The worst-hit sites were in London, and included the Millennium Dome, the Royal Opera House and the Jubilee Line Extension.
On Tuesday, all 200 electricians at the opera house walked out. They were joined by all 300 electricians at Southwark and Westminster stations on the JLE. No electricians turned up to work at the Millennium Dome. Other sites around the UK were also hit.
Spokespeople for the dome, opera house and JLE projects said that deadlines were not affected. All three refused to speculate about the impact of any further industrial action.
The strikers are protesting about an AEEU deal that gives electricians a pay rise of 27% over two years. Those taking wildcat action want a 50% pay rise over the same period.
The Electrical Contractors Association and the AEEU have condemned the action. AEEU boss Sir Ken Jackson branded the strike "stupid", and the ECA said it deplored the action.
Electricians on millennium projects and on the JLE have taken industrial action repeatedly, exploiting the immovable deadlines on these projects as leverage to win pay rises.
