NEMA Plug & Receptacle Configurations

Every common NEMA wiring-device configuration with its face diagram: the designation before the hyphen fixes the voltage, poles, wires, and grounding; the number after it is the amps; R means receptacle, P means plug, and an L prefix means twist-locking. Straight-blade configurations first, locking families below — with what each one is actually used for. Configurations per NEMA WD-6.

Straight-blade configurations

NEMA WD-6

One row per straight-blade configuration per NEMA WD-6, with its face diagram: rating, poles and wires, grounding, and where it turns up. Each configuration exists as a receptacle and a plug — append R or P (5-15R receptacle, 5-15P plug). Only configurations confirmed across published charts are listed; rarely manufactured variants are excluded.
Config	Face	Rating	Poles– wires	Ground	Where you meet it
1-15		125 V	2P–2W		Two-prong household (legacy, ungrounded)
1-20	plug	125 V	2P–2W		Legacy ungrounded 20 A — made as a plug only
1-30	plug	125 V	2P–2W		Legacy ungrounded 30 A — made as a plug only
2-15	plug	250 V	2P–2W		Obsolete 250 V — made as a plug only
2-20		250 V	2P–2W		Obsolete non-grounding 250 V
2-30		250 V	2P–2W		Obsolete non-grounding 250 V
5-15		125 V	2P–3W	✓	THE receptacle — every household & office wall
5-20		125 V	2P–3W	✓	Commercial / kitchen 20 A circuits (T-slot)
5-30		125 V	2P–3W	✓	30 A at 125 V — uncommon
5-50		125 V	2P–3W	✓	50 A at 125 V — uncommon
6-15		250 V	2P–3W	✓	240 V equipment, window AC
6-20		250 V	2P–3W	✓	240 V 20 A equipment and tools
6-30		250 V	2P–3W	✓	240 V fixed appliances, larger AC units
6-50		250 V	2P–3W	✓	Welders, EV charging
7-15		277 V	2P–3W	✓	277 V lighting circuits
7-20		277 V	2P–3W	✓	277 V lighting circuits
7-30		277 V	2P–3W	✓	277 V lighting circuits
7-50		277 V	2P–3W	✓	277 V lighting circuits
10-20		125/250 V	3P–3W		Legacy non-grounding — rare
10-30		125/250 V	3P–3W		Legacy dryer (pre-1996 installs)
10-50		125/250 V	3P–3W		Legacy range (pre-1996 installs)
11-20		3Ø 250 V	3P–3W		Three-phase machinery, no neutral
11-30		3Ø 250 V	3P–3W		Three-phase machinery, no neutral
11-50		3Ø 250 V	3P–3W		Three-phase machinery, no neutral
14-20		125/250 V	3P–4W	✓	4-wire 20 A — uncommon
14-30		125/250 V	3P–4W	✓	Modern 4-wire dryer
14-50		125/250 V	3P–4W	✓	Range, RV park pedestal, EV charging
14-60		125/250 V	3P–4W	✓	4-wire 60 A — large fixed appliances
15-20		3Ø 250 V	3P–4W	✓	Three-phase with ground
15-30		3Ø 250 V	3P–4W	✓	Three-phase with ground
15-50		3Ø 250 V	3P–4W	✓	Three-phase with ground
15-60		3Ø 250 V	3P–4W	✓	Three-phase with ground
18-20		3ØY 120/208 V	4P–4W		Three-phase wye with neutral, no ground
18-30		3ØY 120/208 V	4P–4W		Three-phase wye with neutral, no ground
18-50		3ØY 120/208 V	4P–4W		Three-phase wye with neutral, no ground
18-60		3ØY 120/208 V	4P–4W		Three-phase wye with neutral, no ground
TT-30		125 V	2P–3W	✓	RV shore power (125 V — not a 240 V outlet)

Face diagrams by Comrade Mmirg via Wikimedia Commons, CC BY-SA 4.0, unmodified. Receptacle faces shown; 1-20, 1-30, and 2-15 exist only as plugs, so their plug faces stand in (marked). The non-grounding 1, 2, and 10 families survive only as legacy replacements — new work uses their grounding successors (5, 6, 14).

Twist-locking families (L series)

