Twelve schools stayed closed and several tram lines remained out of action in the southeast of the German capital.
Police had said Tuesday they "do not rule out a political motive" after an unnamed anarchist group had posted a claim of responsibility online for setting the blaze.
Initially some 50,000 customers were left without electricity, and the Stromnetz Berlin grid operator has been working to reconnect them ever since.
Customers who have power were asked to use electricity "as sparingly as possible" until the whole network is up and running again, Stromnetz Berlin spokesman Henrik Beuster told AFP.
The operator said it hoped to have all those affected reconnected by Thursday evening.
The Berlin fire service warned that the 112 emergency number might not be accessible in parts of the affected area, and that several temporary emergency service centres had been set up.
READ ALSO: Police say political arson may be behind Berlin blackout
Police were also performing extra patrols through the district.
Four other centres where residents can access wireless internet and charge appliances will stay open for now, the district council told AFP.
Germany has been on high alert for sabotage activities directed at its infrastructure from militants and also foreign actors such as Russia.
Last month three fires hit parts of the German rail network, with a far-left group calling itself the "Angry Birds Kommando" saying it was behind at least one of them.
Also on Wednesday the German government agreed a draft law aimed at better protection of critical infrastructure against sabotage, militant attacks and natural disasters.
The law identifies enterprises deemed critical for the population and the economy, in sectors ranging from energy to water and food, transport and healthcare, and obliges them to draw up emergency response plans.
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