Glossary
Terms that decide an answer rather than terms that describe one. Each entry gives the definition, the sections that govern it, and a worked figure showing what the term means on an actual circuit.
- AmpacityThe current a conductor can carry continuously in its installed conditions, and why the tabulated figure is rarely the usable one.310.16
- DeratingDerating is the bridge between a clean ampacity table and the raceway, attic, cable tray or junction box the conductor actually lives in.310.15(B)(1)
- Continuous loadContinuous load changes sizing current for conductors and breakers, while voltage-drop math still follows the current that actually flows.210.19(A)(1)
- Terminal temperature ratingTerminal rating is the reason a 90 C insulated conductor often cannot deliver a 90 C usable ampacity on ordinary equipment lugs.110.14(C)
- Demand factorDemand factor explains why a service or feeder calculation can be smaller than the sum of every nameplate without ignoring those nameplates.Article 220
- OCPDOCPD selection has two sides: it must be large enough for the load and small enough to protect the conductor and equipment.Article 100
- Equipment grounding conductorEGC sizing starts from the upstream OCPD rating, then needs another look when ungrounded conductors are upsized beyond their minimum ampacity size.Article 100
- Voltage dropVoltage drop is a performance check that often upsizes long runs after ampacity and breaker protection already pass.Chapter 9 Table 8
- Conduit fillConduit fill is a Chapter 9 raceway-area check for mixed conductor sizes, insulation types, compact stranding and short nipples.Chapter 9 Table 1
- AHJThe AHJ determines the adopted edition, local amendments, permit process, inspection expectations and final acceptance for the work.Article 100