A drunken security guard was blamed yesterday for shutting down a huge utility substation and causing a total blackout of Memphis as the city entered the sixth day of a tense firemen's and policemen's strike.

Richard David Hyder, 29, a private security guard hired to protect the substation, admitted throwing a bank of switches. Hyder admitted responsibility during a court hearing yeaterday and was being held under a $10,000 bond at a Memphis jail last night.

Authorities said there was no apparent connection between the blackout and the strike.

Meanwhile, attorneys for striking firemen and policemen huddled for almost three hours with Mayor Wyeth Chandler to discuss a union proposal to end the strike. After the meeting, fire union attorney Allen Blair refused comment on any movement in the negotiations but he appeard optimistic about the renewed talks.

Union leaders were close-mouthed about details of their offer. However, it was believed the strikers would return to work if Chandler agreed to negotiate one-year contracts, take no reprisals against the strikers and offer a 7 percent wage increase.

When contract talks broke off last weekend, negotiators seemed close to agreement on a wage package. But since then, salary differences have been overshadowed by disputes revolving around the life of the contracts and possible reprisals.

Chandler said the considers those firemen and policemen who have not returned to work to have resigned. And the city personnel office has been busy cashiering those who continue to strike.

The blackout struck the city at 12:33 a.m.. Central time, creating a graveyard-like atmosphere for 700,000 dumb-founded residents. Memphis Light, Gas & Water officials worked frantically to identify the source of the blackout as callers jammed the switchboards.

Scattered incidents of looting blared across police radios, but officials said no deaths or violent incidents resulted form the blackout.

At 3 a.m. power was restored to the city and, at the substation, Hyder was taken in custody. He was later charged with interfering with power lines, a feiony offence punishable by a one-to-ten-year jail sentence.

Inspector William Maley of the Shelby County sheriff's department said Hyder registered a high level of intoxication almost six hours after the switches were thrown. Maley said Hyder apparently showed up for work before midnight highly intoxicated.

"He said he didn't know why he did it, that he was just drunk," Maley said. The inspector added that no special knowledge of electronics was necessary to shut off the switches. Nonetheless, peculiar circumstances surrounding the blackout remained under investigating. Hyder, who lives in Nashville, was brought to Memphis by Murray Guard Service on Monday to help secure the substation. On that same day the Tennessee National Guard removed a patrol from the station to beef up security at Memphis firehouses as firemen joined the police strike. Hyder's partner on the security detail was making a perimeter check when the city blacked out.

Bob Brown, Hyder's supervisor, said the security firm has been under contract with the utility company to guard key equipment for almost three years. He said that without prejudging the charges, Hyder would be fired for being drunk on the job.

Elsewhere in the city yesterday:

More than 10,000 Elvis Presley fans trooped through Graceland mansion to view the singer's grave in observance of the first anniversary of his death. But a memorial concert to raise funds for a Presley museum in the city was called off because of the strike. A full complement of 248 sanitation trucks was in service, compared to only six Tuesday. The fire department continued to operate with about 50 percent manpower but reported fewer than normal fire calls.

County deputies remained on duty in the city while 1,200 National Guardsmen secured fire stations and police precincts.

The city curfew was rolled back by two hours, making it from 10 p.m. to dawn, as a sign that tensions were easing.

Chandler remained under political pressure yesterday, however. Tennessee Gov. Ray Blanton issued a harsh statement calling for the mayor to agree to binding arbitration in the dispute. Blanton said Memphis would be billed about $1 million for use of the National Guard during the 1968 garbage strike, the firemen's strike of six weeks ago and the current civil emergency. The governor said a day's use of the guard costs $65,000.

City Councilman John Ford. a frequent critic of the mayor, yesterday urged Chandler to end the strike with a 7 percent wage increase, a one-year contract and no reprisals. Ford said the city could afford the pay rises but not the cost of the strike.