The RIB2421SB is widely used in HVAC, lighting, and motor control applications where override functionality is required. With compatibility across 24 Vac/dc, 120 Vac, and 208–277 Vac coil voltages, this relay integrates easily into both low- and high-voltage systems. The manual override switch is useful for service work or testing without requiring control input. This relay’s durable NEMA 1 enclosure and UL certifications make it suitable for commercial building automation projects.
- Relays & Contact Type: One (1) SPST Continuous Duty Coil
- Expected Relay Life: 10 million cycles minimum mechanical
- Operating Temperature: -30 to 140° F
- Humidity Range: 5 to 95% (noncondensing)
- Operate Time: 18ms
- Relay Status: LED On = Activated
- Dimensions: 2.30" x 3.20" x 1.80" with 0.50" NPT Nipple
- Wires: 16", 600V Rated
- Approvals: UL Listed, UL916, UL864, C-UL, California State Fire Marshal, CE, RoHS
- Housing Rating: UL Accepted for Use in Plenum, NEMA 1
- Gold Flash: No
- Override Switch: Yes
- 20 Amp Resistive @ 277 Vac
- 20 Amp Ballast @ 277 Vac (N/O)
- 10 Amp Ballast @ 277 Vac (N/C)
- Not rated for Electronic Ballast
- 10 Amp Tungsten @ 120 Vac (N/O)
- 770 VA Pilot Duty @ 120 Vac
- 1,110 VA Pilot Duty @ 277 Vac
- 2 HP @ 277 Vac
- 1 HP @ 120 Vac
Coil Voltage Input:
24 Vac/dc ; 208–277 Vac ; 120 Vac ; 50–60 Hz
Drop Out = 2.1 Vac / 3.8 Vdc
Pull In = 18 Vac / 22 Vdc
Coil Current:
83 mA @ 24 Vac
47 mA @ 120 Vac
69 mA @ 208–277 Vac
47 mA @ 30 Vdc
![]() |
Functional Devices RIB2421SB Specifications |
- Mounting:
- Enclosed
- Number of Relays:
- 1
- Relay Contact Type:
- SPST-N/O
- Relay Coil Voltage:
- 24 Vac/dc/120 Vac/208-277 Vac
- Contact Ratings:
- 20 Amp