In a submission to the ACT government's workplace safety inquiry, ActewAGL and ACTEW Corporation have called for tender processes to be reformed to include weight given to a contractor's workplace health and safety record, equal to that of the cost and schedule.

Mr Costello said the tender process needed to reward companies that built workplace safety into their bottom line, not penalise them in a highly competitive marketplace.

As head of ActewAGL, which maintains and supplies the ACT's electricity and gas supply, Mr Costello said he was obsessed with reducing the risk to his 900-strong workforce, 350 of whom worked in the field.

In 1999 Actew lost electrical linesman Gary Waters, who was electrocuted on a Hughes substation having spent 11 years with the company, and in 2001 an ActewAGL worker fell seven metres from a ladder while connecting power to a building site in Braddon.

Both incidents resonate with company management to this day, Mr Costello said.

He believed it was timely for the government to call an inquiry - due to report on Friday - not only because of four recent workplace deaths but because safety culture needed to evolve constantly in order to prevent complacency from setting in.

''Safety is not a static thing. It is not a case of 'I've done it, I've got a safe workplace','' Mr Costello said. ''You're dealing with humans and one of the biggest problems we have is you get complacent, you get bored, you cut corners.''

Since his appointment as chief executive of the part-government-owned utility in 2008, Mr Costello has instigated a ''root and branch'' review of safety systems undertaken by Deloittes.

He also hired a specialist director of environment, health, safety and quality, Dianne King - whose background is in defence and who holds a masters degree in occupational health and safety.

Mr Costello said he was acutely aware of the innate dangers of a workplace in electricity and gas supply, ''which is both dangerous to the workers and to the community''.

One of the deaths that sparked the ACT government's inquiry was when 43-year-old Gunning truck driver Michael Booth was electrocuted in March after electricity arced from powerlines to his truck during a gravel delivery. Mr Costello said the accident had come as a huge upset to the company, which spent considerable time and energy warning the public of the dangers of working near powerlines.

Mr Costello said ActewAGL was incorporating new strategies into continuing safety improvements that included paying cash incentives to workers who report ''near misses'' so they could be analysed. He also made a point to meet personally with every worker who suffered an injury requiring them to take time off work to discuss better ways of managing risk. In the last year, three workers lost a day's work and one lost more than five days following an injury.

While Mr Costello said his preoccupation with workplace safety kept him up at night, he also believed improved safety meant better business. ''People seem to think spending money on safety is a cost, but if you run a safe business you make more money and are more productive than if you don't,'' he said.

''The very procedures and processes and organisation which makes for a safe workplace are the very procedures which make for an efficient organisation.''

Meanwhile, ACTEW Water, which is now a separately run utility to the gas and electricity arm, has received cautious endorsement from the Work Safety Commissioner for addressing safety concerns this year at its Cotter Dam enlargement project.

The $400 million project received 40 notices from the safety regulator over a three-month period from December, mainly relating to cranes, formwork and scaffolding. A worker also lost a finger using an electric saw.

Commissioner Mark McCabe said ActewAGL and ACTEW Water had ''relatively good safety records'' and he accepted the Cotter Dam enlargement was a huge and complex site.

''I am pleased to see that a number of issues we identified on site earlier in the year have been resolved,'' he said. ''There are still occasional issues but my perception is the management of safety there has improved considerably.''

ACTEW Water managing director Mark Sullivan said safety had been ''a real focus over the past 12 months with changes to the way we assess risks and hazards every day and on every part of each individual job on the dam. This has resulted in a real improvement and decrease in safety concerns over the course of the year.

''We have racked up well over 2 million man hours on the dam without any critical accidents and with few lost time injuries. Although we are pleased with this achievement, we will never be fully satisfied with our safety record and will continue to strive to improve it.''

Mr Sullivan noted that although relationships between construction companies, unions and the regulator ''can sometimes be strained'', he also believed all groups wanted to assure workers were safe on any job.