The Health & Safety Executive (HSE) prosecuted Birmingham firm RVB Investments UK Ltd and manager Clifford Leigh following the incident on 10 August 2010.
Telford Magistrates' Court heard how RVB employees Eamonn Osborne, 53, and David Rawlins, 46, had been told to find an underground water leak at an empty industrial unit owned by the company at Halesfield 5, Telford.
Mr Leigh instructed them to dig at a spot outside the unit.
Using an electrical drill, they drilled nearly 40cm into the ground until they hit a live 1,000 volt cable. They were engulfed in a fireball and suffered burns to their hands, arms and faces. Both were airlifted to hospital and Mr Osborne was so seriously injured that for the first few days, doctors believed he might not survive.
The court heard that the estimated power of the fireball was equivalent to 4.3 million watts of energy. The heat was so intense that part of the electrical breaker's metal tool was vaporised and a 500 amp fuse was blown in a nearby electrical substation.
HSE's investigation into the incident found that RVB had not assessed the risks involved, devised a safe system of work or obtained site plans of the area, checked whether there were any electrical cables underground or used safe digging methods. The two men had also received no training about the dangers arising from underground services.
The court also heard that in issuing instructions to the two men, Clifford Leigh had a duty to take reasonable care for their safety. Despite being aware of guidance that details how to dig safely near underground services, he failed to ensure that proper precautions were taken before telling them to start work.
RVB Investments UK Ltd, of Hurst Street, Birmingham, pleaded guilty to breaching Section 2(1) of the Health and Safety at Work etc Act 1974. The company was today fined £10,000 and ordered to pay £4,420 costs.
Clifford Leigh, of Longbridge Lane, Birmingham, pleaded guilty to breaching Section 7(a) of the Health and Safety at Work etc Act 1974 and was fined £2,000 and ordered to pay £1,000 costs.
Speaking after the hearing, HSE principal inspector Nic Rigby said: "As this case demonstrates, hitting a live electrical cable is a very real danger and can easily result in deaths or serious injuries.
"Companies must take measures to protect workers who are digging into the ground, where gas and electricity services may be found. They must obtain site plans from service providers, use a cable avoidance tool to scan and check what is actually under the surface, and ensure that workers are properly trained and digging is carried out safely.
"All employees, such as Clifford Leigh, have a responsibility to ensure that they take reasonable care for the safety of their fellow employees when making decisions about how work should be carried out.
"RVB Investments UK Ltd and Clifford Leigh failed to do this and as a result two men were seriously injured in an avoidable incident that could easily have been fatal."