ASHLAND, Ky. (AP) _ A federal court jury that said outdated aluminum wiring in a wall outlet was a factor in a 1977 supper club fire that killed 165 people will now decide if General Electric Co. should be held liable for the disaster.

The jury's ruling Monday reversed the finding of an earlier trial of the case involving the Beverly Hills Supper Club fire. The panel will hear arguments Thursday on whether GE, the last defendant in the case, should be held liable in the nightclub disaster.

After the jury's verdict, Stanley Chesley, the plaintiffs' attorney, grinned and rested his head on his folded arms.

''This is the last time that 165 victims of death and 81 of injury can come before their peers and plead their case,'' he had told the jury.

Chesley said later he was ''pleased as punch, proud as can be,'' but wouldn't comment further because the trial is not over.

Of the 14 initial defendants, makers of the pre-1973 ''old-technology'' aluminum wiring or such devices as switches and outlets, 13 negotiated out-of- court settlements since the retrial began April 30. The amounts of the settlements were not reported.

GE did not make the wiring but produced devices used with it. Trial testimony didn't address whether a particular company's products were used in the club.

For GE to be found liable, the jury would have to uphold the plaintiffs' claim that no matter whose products were used, the companies shared liability because they allegedly ''acted in concert'' to keep the products on the market despite reported hazards.

If GE is found liable, the question of damages would be addressed in another phase of the trial. The class-action filed by the families of those killed and by 81 of those injured did not specify an amount.

The jury deliberated 85 minutes before ruling that an aluminum-wired outlet ''was a substantial factor causing the fire'' that destroyed the club at Southgate in northern Kentucky, across the Ohio River from Cincinnati, on the night of May 28, 1977.

Attorneys William McCracken and Charles Brown of Columbus, representing GE, showed no reaction to the verdict and declined comment.

Defense attorneys had reviewed evidence for their theory that the fire started with a short circuit in the copper-wire cord of the pump in a decorative fountain, or a copper-wired outlet it was connected to. Chesley argued, ''Clearly, there is no evidence'' for the pump-cord theory.

In closing arguments, attorneys thanked the jurors for their patience in the 10-week-old trial. U.S. District Judge Henry R. Wilhoit Jr. also noted the duration of the proceedings, saying, ''I know it's been a long trial because I've had three haircuts.''

Wilhoit referred to the out-of-court settlements, admonishing the jury, ''This case has been terminated as to all defendants except the General Electric Company, and you should not concern yourself with the disposition as to them.''

He had rejected a defense motion to dismiss the suit because of publicity on the settlements and questions about how the jury would interpret the diminishing number of defense attorneys.

A 1980 jury that deliberated two hours found aluminum wiring blameless in the fire. The 6th U.S. Circuit Court of Appeals ordered the retrial, saying the verdict could have been affected when a juror checked aluminum wiring in his home, decided it was safe and told the other jurors.