Sorry this is a bit of and old story, but I haven't had much time to post here lately.
After the quake that has happened in Christchurch, there have been some stories of survivors, but one guy could have met a very nasty end indeed:

From Stuff:LINK

Quote
A sub-contractor who came within millimetres of being "vaporised" when he struck a 66,000-volt buried cable says he wanted to "smack" the contractor who told him he was fine to dig there.

Jack Peke, a drainage contractor from Wellington, was breaking concrete under the corner of Ruskin and Antigua streets in Christchurch on Thursday when he noticed what looked to be vegetable oil seeping from a cable he had struck.

He got out of his digger and stuck his finger in the grease, unaware that what he had found was the oil casing of a 66kV cable – the main service line between Addington and a large part of south Christchurch.

If he had contacted the core, it would have created a power spark 20 metres high and an explosion that would have destroyed everything within a 6 metre 18'(T) radius.

Roger Sutton, the chief executive of lines company Orion, said Mr Peke would have been "vaporised" if he had pierced the cable.

Mr Peke said he was the last subcontractor in a chain.

He asked for service plans (maps of underground cables and pipes) but was told he only needed to know about a fibre-optic cable.

Piercing the oil casing dropped the pressure at the sub-station and sounded Orion's alarms. Staff rushed down and found Mr Peke in the hole trying to stop the oil flow.

"We were out of that hole faster than you could say boom."

Mr Peke was shaken when he learned how close he had come to being killed and angry over the bad advice.

"When I found it was a 66kV cable I wanted to smack the contractor out," he said.

He later bought a Lotto ticket, but thinks he has used all his luck.

The cable is being repaired but how long this will take will not be known before Monday.

Mr Sutton said the network was still running but it was fragile because small back-up cables were carrying the load.

One more problem could lead to loss of power for 4000 to 5000 customers.

Service plans had been made available to sub-contractors, but it was "obviously impossible to track everybody", he said.


When it's all said and done though, Mr Peke needs to take a fair share of the blame here.
This and all 66kV circuit cables are covered with bright RED coloured concrete of 200mm thick (8") and a marker strip above them in the trench (at half trench height) when they were originally run.
I've operated excavators in the past and you always make damned sure of what you are digging into.

I remember back when there were protests against a new 400kV line to Auckland, people were screaming for the lines to be put underground (out of sight, out of mind).
IMO, keep them above ground, at you won't have some guy putting an excavator bucket through them.