What is the responsibility of the watchperson regarding heating devices used at the construction site?

The responsibility of the watchperson regarding heating devices used at the construction site is primarily to supervise the devices personally. This means that the watchperson must monitor the heating devices to ensure they are being used safely and properly, which is crucial for preventing potential hazards such as fires or equipment malfunction.

Supervising involves maintaining awareness of the devices' status, ensuring that they comply with safety regulations, and confirming that operators are using the equipment in accordance with the manufacturer’s instructions. This oversight is vital in a construction environment where the use of heating devices can pose significant risks if left unchecked.

The other options, while related to the safe operation of heating devices, do not fully encapsulate the watchperson's main duty. Refueling and cleaning are tasks that may not fall under the supervision responsibility of the watchperson and typically require a designated operator or maintenance personnel. Operating the devices directly is not part of the supervisory role, as the watchperson should remain focused on overseeing safety protocols and procedures rather than handling the equipment themselves.