Council workers were evacuated due to a power cut in the civic centre.
Northern Powergrid said 210 properties were affected in the SR1 and SR2 postcode areas this afternoon.
The electricity supply went off at around 1.35pm, but engineers had it restored by 2.01pm.
A spokeman for the company, said all the power should now be back online.
However, if anyone is still without power, or are experiencing problems, they should try resetting their trip switches.