WiremanReceptacles and GFCI
GFCI in dwellings
210.8(A)
Bathrooms, garages and accessory buildings, outdoors, crawl spaces, basements, kitchens, laundry areas, within 6 ft of sinks, tubs and showers, and boathouses.
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Reference
Code lookup by topic
Where to look in the code for the questions that come up on the job. Our one-line summaries point you to the section; read the code book for the full rule and its exceptions.
Receptacles and GFCI
GFCI in commercial and other buildings
210.8(B)
Bathrooms, kitchens, rooftops, outdoors, near sinks, indoor wet locations, locker rooms, garages and service bays, and more.
Receptacles and GFCI
GFCI for outdoor equipment outlets
210.8(F)
Outdoor outlets at dwellings, including hardwired HVAC equipment, need GFCI protection (with listed exceptions).
Receptacles and GFCI
AFCI protection
210.12
Most 120 V, 15 and 20 A dwelling circuits feeding outlets in living areas, kitchens and laundry areas. Also for extensions and replacements.
Receptacles and GFCI
Tamper-resistant receptacles
406.12
15 and 20 A, 125 and 250 V receptacles in dwellings and many other occupancies (schools, hotels, waiting areas) must be tamper-resistant.
Receptacles and GFCI
Wet and damp location receptacles
406.9
Weather-resistant receptacles outdoors; in wet locations, an in-use (extra-duty) cover that stays weatherproof with a cord plugged in.
Receptacles and GFCI
Replacing receptacles
406.4(D)
Where no ground is available, the options: a non-grounding receptacle, a GFCI, or a grounding receptacle fed from a GFCI and marked.
Branch circuits
Kitchen countertop circuits
210.11(C)(1)210.52(B)
At least two 20 A small-appliance circuits for kitchen, dining and pantry receptacles.
Branch circuits
Countertop receptacle spacing
210.52(C)
No point along the counter wall line more than 24 in from a receptacle; any counter space 12 in or wider gets one.
Branch circuits
Wall receptacle spacing
210.52(A)
No point along the floor line more than 6 ft from a receptacle; any wall 2 ft or wider counts.
Branch circuits
Bathroom circuits and receptacles
210.11(C)(3)210.52(D)
A 20 A circuit for bathroom receptacles, and a receptacle within 3 ft of each basin.
Branch circuits
Laundry circuit
210.11(C)(2)210.52(F)
At least one 20 A circuit for laundry receptacles, with no other outlets on it.
Branch circuits
Outdoor and balcony receptacles
210.52(E)
Dwellings need receptacles at the front and back, and on balconies, decks and porches that are reachable from inside.
Branch circuits
Service receptacle at HVAC equipment
210.63
A 125 V receptacle within 25 ft of heating, AC and refrigeration equipment, on the same level.
Branch circuits
Continuous loads (125%)
210.19(A)(1)210.20(A)215.2(A)(1)
A load running 3 hours or more: size the conductors and the breaker at 125% of it.
Branch circuits
Small conductor protection
240.4(D)
14 AWG copper on 15 A, 12 AWG on 20 A, 10 AWG on 30 A, unless a specific article allows otherwise (motors, AC equipment).
Wire size calculator →Branch circuits
Multiwire branch circuits
210.4
Shared-neutral circuits need a common disconnect (handle ties or a multi-pole breaker), and the neutral pigtailed, not run through device screws.
Branch circuits
Voltage drop
210.19 Informational Note215.2 Informational Note
Advisory, not required: 3% on a branch circuit or feeder, 5% total.
Voltage drop calculator →Branch circuits
Dwelling load calculation
220.40 onward220.82
The standard method (Part III) or the optional method for one dwelling unit (220.82).
Dwelling load calculator →Wiring methods
Conductor ampacity and derating
310.16310.15(B)310.15(C)(1)
Table 310.16 values, corrected for ambient temperature and adjusted for more than three current-carrying conductors.
Wire size calculator →Wiring methods
Terminal temperature limits
110.14(C)
Use the 60 °C column for 100 A and less (or 14–1 AWG) and 75 °C above, unless the equipment is marked otherwise.
Wiring methods
Torque on terminals
110.14(D)
Where the maker gives a torque value, tighten to it with a calibrated tool.
Wiring methods
NM cable support
334.30
Secure within 12 in of boxes and at least every 4½ ft.
Wiring methods
EMT support
358.30
Secure within 3 ft of each box or fitting and at least every 10 ft.
Wiring methods
PVC support and expansion
352.30352.44
Support spacing grows with the trade size; use expansion fittings where temperature change moves the run ¼ in or more.
Wiring methods
Bends between pull points
358.26344.26352.26
No more than 360° of bends between pull points.
Bending calculator →Wiring methods
Conduit fill
Chapter 9 Table 1Annex C
53% for one conductor, 31% for two, 40% for three or more.
Conduit fill calculator →Wiring methods
Burial depth
300.5Table 300.5
Minimum cover depends on the wiring method and the location: commonly 24 in for direct-burial cable, 18 in for PVC and 6 in for rigid.
Wiring methods
Underground raceways are wet
300.5(B)310.10(C)
The inside of an underground raceway is a wet location: use wet-rated conductors (THWN-2, XHHW-2).
