The breakaway contractors are writing individually to the 6,000 strong workforce explaining why they are pulling out of the industry’s JIB pay and conditions agreement and establishing a new grading structure for the industry.

Firms will also alert the Government, major clients and contractors to plans to switch to a new industry agreement from next March.

The action comes as angry electricians plan more protests at key sites against the controversial element of the proposals to introduce a new installer grade below a fully qualified electrician pay rate.

The big employers – Bailey Building Services, Balfour Beatty Engineering Services, T. Clarke, Crown House Technologies, Gratte Brothers., MJN Colston, SES and SPIE Matthew Hall – argue their a new agreement is needed to reflect modern working practices.

A spokesman for the eight employers told the Enquirer: “There has been a lot of misleading information bandied around about the proposals. Claims that rates will be cut by 35% are nonsense.

“We will not be regrading anybody or changing anyone’s pay rates on site. The new installer grade will only be applied to people joining the industry.”

He added: “When the people see our proposals for themselves, we are very confident they will understand and support the changes.”

Individual copies of the draft Building Engineering Services National Agreement -BESNA – are to be sent to every worker affected by the new grading structure plan.

Contractors have been trying for four years to revamp archaic pay practices which have been overtaken by technology and working practices.

The distinction between M&E contractors has blurred in recent years with contractors offering single point integrated skills as building services contractors. But the industry has remained locked into two separate wage agreements.

Growth in prefabricated electrical components has meant much work on site requires straight forward assembly skills.

But the existing JIB deal means work still has to be carried out by a fully qualified electrician paid an hourly rate of more than £16.

The contractors’ spokesman said: “There really is no alternative. Contractors need greater flexibility to build a workforce with the appropriate skills and appropriate numbers.

“They have to bring in this reform if they are to survive in the modern building environment.

“That is why they have no choice but to go directly to their staff.”

He added: “Nobody wants to be forced into going down the labour agency or subcontractor path to do these jobs. It isn’t about de-skilling, its about properly manning projects from within, rather than with subcontractors.”

Union leaders at Unite claim the new grade will undermine skilled electricians and lead to de-skilling.

More than 500 rank-and-file sparks voted to take part in unofficial action during a stormy meeting in London two weeks ago.

Since then protests have been staged at N G Bailey sites and Balfour Beatty’s high-profile Blackfriars station project in London.

Discussion between the employers and Unite ended without agreement last week.

The employers have asked the unions to details their objects to the proposals. “Employers want to discuss and negotiate with trades unions, but we are not making any progress,” said the contractors spokesman.