Electrical Code…
- Short-Time Duty
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Operation at a substantially constant load for a short and definite, specified time.
- Continuous Duty
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Operation at a substantially constant load for an indefinitely long time.
- Intermittent Duty
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Operation for alternate intervals of (1) load and no load; or (2) load and rest; or (3) load, no load, and rest.
- Periodic Duty
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Intermittent operation in which the load conditions are regularly recurrent.
- Varying Duty
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Operation at loads, and for intervals of time, both of which may be subject to wide variation.
(National Electrical Code® 100-1)