An industrial mixer system in a concrete factory is used to create concrete. Concrete is formed by mixing cement, water, additives and aggregate together at highs speeds and temperatures to form a liquid composite that hardens over time. Cement mixers are equipped with hatch doors which are typically accessed in order to clean the inside of the mixer. Such machinery is interlocked and each hatch door is fitted with a mechanical door lock to ensure that operators and/or maintenance personnel can only gain entry once power to the machine has been isolated. All interlocks are constructed from a full stainless steel casing to that have been specifically designed to ensure their continued operation in arduous, dusty environments.