ampacity
am-PASS-ih-tee
/æmˈpæsɪti/
The maximum current, in amperes, that a conductor can carry continuously without exceeding its temperature rating.
Crucial term in code compliance; exceeding ampacity causes wire insulation to melt or catch fire.
The story behind the word. Coined in the mid-20th century by American electrical engineers by fusing 'ampere' (named for French physicist André-Marie Ampère) with 'capacity' to create a single word for safe current limit.
Word relationships
- current capacity: Current capacity is an informal descriptive phrase; ampacity is the formal trade metric.
Commonly confused with
- voltage: Voltage is electrical pressure; ampacity is maximum safe electron volume flow.
Word family
- ampere (noun): The unit of electric current.
- amp (noun): Informal shortened form of ampere.
Collocations
- ampacity rating
- conductor ampacity
- ampacity derating
- allowable ampacity
Example sentences
- "Bundling twelve copper wires together reduced their ampacity due to internal heat accumulation." Electrical Code Audit
- "Engineers upgraded the wire gauge from 12 AWG to 10 AWG to ensure adequate ampacity for the heavy machinery." Contracting Specification
Memory hook
AMP + CAPACITY = AMPACITY (how many AMPS a wire has the CAPACITY to hold). Maximum safe current capacity.
When not to use
Do not use in casual everyday conversations; it is a strictly professional electrical contracting term.
Fun facts
- Ampacity drops when wires are installed in hot environments like residential attics in summer.
Related words
Explore more words
resistance, conductivity, fuse, flammable, conductor, incandescence
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