How it connects
Plug's curved blades (one usually with a bent tip/tab) are pushed into the arc-shaped slots and the plug is turned about 10-15° clockwise; the blades lock behind contacts so it cannot be pulled out. Contact is by spring blades; not sealed.
Male and female halves
Female = receptacle (suffix R; panel/wall-mounted receptacle or in-line cord 'connector'); male = plug (suffix P). This connection is the female receptacle side.
Usually connects to
- NEMA locking plug of the same configuration and rating (e.g. L5-20P into L5-20R)
Common sizes
- L5-20R is 20 A, 125 VAC, with a face roughly 1.5 in across; flush single-gang, panel and cord-end forms are available.
- Other L-series configurations include 15, 20, 30, 50 and sometimes 60 A; 125, 250, 277, 480, 600 or 125/250 V and three-phase ratings; 2-pole/3-wire through 4-pole/5-wire layouts.
- Examples include L5, L6, L7, L14, L15 and L21, with faces roughly 1.5–2 in. Configuration determines compatibility.
Where it is used
generators and transfer inletsRV and marine shore powerindustrial and commercial equipment; industrial and commercial powerdata center PDUsstage/event powerpool pump timers and outdoor equipmentRVs and marine shore power adaptersstage/entertainment and data-center equipment
Variations
- L5-20R configuration
- Other L-series patterns: L5-15R/L5-30R/L6-20R/L6-30R/L14-20R/L14-30R/L21-30R
- Flush receptacle, inline cord body or flanged inlet/outlet; inlet is male
How to recognise it
Round recessed face with 3-5 arc-shaped slots arranged around a circle (one slot often with an L/notch for the ground), moulded text such as 'NEMA L5-20' plus amp/volt rating and often 'LOCK' arrow; mounted on a yoke with screw strap (wall receptacle) or in a cylindrical cord body (connector).
Often confused with
| Confused with | How to tell them apart |
|---|---|
| NEMA straight-blade receptacle (e.g. 5-20R) | Straight-blade slots are straight lines in a rectangular face and the plug pushes straight in; locking has curved slots on a round face and needs a twist. |
| Different L-series configurations (L5 vs L6 vs L14) | Count slots and read the moulded marking; slot spacing/ground position differs so configurations do not intermate. |
| NEMA TT-30 / 14-50 RV receptacles | Those are straight-blade/non-locking; no twist. |
| NEMA L5-15R | 15 A version; ground slot shape/blade widths differ and the L5-15 plug won't mate L5-20R. |
| NEMA L5-30R | 30 A version, larger face; marked 30A. |
Also called
NEMA locking receptacleL-series receptaclelocking connector (cord-end female)e.g. L5-20R, L5-30R, L6-30R, L14-30RL5-20 twist-lock outletTwist-Lock 20A 125V receptacleTurnlok L5-20RL5-20 female connector (cord body)
Good to know
L-series locking connectors have different configurations. L5-20R and L5-30R share a general face style but have different slot geometry.
Design with real parts
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