The Enquirer understands that an ongoing ballot of electricians will see more than 90% of sparks reject the current offer.

The result will infuriate contractors who thought they had a deal after the 5% rise over two years was accepted by a negotiating team from the Unite union.

But a wider meeting of shop stewards and activists rejected the offer resulting in the current ballot.

The Electrical Contractors Association wrote to Unite Assistant General Secretary Gail Cartmail earlier this month expressing its “huge disappointment” at the rejection.

The association said: “Our first concern is that negotiations which have been conducted in good faith over a five-month period can be so easily undone by the uninformed views of people who were not actually present during the negotiations.”

One industrial relations expert said: “The ECA have really got the hump about the whole situation so it will be interesting to see what they do now the ballot looks like it’s going against them.”