Wiring methods
Fire-rated penetrations
300.21
Restore the fire rating of walls, floors and ceilings you penetrate, using listed methods.
Wiring methods
Cables in attics
334.23320.23
Cables across joists in accessible attics need protection within 6 ft of the scuttle, or wherever there are permanent stairs or ladders.
Boxes and devices
Box fill
314.16
Count conductors, clamps, devices and grounds, and make sure the box volume covers them.
Box fill calculator →Boxes and devices
Ceiling fan and fixture boxes
314.27(C)314.27(A)
Fans hang only from boxes listed for fan support. Boxes in a ceiling at a fixture location must support at least 50 lb.
Boxes and devices
Neutral at switch locations
404.2(C)
Most switch locations need a neutral, so electronic controls can be added later.
Wiring diagrams →Boxes and devices
Switch and breaker height
404.8(A)240.24(A)
The handle at its highest position no more than 6 ft 7 in above the floor or platform.
Boxes and devices
Boxes in wet and damp locations
314.15
Keep water out of boxes and fittings; listed for wet locations where they are.
Lighting
Required lighting outlets
210.70
A switched light in every habitable room, bathroom, hallway, stairway, garage and at outdoor entrances; stairs over 6 risers need switches at each level.
Lighting
Luminaires in clothes closets
410.16
Enclosed or LED fixtures only, with set clearances from the storage space.
Lighting
Recessed lights in insulation
410.116
Use IC-rated fixtures where insulation will touch them; otherwise keep the listed clearances.
Lighting
Lights over tubs and showers
410.10(D)
Within 3 ft horizontally and 8 ft above the tub rim, fixtures must be listed for damp (or wet, if subject to spray) locations.
Services and panels
Working space at panels
110.26(A)
Commonly 36 in deep (more at higher voltages), 30 in wide or the equipment width, and 6½ ft high, kept clear.
Services and panels
Where panels can’t go
240.24(D)240.24(E)240.24(F)
No overcurrent devices in bathrooms (dwellings), clothes closets or over stair steps.
Services and panels
Service disconnect location and number
230.70230.71
At a readily accessible place nearest where the service conductors enter; limits on how many disconnects.
Services and panels
Outdoor emergency disconnect (dwellings)
230.85
One- and two-family dwellings need a readily accessible emergency disconnect outside.
Services and panels
Surge protection at dwelling services
230.67
Services to dwelling units need a Type 1 or Type 2 surge-protective device.
Services and panels
Overhead service clearances
230.24230.26
Minimum heights above roofs, yards, driveways and streets for overhead service conductors.
Services and panels
Available fault current and arc flash labels
110.24110.16
Mark available fault current on service equipment; field-mark arc flash warnings on equipment likely to be worked on energized.
Grounding
EGC size
Table 250.122
Sized from the breaker or fuse ahead of the circuit.
Grounding lookup →Grounding
GEC size
Table 250.66
Sized from the largest service conductor.
Grounding lookup →Grounding
Grounding electrode system
250.50250.52250.53
Bond together every electrode present; rods need 25 Ω or a second rod at least 6 ft away.
Grounding
Neutral-to-ground bond at the service only
250.24(A)(5)250.142(B)
After the service disconnect, keep neutrals and grounds apart; remove the bonding screw in subpanels.
Grounding
Feeders to separate buildings
250.32
Run an EGC with the feeder, keep the neutral isolated, and add a grounding electrode at the building.
Grounding
Transformers (separately derived systems)
250.30
Bond the neutral to ground at one point and run a GEC from there.
Transformers →Equipment
Motor branch circuits
430.6430.22430.32430.52
Conductors at 125% of table FLC, overloads from the nameplate, short-circuit protection from Table 430.52.
Motor calculator →Equipment
Motor disconnect in sight
430.102
A disconnect in sight of the controller and the motor (in sight means visible and within 50 ft), or a lockable one with conditions.
Equipment
AC equipment disconnect and sizing
440.14440.22440.32
Disconnect within sight of the unit; conductors and breaker from the nameplate MCA and maximum OCPD.
Equipment
Transformer protection
450.3(B)
Primary only, or primary and secondary, with percent limits.
Transformers →Equipment
EV chargers
625.40625.42625.54
Individual branch circuit, sized at 125% of the charger rating as a continuous load; GFCI for receptacles.
Equipment
Solar PV
690705.12690.12
Article 690 for the PV system, 705.12 for connecting at a panel (the 120% rule), 690.12 for rapid shutdown.
Equipment
Standby generators and transfer switches
702445702.5
Optional standby systems need transfer equipment so the generator can’t backfeed the utility.
Special
Pools and hot tubs
680.21680.22680.26
GFCI for pumps and receptacles, receptacle distances, and the equipotential bonding grid.
Special
Temporary power
590.4590.6
Construction power: GFCI for personnel on receptacles, and how long temporary wiring can stay.
Special
Hazardous locations
500–516
Classified locations: Class/Division or Zone. Fuel dispensing is 514; spray booths 516.
2023 NEC numbering. Your jurisdiction may be on a different edition or have local amendments: check with the AHJ.