Construction workers at Ferrybridge power station went on strike following a row over fire safety.
The workers, who are contracted to build a new facility at the site, claimed a fire drill proved to be inadequate and many workers could not hear the alarm.
They believed there was a safety risk and walked off the site.
It is understood they were told the alarms would replaced last Thursday and they were then asked to go back to work.
But they claimed they were told they would not be paid for the remainder of the day, when they left the site.
As a result the tradesmen did not return to work and have staged protests outside the site.
HZI, the main contractor building the new site, said: “Following recent discussions on Ferrybridge Multifuel 2 site, HZI, as principal contractor is in full dialogue with senior stewards and the senior full time officials in an attempt to ensure that the workforce return to work in a timely manner under the conditions of the NAECI agreement.
“HZI would like to stress that from the very first day when concerns were raised they have assured and demonstrated that the HSE concerns raised were taken seriously and ensured that systems throughout the site were fully working.
“This has been endorsed by the unions, stewards and senior officials. We look forward to working together to ensure the safe and timely delivery of the project.”
Meanwhile, an engineering firm by the power station said the protests damaging his trade.
Bob Traynor, who owns Grinding Services on Kirkhaw Lane, said strikers blocking the road to the new plant were preventing deliveries from reaching his factory.
He said he was not opposed to the strikers but felt it was inappropriate that his business was affected.