Frequent outages and power surges, the Union observed, were crippling production, causing damage to machines and equipment of the timber mills and in some instances, triggering fire outbreaks.
The Union warned that the situation, if not quickly addressed, could have dire consequences, by way of job losses.
Already, over 10,000 workers in the sector had been thrown out within the past few years due to unreliable power supply and other challenges, it said.
Mr Joshua Ansah, General Secretary of the Union, said they feared most of their members would be forced to go home because of the problem with electricity supply.
Addressing a press conference in Kumasi on Monday, he also expressed dissatisfaction with the manner in which the Electricity Company of Ghana (ECG) had been disconnecting power to timber milling companies in complete disregard for payment schedule arrangements agreed upon by the affected companies and the power provider.
He said this was compounding the plight of the poor worker in the mills.
Mr Ansah called on the management of the ECG to convene a meeting with the wood processing companies to discuss effective ways of dealing with the situation.
He said the sector gave direct employment to over 100,000 people and therefore its contribution to the economy could not be ignored.