Electricians from across Britain travelled to protest at Ratcliffe on Soar Power in Nottinghamshire on Tuesday of last week.
They demonstrated against the suspension of an elected Unite union shop steward.
He has been off work for several weeks after being suspended by contractor SPIE Matthew Hall.
The steward was at the heart of protests and walkouts against attempts by electrical contractors to tear up the national agreement in construction.
A well attended national rank and file meeting in Liverpool last Saturday called the protest.
The meeting heard that protests are being planned at Heathrow Terminal 2’s Crown House site in London.
This is because Crown House has withdrawn from the workers’ JIB national agreement.