The blaze caused an overnight power cut for about 2,500 customers.
Firefighters were called to Lyndhurst Meadows shortly before midnight, after bins were placed close to the sub-station and set alight.
Station commander Michael Roberts said the sub-station was “wiped out”.
The power cut affected homes and businesses in the Springfield Road area but all were reconnected by 6 am this morning.
Ten firefighters were involved in the operation.
But fire chiefs say because of the dangers posed by the very high voltage, their commander said the only action they could take was to keep nearby properties safe and advise residents to stay indoors.
The roof and gable of one property had to be hosed down to prevent it from catching fire.
Local resident and former DUP councillor Nicola Verner described the arson attack as “reckless vandalism”.
Ms Verner said those responsible had put people at risk, including her elderly neighbour who lives nearest the sub-station.
She said the man is in ill health and has mobility problems and the arson attack had left him in “a very vulnerable position”.