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NEC wire sizing
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WireRef is the electrical wire reference for field work: ampacity, grounding, voltage drop, GFCI, and state code guidance with the derating steps most sites hide.

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545+reference pages
50state profiles
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6 AWG copper THHNNEC 2023
Table 310.16, 90C75A
Temp correction (86°F × 1.0)75A
Bundling (≤3 CCC × 1.0)75A
110.14(C) termination limit65A −13%
Usable ampacity65A

Most references stop at 75A from the table. The actual usable ampacity is 65A after the termination limit that most sites skip.

That gap is what WireRef exists for.

Try it with any wire

Pick your state for code-specific info on every page

Quick answers

The questions electricians search most often, answered with NEC references.

What wire for an EV charger?
6 or 4 AWG
6 AWG on 50-60A breaker. 125% continuous load sizing per NEC 210.20. Tesla, ChargePoint, and universal Level 2.
What wire for a dryer?
10 AWG
30A dedicated circuit on 10 AWG copper. New construction requires 4-wire per NEC 250.140.
What wire for an electric range?
6 AWG
50A circuit on 6 AWG copper. NEC 220.55 demand factor reduces load for ranges under 12kW.
What wire for 200A service?
2/0 AWG
2/0 AWG copper or 4/0 AWG aluminum per NEC 310.12 for qualifying dwelling services. Check with your utility for minimum conductor spec.
Does my kitchen need GFCI?
Required
NEC 2023: all kitchen receptacles now require GFCI per 210.8(A)(6), including the fridge outlet.
What wire for a subpanel?
6 AWG
60A feeder to a detached garage: 6 AWG copper. NEC 250.32 requires 4 conductors to outbuildings.

Calculators & tools

Interactive tools that show every step. Click a tab, then launch.

Ampacity calculator

Full derating with temperature correction, bundling, and the 110.14(C) termination limit. See exactly how each factor reduces your usable ampacity.

Open ampacity calculator

GFCI / AFCI by room

NEC 2023 expanded GFCI to more locations than any previous edition. Kitchen was the biggest change.

Kitchen
GFCI AFCI
Since 2023 Expanded
Bathroom
GFCI AFCI
Since 1975 Original
Garage
GFCI AFCI
Since 1978
Outdoor
GFCI
Since 1981
Basement
GFCI AFCI
Since 2020 Expanded
Laundry
GFCI AFCI
Since 2005
Bedroom
AFCI
Since 2002 AFCI only
Crawl Space
GFCI
Since 1990

Full GFCI/AFCI reference with code-year timelines

Code requirements for all 50 states

Every state enforces a different NEC edition with different amendments, licensing requirements, and permit rules. WireRef tracks adoption status, compliance scores, licensing types, reciprocity agreements, and permit requirements for every state.

Browse all 50 statesLicense reciprocity tool
50
State profiles
65
State comparisons
0-100
Compliance scores

Browse the full reference

545+ pages of NEC-sourced electrical reference. Every value cites its code section.

Wire sizing by circuit
What wire for 15A through 400A. Reverse lookup by breaker size.
26 circuits
Ampacity tables
Every gauge and kcmil, copper and aluminum, THHN, XHHW-2, NM-B. Full derating.
97 pages
NEC code reference
Articles 210, 220, 230, 240, 250, 300, 310, 334, 625, 680. Practical interpretation.
10 articles
Project wiring guides
EV charger, pool, generator, subpanel, dryer, kitchen, garage, and more.
34 guides
Appliance wiring guide
Wire size and breaker for 62 appliances: kitchen, HVAC, laundry, tools, outdoor.
62 appliances
Wire comparisons
Copper vs aluminum, gauge vs gauge, Romex vs conduit, GFCI vs AFCI, and more.
62 pages
NEC adoption by state
Which NEC edition does your state enforce? Licensing, permits, compliance scores.
50 states
Breaker wire size chart
What wire for each breaker: 15A through 200A. Copper and aluminum.
8 breakers
Ground wire sizing
EGC and GEC sizing per NEC Tables 250.122 and 250.66.
24 pages
Wire insulation types
THHN, XHHW-2, NM-B, UF-B, USE-2, and 19 more with specs.
24 types
Conduit fill tables
How many THHN fit in EMT, RMC, IMC, PVC per NEC Annex C.
19 tables
Electrical permits
Do you need a permit? Links to all 50 state electrical boards.
State guide
GFCI / AFCI by room
Kitchen, bathroom, garage, outdoor, laundry, basement. Code-year timeline.
11 rooms
Burial depth requirements
Minimum cover for underground wiring per NEC Table 300.5.
Reference
NEC 2026 changes
What changed in the 2026 code cycle. Load calc updates, EV changes, GFCI expansion.
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Why WireRef?

Every ampacity value shows the full derating chain: base rating, temperature correction, bundling adjustment, and the 110.14(C) termination limit that most calculators skip. Every NEC reference links to the specific article and table. Every calculation shows its work.

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Important: For reference only. Not a substitute for a licensed electrician. Electrical work can cause serious injury, death, fire, or property damage if performed incorrectly. Always hire a licensed electrician for electrical work, especially for service upgrades, panel work, and 240V circuits. Values are derived from NFPA 70 (NEC) for educational purposes. Always verify against your locally adopted NEC edition and amendments - local jurisdictions may enforce stricter requirements. WireRef provides reference information only and is not responsible for work performed based on this content. NEC® is a registered trademark of the National Fire Protection Association. Free NEC access via NFPA · OSHA Electrical Safety · Terms of use.

NEC 2023 references verified April 2026