QUESTION: What is the method for determining the loading of attachment plugs?

ANSWER:

1. Determine the ampere load. This should be the machine operating in the way it is intended to operate with a typical mechanical or electrical load. This would be the most severe use that the machine would be put to. This would not be a deliberate overload. This is now the nameplate ampere rating.

2. Determine if the load is continuous of non continuous? Rule 8-104 defines what is continuous and what is non-continuous. If the load is on less than 1 hour in a 2 hour period then it is non-continuous.

3. If the load is determined to be continuous, then follow Table 3 in SPE-1000 for maximum continuous loading limitations of the attachment plug.

For example, the "Maximum Continuous Loading" for a 15P is 12 amperes (1440 watts at 120 volts).

The machine should be labeled "Rated 12 Amperes Continuous"

4. If the load is not continuous from rule 8-104 and maximum current does not exceed 15 amperes (1800 watts at 120 volts) and the supply cord ampacity is not exceeded, then the machine can have a 15P attachment plug. The machine should be labeled , "Rated 15 Amperes Non-continuous".

5. If the equipment follows rule Electrical Heating and Cooking Appliances as per rule 26-742 and the attachment plug is 15 amperes, then the wattage can not exceed 1500 watts at 115 volts (13 amperes).

This follows SPE-1000 as well as a number of equipment specs such as Electric Air Heaters C22.2 No. 46, Motor Operated Appliances (Household and Commercial) C22.2 No. 68 and Vacuum Cleaners and Floor Polishers C22.2 No.67.