The men were using a penetrometer to test soil density in Great King St, in front of the Willowbank Quarter, when it struck a 6600-volt cable buried about 60cm below ground at 10.12am.
The pair were working for Wellington geotechnical drilling company Griffiths Drilling.
Delta's general manager of asset management, Adam Fletcher, said the sharp point of the penetrometer pierced the high-voltage cable, causing an earthing of the cable and an electric arc flash.
Another man who was working in the area at the time said he and his colleagues went outside after they heard a "heck of a bang" to find "quite a bit" of smoke in the area.
He said one man had burns on his legs and up his front and his hair was singed.
A St John spokeswoman said the more seriously injured of the men received burns to about 10% of his body, mainly on his arms and legs.
The second man received moderate burns to his arms and legs.
They were taken to Dunedin Hospital for treatment.
Thirty-nine Delta customers were without power for 32 minutes while the company took the damaged cable out of service and arranged alternative supplies.
Griffiths Drilling managing director Mel Griffiths did not return calls yesterday.
Mr Fletcher said Delta's advice to anyone planning to dig or probe into the ground was to obtain cable-location plans before they started.
"They are available free of charge. A full onsite cable location service is also available. Please call 0800 4DELTA before digging."
There were live-wire warning signs in the area.
A Department of Labour spokeswoman said it had started making inquiries about the incident.
