When can a certified hose be used to connect a construction heater to temporary piping?

Using a certified hose to connect a construction heater to temporary piping is appropriate when certain safety measures are in place. The requirement for having a lever handle shut off valve installed upstream of the hose is crucial for ensuring safety and proper operation. This valve allows for quick shut-off of gas flow, which is important in emergencies or maintenance procedures. It prevents potential hazards by ensuring that gas can be quickly stopped from flowing through the hose if any issues arise.

In contrast, the other options do not address safety regulations or practical functionality relevant to using a hose in this context. The length of the hose is not strictly limited to 15 feet, but rather must conform to safety standards and requirements for installation. The idea that a hose can never be used is not accurate as hoses that comply with safety certifications can be safely utilized under the right conditions. Lastly, while the hose needs to be rated appropriately for its intended use, a high-pressure rating alone does not signify its safe application without additional safety features like shut-off valves. Thus, having a lever handle shut-off valve upstream is essential for safe connecting practices.