Detectors and appliances shall be protected from damage by a mechanical guard as long as what condition is met?

The requirement for detectors and appliances to be protected from damage by a mechanical guard hinges on the stipulation that it is listed for the purpose. When products are listed, it indicates that they have been evaluated by a recognized testing laboratory and found to meet specific safety and performance standards for their intended use. This listing ensures that the guard not only fits the detector or appliance appropriately but also maintains the integrity and functionality of the device it is meant to protect.

If a mechanical guard is not listed for that particular application, it could potentially interfere with the operation of the detection or alarm system, thus compromising safety. Therefore, ensuring that a mechanical guard is specifically listed for protecting detectors and appliances is essential to maintaining overall system effectiveness and compliance with safety standards.

While factors like approval from local authority, installation in a non-public area, and non-interference with operation are relevant considerations, they do not replace the necessity for the guard's proper listing. Only a guard that has been validated for use can guarantee that it will not adversely affect the detector or appliance itself.