The SP21 3-pin waterproof aviation connector is the mid-size member of the SP push-lock circular family, built on a 21 mm nominal shell. It is made for equipment that needs real current - outdoor lighting, solar combiners, pumps, stage gear and mobile machinery - where an SP13 is too small and an SP29 is oversized. The cable plug mates with a panel or rear-nut socket in a quarter-turn threaded coupling, and the dual O-ring plus rear gland deliver IP68 sealing when mated: dust-tight and immersion-safe beyond 1 m.

The 3-pin layout is wired for single-phase AC or DC power runs with a dedicated earth pin, carrying 30 A at 500 V AC through gold-plated brass contacts. Cable entry accepts 6-8 mm or 8-12 mm jackets, and conductors up to 4 mm² (12 AWG) land on solder cups or screw clamps - no crimp tool required. Housings are UV-stabilised PA66/PC rated UL94-V0, with a nickel-plated brass shell version available for higher mechanical abuse.

• 30 A on a 3-pin barrel: thick 4 mm² capable contacts handle pump, luminaire and inverter feeds without doubling up connectors
• IP68 when mated: dual O-ring at the coupling face plus a compression cable gland resist washdown, condensation, salt spray and temporary immersion
• Keyed, non-intermateable 3-pin insert: the shell cannot be closed on the wrong pin sequence, protecting phase and earth wiring during service swaps
• Twist-lock with vibration hold: threaded coupling nut stays tight on AGV, trailer, drone and marine helm harnesses far better than push-pull or bayonet types
• Field-serviceable termination: solder cup or screw clamp accepts 12 AWG; re-openable and inspectable instead of a heat-shrink butt splice
• Panel and inline variants: front or rear panel-nut socket, 2-hole flange and cable-to-cable coupler share one insert, so the same plug fits a faceplate or a mid-harness joint
• No galvanic corrosion: plastic shell isolates dissimilar metals; 60-70% lighter and lower cost than equivalent metal GX21/GX25 plugs

• vs SP13 / SP17: same twist-lock logic, but 30 A and 4 mm² conductors instead of 13 A and 2 mm² - one size up in power, same installation habit
• vs metal GX21 / GX25 aviation plug: sealed to IP68 rather than splash-rated, no rust on deck or in washdown bays, lighter BOM
• vs terminal block in a junction box: tool-free mate and de-mate, keyed polarity, sealed against hose spray, no cover screws to lose
• vs MC4 / solar quick connectors: 3-pin earth continuity and mixed AC/DC use, not a single-pole PV-only interface
• vs RJ45 or USB panel feed: true circular lock with 30 A contacts, survives vibration and repeated cycling without port wear

• Outdoor LED and signage: luminaire power with earth, landscape light chains, streetlight controller faceplates
• Solar and storage: PV combiner auxiliary feeds, charge controller board power, off-grid 12/24/48 V bus taps
• Pumps and water treatment: bilge, booster and dosing pump feeds where the joint sees spray and humidity
• Industrial automation: 24 VDC motor and valve drops, cabinet-to-machine power links, IO junction hand-offs
• Robotics, AGV and drones: tool-side power, battery disconnect, gimbal and payload harness joints
• Marine, RV and trailer: deck lighting, helm power, winch and accessory feeds (fresh-water and splash rated)
• Stage and event: temporary outdoor audio and lighting power, portable monitor and cart battery links

Standard 3-pin set: one cable plug plus one panel-nut socket, gland set to suit your cable OD, solder-cup contacts, CE and RoHS compliant. Pin counts from 2 to 12, metal-shell and cable-to-cable versions available on request. Tell us your cable OD, conductor size and panel cut-out and we will confirm the exact sub-type.