If the allowable current rating of a busway is 1400 amps, what is the maximum allowable rating of the overcurrent protection device?

When determining the maximum allowable rating of the overcurrent protection device for a busway, it’s essential to apply the appropriate standards and electrical code requirements. The National Electrical Code (NEC) typically requires that the overcurrent protection device not exceed the rating of the conductors or busway to ensure safe operation.

In this case, the allowable current rating of the busway is 1400 amps. According to NEC guidelines, the maximum rating of the overcurrent protection device should be set based on a fraction of the busway’s rating. Generally, it is common to use a rating of 125% of the busway's allowable current to determine the largest permissible size for the overcurrent protective device.

However, since you are looking for something that is safely below the busway rating, it is typically permissible to use a device rated up to 125% of the bus activity. When calculating this:

• 125% of 1400 amps amounts to 1750 amps, which is not listed as an option.

Thus, selecting a rating below the busway while still providing adequate protection is appropriate. The 1200 amps aligns well within common practices by being a safe operating limit, safely under the maximum capabilities, while still