The workers are employed by electrical subcontractor NG Bailey and are working on the new £734m MENSA building at the Atomic Weapons Establishment in Aldermarston, Berkshire.
If any are required to self-isolate due to coming into contact with someone with Covid-19, they are only entitled to statutory sick pay of just £95 a week.
The workers are also in theory entitled to industry sick pay under the Joint Industry Board agreement.
But this is not paid for the first two weeks of sickness, meaning by the time it is payable the isolation period has ended and the worker has returned to site.
The electricians initially approached NG Bailey to seek agreement that an additional payment could be made to allow them to afford to self-isolate but this was rejected.
In response, the workers agreed to establish their own collection system. Each pays £10 a week into the scheme and if a worker is required to self-isolate or develops Covid-19 they are paid £205, which together with the £95 SSP means they receive a total of £300 a week.
Up to 120 workers are participating in the scheme and there are 8-10 workers involved in collecting the workers’ money.
Most weeks the scheme collects around £1,100. The workers have also introduced an electronic card payment system to make collection easier.
In total 16 workers have required support from the scheme, 15 have been required to self-isolate and one developed Covid-19.
Last week, the scheme paid out £900 to workers self-isolating and a total of £6,785 has been paid out since the scheme began in November.
Unite national officer for construction Ian Woodland said: “Our members deserve nothing but praise for establishing this scheme, where they are supporting and protecting each other.
“The excellent work by our members on the Aldermarston site, exposes that employers and the government have failed to ensure that workers who are required to self-isolate or who are displaying symptoms can afford to not go to work to avoid spreading the virus.
“Workers are left with the stark choice of doing the right thing or paying the bills. No one can survive on £95 a week.
“While this is a heart-warming story of workers taking collective action, it should shame construction employers and the government to act and ensure that all workers are better protected.”