No oil supply or return line shall be concealed in a wall, ceiling or partition unless access to the oil supply or return line can be made without what?

The requirement that no oil supply or return line shall be concealed in a wall, ceiling, or partition without ensuring access is vital for safety and maintenance considerations. The correct answer pertains to the necessity of having the ability to access these lines without cutting through existing walls, ceilings, or partitions because doing so could complicate future repairs and inspections. This provision helps ensure that technicians and maintenance personnel can easily access the systems for service, lowering the risk of damage to the structure and improving safety during troubleshooting or emergency situations.

Concealing lines in a way that prevents easy access can lead to significant issues, such as leaks going undetected or maintenance issues being difficult to resolve, which can increase safety hazards and repair costs. The Maine Fuel Code emphasizes accessible installations to uphold standards of safety and efficiency in fuel line management.