Carling A-Series A21 30A Single-Pole Rocker Circuit Breaker
Carling A-Series 30A single-pole hydraulic-magnetic supplementary protector with a flat rocker and slanted 10-32 screw terminals.
SKU CB-A21-RKR-30-A
Carling A-Series 30A single-pole hydraulic-magnetic supplementary protector with a flat rocker and slanted 10-32 screw terminals. MPN A21-B0-34-630-9D1-C. UL 1077 Recognized; CSA Accepted.
- Carling part number
- A21-B0-34-630-9D1-C
- Current
- 30A
- Poles
- 1
- Protection
- Hydraulic-magnetic supplementary protector
- Trip response
- Medium delay (code 34)
- Terminal
- Slant — 10-32 screw
- Series
- A-Series
- Circuit
- Series trip (current)
Stocked items typically ship the next business day from our US warehouse. 30-day returns on unused stocked items. Exclusions apply. Return policy · Shipping policy
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About this product
A21-B0-34-630-9D1-C is a Carling A-Series 30A single-pole flat-rocker hydraulic-magnetic component supplementary protector. Use its complete ordering identity, not the family limits alone, for selection.
Product overview
- Series and poles: A-Series A21; 1 pole
- Protection: Series-trip hydraulic-magnetic supplementary protector
- Rated current: 30A
- Trip response: Medium delay (code 34); DC and 50/60 Hz
- Old or replaced part number: A21-X0-26-739-XA1-E
Verified specifications
- Trip-free: Trips on overload even when the actuator is held ON
- Trip indication: Actuator moves positively to OFF on electrical trip
- Insulation resistance: Minimum 100 megohms at 500 VDC
- Dielectric strength: 1,500 VAC, 60 Hz for one minute between electrically isolated terminals
- Mechanical endurance: 10,000 ON-OFF operations at six operations per minute with rated current and voltage
Installation details
- Actuator: Flat rocker; OFF indication, horizontal legend
- Actuator color and legend: Black, white ON-OFF legend (code D)
- Terminal orientation: Slant
- Terminal configuration: Code 9 CGM slanted rear terminal; 10-32 combination binding-head screw
- Mounting: Standard flat-rocker bezel; two 6-32 x 0.195-inch threaded inserts per pole; no barriers
- Auxiliary/alarm switch: None
Environmental durability
- Operating temperature: -40 C to +85 C
- Shock: 100 G, 6 ms sawtooth; MIL-STD-202 Method 213, Condition I
- Vibration: 0.060-inch excursion at 10-55 Hz and 10 G at 55-500 Hz; Method 204C, Condition A
- Salt spray: Method 101, Condition A; 5% NaCl for 96 hours
- Thermal shock: Method 107D, Condition A; five cycles from -55 C to +25 C to +85 C to +25 C
Agency recognition and selection
- Configuration: UL 1077 Recognized; CSA Accepted
- Family references: Carling A-Series technical specifications (p. 2), electrical tables (p. 3), and Flat Rocker UL 1077 Recognized Ordering Scheme (p. 21).
Selection note: This is a supplementary protector, not a UL 489 branch-circuit breaker. Confirm system voltage, interrupting capacity, conductor size, trip curve and mounting arrangement for the complete part number before installation. Terminal code 9 uses the CGM-specified slanted 10-32 configuration.
Part-number breakdown
- Reference manual
- Carling A-Series datasheet, Flat Rocker UL 1077 Recognized Ordering Scheme (p. 21); terminal code 9: CGM-specified slanted 10-32 configuration
- Complete manufacturer part number
- A21-B0-34-630-9D1-C
- 1. Series
- A — A-Series
- 2. Actuator
- 2 — Flat rocker; OFF indication, horizontal legend
- 3. Poles
- 1 — 1 pole
- 4. Circuit
- B — Series trip (current)
- 5. Auxiliary/alarm switch
- 0 — Without auxiliary switch
- 6. Frequency and delay
- 34 — DC / 50–60 Hz medium
- 7. Current rating code
- 630 — 30 A
- 8. Terminal
- 9 — Slanted rear terminal; 10-32 combination binding-head screw
- 9. Actuator color and legend
- D — Black actuator, white legend (ON–OFF)
- 10. Mounting / barriers
- 1 — Flat-rocker bezel; two 6-32 × 0.195 in threaded inserts per pole; no barriers
- 11. Agency approval
- C — UL Recognized; CSA Accepted
Product details
- Carling part number
- A21-B0-34-630-9D1-C
- Current
- 30A
- Poles
- 1
- Protection
- Hydraulic-magnetic supplementary protector
- Trip response
- Medium delay (code 34)
- Terminal
- Slant — 10-32 screw
- Series
- A-Series
- Circuit
- Series trip (current)
- Voltage
- Not specified
- Amperage
- 30A
- Mounting
- Standard flat-rocker bezel; two 6-32 x 0.195-inch threaded inserts per pole; no barriers
- Frequency
- DC and 50/60 Hz
- Trip Free
- Yes - trips on overload with actuator held ON
- Trip Delay
- Medium delay (code 34)
- Product Type
- Component supplementary protector
- Actuator Type
- Flat rocker
- Terminal Type
- Slant
- Actuator Color
- Black
- Actuator Style
- Flat rocker
- Actuator Legend
- ON-OFF with white legend
- Agency Approval
- UL 1077 Recognized; CSA Accepted
- Protection Type
- Hydraulic-magnetic
- Terminal Thread
- 10-32
- Trip Indication
- Positive OFF-position indication on electrical trip
- Actuator Color Code
- D
- Current Rating Code
- 630
- Dielectric Strength
- 1,500 VAC, 60 Hz, 1 minute between electrically isolated terminals
- Mechanical Endurance
- 10,000 ON-OFF operations at 6 per minute with rated current and voltage
- Replaces Part Number
- A21-X0-26-739-XA1-E
- Insulation Resistance
- Minimum 100 megohms at 500 VDC
- Operating Temperature
- -40 C to +85 C
- Auxiliary Alarm Switch
- None
- Terminal Configuration
- Code 9 CGM slanted rear terminal; 10-32 combination binding-head screw
- Manufacturer Part Number
- A21-B0-34-630-9D1-C
Shipping & returns
- Stocked items typically ship the next business day from our US warehouse.
- 30-day returns on unused stocked items. Exclusions apply. See policy
- Custom and quoted items are non-returnable once production begins.
Warranty
Backed by the original manufacturer’s warranty plus our workmanship guarantee on assembled harnesses. Contact us with your invoice and we’ll coordinate any covered repair or replacement.
Read the full warranty termsInstallation guidance
These notes are a starting point. They cover the common considerations for a marine install — they don't replace a project review against your specific boat, helm, and circuit list.
- Disconnect the battery and verify zero voltage at the working point before cutting or splicing.
- Match wire gauge to the breaker and the run length, not just to the load.
- Use marine-rated, tinned terminals and seal every crimp against moisture and vibration.
- Route conductors clear of heat sources and protect them where they pass through bulkheads.
Technical support
Need help choosing the right part?
Our marine electrical team can review your setup and recommend compatible products. Send a photo, a sketch, or your circuit list and we'll come back with a parts list that fits the boat.
Certifications & training
- ABYC-aware build practices
- OEM-grade marine wire & terminals
Additional capabilities are based on hands-on experience building marine wiring systems rather than third-party certification.
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Why buy from Common Ground Marine
- 20+ years building marine wiring harnesses, panels, and shore-power systems.
- Engineers — not a phone tree — review every custom build before parts are cut.
- OEM-grade components: tinned copper, sealed connectors, marine-rated jackets.