The disconnecting means for heating equipment shall have an amp rating not less than what percent of the total load?

The disconnecting means for heating equipment shall have an amp rating not less than what percent of the total load?

• A. 100%
• B. 110%
• C. 125%
• D. 150%

Answer: (C)

Sizing the disconnecting means to handle more than just the running current is the key idea. Heating equipment can momentarily draw more current when it starts, so the switch or breaker that disconnects this equipment must be able to carry that higher current without overheating or tripping. The required rating is not less than 125% of the total load. This means multiply the total running current by 1.25 to determine the minimum rating of the disconnecting means. For example, if the total load is 40 A, the disconnecting means should be rated at least 50 A (and then rounded up to a standard size). Options that propose 100% or 110% would not provide enough margin for startup surges, while 150% is more than what the rule requires.

Sizing the disconnecting means to handle more than just the running current is the key idea. Heating equipment can momentarily draw more current when it starts, so the switch or breaker that disconnects this equipment must be able to carry that higher current without overheating or tripping. The required rating is not less than 125% of the total load. This means multiply the total running current by 1.25 to determine the minimum rating of the disconnecting means. For example, if the total load is 40 A, the disconnecting means should be rated at least 50 A (and then rounded up to a standard size). Options that propose 100% or 110% would not provide enough margin for startup surges, while 150% is more than what the rule requires.