Philip King, Fletcher investor relations manager, said Ling's contract was not fixed and he had "not indicated any intention of going anywhere".
Binns' new employer, Meridian, is being considered for partial privatisation with Genesis, Solid Energy and Mighty River Power.
Industry experts said Binns' new role could be far bigger than his job at Fletcher if Meridian eventually became a full float, potentially making it a $9 billion company.
Binns replaces outgoing Meridian chief executive Tim Lusk at the state-owned enterprise. Lusk announced his resignation in March after three years in the job.
Binns joined Fletcher Challenge in 1989 and ran Fletcher operations in Australia, Asia, South America, the United States and the South Pacific.
He led some of New Zealand's biggest infrastructure projects and his latest win was the Waterview Connection, wrested from a rival consortium involving Australian- based Leighton Contractors.
He also got Fletcher appointed by the Earthquake Commission as project manager for Christchurch earthquake house repairs in the $10,000-$100,000 range on insured homes.
Binns was behind Fletcher's successful bid to build Eden Park's new South Stand, winning the Victoria Park motorway tunnel job in Auckland, Te Papa in Wellington, Auckland's Sky Tower and the Manapouri second tailrace tunnel.
Jonathan Ling, now Fletcher chief executive, paid tribute to Binns' contribution yesterday.
"Mark has made a very significant contribution to the business, and has been at the forefront of the company's construction activities for a number of years. In addition, Mark has been a committed and valued member of the executive committee, enhancing the general management of the company," Ling said.
Binns will stay on until December and Fletcher has not made an announcement on his replacement.
Binns said yesterday he thought twice about the new job but he was looking forward to moving to Wellington, keeping the family's Parnell house and looking for an apartment to buy or rent in the capital.
"To be honest, I never thought I'd be leaving Fletcher. I worked out that I haven't looked for a job since I was 26.
"I thought, 'Well, I'm 55, I'd probably see my time out at Fletcher.' I still love all the business that I run and the people.
"I never saw anything remotely approaching this job in terms of the challenge and I didn't want to go to Australia.
"You don't leave a business you have been very happy at for 22 years without a lot of soul searching.
"Meridian is obviously very powerful in its own sector. As you'd expect with a job like that, there were headhunters involved," he said.
"Christchurch has featured in my thinking because obviously I got us into that position with the EQC so felt some responsibility for it but we have gone through the establishment phase and we now have 360 people in Christchurch and a good management team."
MARK BINNS
Departing Fletcher Building infrastructure chief executive:
* Grew up in St Heliers, Glendowie College head boy, First XV captain.
* Expanded St Lukes and Shore City malls when he headed Challenge Properties.
* Heads division which owns NZ businesses Fletcher Construction, Fletcher Residential, Firth Industries, Golden Bay Cement, Humes Pipeline Systems, Winstone Aggregates, Concrete Industries.
* Heads Australian-based businesses Rocla Quarry Products and Rocla Pipeline Products.
* Lives in 1880s Parnell house, married to Louise.
* Nickname: Binns The Builder.
