In 2012 one of the 150kg drones crashed into a control vehicle while it was being tested by the military in South Korea, killing one of the engineers flying it.
The company says it was due to operator error and new measures had been put in place to prevent a similar crash.
Transpower says if it did commit to the camcopters - valued at more than $1 million each - it would only use them in rural areas.
They would be fitted with high-powered surveillance cameras with thermal imaging capability to locate problems in Transpower's 12,000km of high voltage lines which run the length of the country.
The machines have a top speed of around 200kph and have a range of up to 200km from the container-size operating base.
The grid operator says the aircraft are smaller and quieter than manned helicopters and not having patrols eliminates the need to enter properties. It is also trialling robots which attach to lines to test the condition and a miniature 4x4 vehicle for remote inspection of switchgear, plant and equipment, and therefore faster restoration times.
Chief executive Patrick Strange said the high-tech push was not aimed at having fewer lines staff but to make the job safer and make them more effective.
Schiebel chairman Hans Georg Schiebel said the UAVs were for surveillance use only and were not powerful enough to carry weapons.
"Over the last years we have a large number of customers in the military but the technology [now] primarily goes into civilian markets which is growing for unmanned robots in an incredible way," he said.
They were suited to any job that was "dangerous and dirty".
