Firefighters were called after an explosion at the Rolls Royce site in Hucknall.
Fire crews from Hucknall and Stockhill were called after a “small explosion” was reported in an electricity substation.
Staff were evacuated from the Watnall Road site shortly after 6.10am on Wednesday and a cordon was put in place by the fire services.
A Rolls Royce spokesman said:
“Following a power cut in the Hucknall area, we can confirm that there was a small incident at the electrical substation on our Hucknall site yesterday morning. This problem led to a loss of power at our Rolls-Royce facility. There were no dangers to personnel, but due to this power failure, we made the decision to send a number of employees home. Western Power Distribution Engineers were on site and fixed the problem allowing the afternoon shift to take place as normal.”