NEMA WD-6

Locking configuration families per NEMA WD-6, same reading: every configuration exists as receptacle and plug — L14-30R is the generator-inlet receptacle, L14-30P its cord plug. Locking devices are made in 15–30 A sizes; higher-current connections move to pin-and-sleeve (IEC 60309) devices. No free-licensed face diagrams exist for the locking configurations yet, so this table stays compact.
Family	Rating	Poles– wires	Ground	Configurations	Where you meet it
L1	125 V	2P–2W		L1-15	Non-grounding locking (rare)
L2	250 V	2P–2W		L2-20	Non-grounding locking (rare)
L5	125 V	2P–3W	✓	L5-15 · L5-20 · L5-30	Portable generators, stage/event power (L5-30)
L6	250 V	2P–3W	✓	L6-15 · L6-20 · L6-30	HVAC, machine tools, server PDUs (L6-30)
L7	277 V	2P–3W	✓	L7-15 · L7-20 · L7-30	277 V lighting feeds
L8	480 V	2P–3W	✓	L8-20 · L8-30	480 V single-phase, hot–hot–ground
L9	600 V	2P–3W	✓	L9-20 · L9-30	600 V single-phase, hot–hot–ground
L10	125/250 V	3P–3W		L10-20 · L10-30	Legacy split-phase, no ground
L11	3Ø 250 V	3P–3W		L11-15 · L11-20 · L11-30	Three-phase machinery, no ground
L12	3Ø 480 V	3P–3W		L12-20 · L12-30	Three-phase 480 V, no ground
L13	3Ø 600 V	3P–3W		L13-30	Three-phase 600 V, no ground
L14	125/250 V	3P–4W	✓	L14-20 · L14-30	Generator inlets and cords (L14-30)
L15	3Ø 250 V	3P–4W	✓	L15-20 · L15-30	Three-phase 250 V with ground
L16	3Ø 480 V	3P–4W	✓	L16-20 · L16-30	Three-phase 480 V with ground
L17	3Ø 600 V	3P–4W	✓	L17-30	Three-phase 600 V with ground
L18	3ØY 120/208 V	4P–4W		L18-20 · L18-30	Wye with neutral, no ground
L19	3ØY 277/480 V	4P–4W		L19-20 · L19-30	Wye with neutral, no ground
L20	3ØY 347/600 V	4P–4W		L20-20 · L20-30	Wye with neutral, no ground
L21	3ØY 120/208 V	4P–5W	✓	L21-20 · L21-30	Full wye — events, data centers, distro (L21-30)
L22	3ØY 277/480 V	4P–5W	✓	L22-20 · L22-30	Full 480 Y wye with ground
L23	3ØY 347/600 V	4P–5W	✓	L23-20 · L23-30	Full 600 Y wye with ground

L3 and L4 are reserved, unmanufactured designations and are omitted, as are the Canadian 347 V families (24 / L24).

The pattern underneath the numbers

The whole system compresses to one identity: wires = poles + 1 if grounded, on every family in both tables. Two hots or hot–neutral is 2 poles; add a neutral to a 240 V circuit and it's 3 poles; three-phase wye with neutral is 4 — then the ground, which is never counted as a pole, adds the final wire. That's why 14-50 (3P–4W) can feed a range's 120 V clock while 6-50 (2P–3W) cannot, and why the L21 (4P–5W) is the full three-phase-wye everything-connector that event and data-center distro is built on. Voltage families never intermate — blade geometry physically keys each family so a 250 V plug can't enter a 125 V receptacle, and the face diagrams above show exactly how: rotate a blade, add a T-slot, or turn one blade 90° and you've moved family.

Straight blade or locking?

Electrically, an L family and its straight cousin are the same circuit — L5-30 and 5-30 are both 125 V, 30 A, 2P–3W grounding. The difference is mechanical: locking blades twist in and can't vibrate or tension loose, which is why generators, stage rigs, food trucks, and pump connections spec them. Straight blade wins where cheap, ubiquitous, and quick-disconnect matters. Above 30 A the locking system runs out — big portable power moves to pin-and-sleeve connectors or hardwired terminations, and receptacle circuits themselves still follow the branch-circuit rules (a 20 A receptacle needs a 20 A circuit; the breaker behind any of these comes from the load calc, not the plug face).

Common questions

How do I read a NEMA designation like 14-50R or L5-30P?

Family, amps, then device: the number before the hyphen is the configuration family (which fixes voltage, poles, wires, and grounding), the number after is the amp rating, and the letter is R for receptacle or P for plug. An L prefix means twist-locking blades. So 14-50R = family 14 (125/250 V, 3-pole 4-wire grounding), 50 A, receptacle — the range/RV/EV outlet. L5-30P = locking 125 V grounding, 30 A, plug.

What is the difference between NEMA 14-50 and 6-50?

The neutral. Both are 50 A / 250 V-class grounding devices, but 14-50 carries four wires (two hots, neutral, ground — so it can also serve 125 V loads, which ranges and RVs need), while 6-50 is three wires (two hots and ground, no neutral) — typical for welders and some EV chargers. They are not interchangeable, and a 6-50 circuit has no legal place to land a neutral.

Why did dryers move from 10-30 to 14-30?

The 10-series has no ground: it is a 3-pole 3-wire non-grounding family that let the neutral do double duty as the grounding path. The NEC ended that for new installations in 1996 — new dryer and range circuits use the 4-wire grounding 14-series (14-30 dryer, 14-50 range), with the appliance’s neutral-to-frame bond removed. Existing 10-30 circuits may generally remain, which is why the cords are still sold.

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