A low water cut off is required on a steam boiler not under continuous attendance by a certified operator when the rated input is?

A low water cut-off on a steam boiler serves a crucial safety function by ensuring that the water level in the boiler stays above a certain threshold, preventing the boiler from operating dry and potentially suffering catastrophic failure. The requirement for a low water cut-off is necessary when a steam boiler is not continuously monitored by a certified operator, regardless of the rated input of the boiler.

The rationale behind the necessity of a low water cut-off in relation to the rated input is that the potential for unsafe conditions, such as overheating and boiler damage, exists with all steam boilers when unattended. Therefore, a low water cut-off becomes a critical safety device for any steam boiler not under continuous supervision, illustrating the broader safety guidelines in place for steam boiler operation, regardless of specific input ratings.

This requirement, which applies broadly, emphasizes the importance of safety standards across various boiler capacities, addressing situations where unattended boilers could lead to dangerous conditions without necessary protective measures like low water cut-offs. Hence, it is required for any steam boiler rated above 0 BTU, leading to the conclusion that the appropriate response is that a low water cut-off is required at any rated input value.