(1) Standard machines for arc welding service must be designed and constructed to carry their rated load with rated temperature rises where the temperature of the cooling air is a maximum of 40°C (104°F) and where the altitude is a maximum of 3,300 feet, and must be suitable for operation in atmospheres containing gases, dust, and light rays produced by the welding arc.

(2) When exposed to the following or other conditions, machines must be designed to safely meet the requirements of the service:

(a) Unusually corrosive fumes;

(b) Steam or excessive humidity;

(c) Excessive oil vapor;

(d) Flammable gases;

(e) Abnormal vibration or shock;

(f) Excessive dust;

(g) Weather;

(h) Unusual seacoast or shipboard conditions.