Families in Darwin House and Perth House, in Australia Close, Landport, have no power.
Councillor Gerald Vernon-Jackson was told by residents they had no power while he was out door-knocking for the election.
He said: ‘It’s right in the middle of town, somebody has dug through the main power cable. None of the security doors work, no lights work.’
Roadworks are being carried out in Arundel Street.
An SSE spokesman said 48 homes had been hit by the power cut.
He said: ‘The power went off in Australia Close in Perth House at 3.12pm.
‘We expect it to be back on by 11pm.
‘We’ve got engineers on site to repair damage to an underground cable.
‘We’d like to apologise to customers affected by this.’
He added homes near Perth House may be affected too.