the Norfolk and Western Railway, is suing the government for autrict Court here, but BRAC is also scheduled to resume negotiations with the industry under the auspices of the National Mediation Board next Tuesday.

The strick over the Norfolk and Western dispute was halted by a court order that remains in effect until Jan. 14, eliminating the risk of a strike resumption the risk of a strike resumption over the Christmas holidays. Meanwhile, a presidential fact-finding panel is due to make a report on the dispute next week.

The new signatories to the national rail contract are four shop craft unions, which signed yesterday, and the International Association of Machinists and the Sheet Metal Workers Union, which ratified the pact Monday after rejecting it in earlier votes.

The shop craft unions cover about 80,000 workers, the fourth largest grouping of railworkers involved in the negotiations. They include the electrical workers, carmen, blacksmiths, boilermakers, firemen and oilers unions.

The Council on Wage and Price Stability said yesterday it would have to examine the contracts before it could say whether they are exmpt. However, Labor Secretary Ray Marshall said when the guidelines were announced that the exemption for so called "tandem," or pattern, bargaining was written specifically with the rail unions in mind.