Product Overview
Hubbell Insulgrip 4-Pole 5-Wire Locking Plug, NEMA L22-20P, 277/480V 3-Phase WYE, Unused in Box
Condition
Unused new old stock in original manufacturer's box. Brass blade contacts show no corrosion or wear. Catalog label on unit confirms HBL2521, NEMA L22-20P, 20A 277/480V, 4P5W, Listed 231A, Made in U.S.A. Sourced from legacy electronics supply chain recovery.
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Product Overview
Hubbell HBL2521 is a heavy-duty male Twist-Lock plug from the Insulgrip line, built for 3-Phase WYE power distribution at 277/480V AC. The NEMA L22-20P configuration delivers a 4-pole, 5-wire grounding interface that locks into a compatible L22-20R receptacle with a push-and-twist action - preventing accidental disconnection from vibration, cable pull, or structural movement. Housing is black and white nylon. Contacts are solid brass. Made in U.S.A.
Key Features
- NEMA configuration: L22-20P locking plug
- Voltage rating: 277/480V AC, 3-Phase WYE
- Current rating: 20A
- Wiring: 4-pole, 5-wire grounding
- Horsepower rating: 5 HP
- Wire accommodation: #16 AWG to #8 AWG stranded copper
- Cord outer diameter range: 0.350" to 1.150" (9.0 mm to 29.2 mm)
- Contact material: solid brass blades
- Housing: chemical-resistant black and white nylon
- Terminal screws: #10-32 brass, compatible with Phillips, slotted, and Robertson drivers
- Enclosure rating: IP20 (dust-shielded wiring chamber)
- Operating temperature: -40°C to +75°C
- Insulgrip dual-jaw cord grip directs pull stress away from terminal connections
- Made in U.S.A.
Applications
- Industrial electrician terminating a power cord on heavy machinery - strips the cable, seats conductors into the funnel-shaped wire entries, torques the #10-32 brass screws, and cinches the Insulgrip cord grip before connecting to the panel-mounted L22-20R receptacle.
- Facilities maintenance tech replacing a damaged plug on a large commercial HVAC unit or ventilation fan where a straight-blade plug keeps pulling loose from vibration.
- Equipment fabricator wiring the power input on a new machine build that ships to a facility with standard 277/480V 3-phase WYE infrastructure.
- Maker or shop owner building a custom high-current 3-phase power distribution cord for a machine tool, rotary converter, or phase converter output.
Frequently Asked Questions
What receptacle does this plug mate with?
It mates with a NEMA L22-20R locking receptacle. The L22-20P (plug) and L22-20R (receptacle) are the matched pair for this configuration. No other NEMA locking configuration is compatible.
Does this work on a standard 240V single-phase circuit?
No. The HBL2521 is rated for 277/480V AC on a 3-Phase WYE system. It is not compatible with single-phase circuits or different voltage configurations.
What wire gauge does it accept?
Accepts stranded copper wire from #16 AWG to #8 AWG. Solid core wire is not compatible. The cord outer jacket must measure between 0.350" and 1.150" in diameter for the Insulgrip cord grip to seat correctly.
Is this plug rated for outdoor or washdown use?
No. The IP20 enclosure rating covers the wiring chamber against dust ingress but does not provide moisture or water protection. This plug is rated for indoor dry locations.
Is a wire, cord, or receptacle included?
Not included. This is the plug body only.
An unused Hubbell in the original box is one of those finds that closes a work order the same afternoon it arrives - no sourcing run, no waiting on a distributor backorder. Whoever opens this box next gets a plug that has never seen a circuit. Their job is to change that.
