Square D PowerPact HJA vs JDA: Industrial Breaker Comparison
The Square D PowerPact HJA (H-Frame) and JDA (J-Frame) are both 3-pole industrial molded case circuit breakers rated for 480/600VAC. The key difference is frame size and interrupting capacity. The HJA is the smaller H-Frame (15A–250A, 18–65kAIC) while the JDA is the larger J-Frame (100A–600A, 18–65kAIC). Choosing between them depends on your amperage requirement and panel/switchboard compatibility.
Square D HJA (H-Frame) vs Square D JDA (J-Frame) Comparison
| Feature | Square D HJA (H-Frame) | Square D JDA (J-Frame) |
|---|---|---|
| Frame Size | H-Frame | J-Frame |
| Voltage Rating | 480/600VAC | 480/600VAC |
| Poles | 3 | 3 |
| Amp Range | 15A–250A | 100A–600A |
| AIC (Standard) | 18kAIC (HJA) | 18kAIC (JDA) |
| AIC (High) | 65kAIC (HDA) | 35kAIC (JGA) |
| Physical Size | Smaller footprint | Larger footprint |
| Typical Application | Branch circuits | Feeder circuits |
| Price Range | $200–$800 | $500–$2,500 |
| I-Line Compatible | Yes | Yes |
| Adjustable Trip | Fixed thermal-magnetic | Fixed thermal-magnetic |
| Motor Protection | Up to 250A | Up to 600A |
Frame Size Determines Your Choice
In industrial breaker selection, the frame size is determined by the maximum amperage you need. If your circuit requires 250A or less, the H-Frame (HJA/HLA/HGA/HDA) is the correct choice — it's physically smaller, less expensive, and fits in standard I-Line panelboards. If your circuit requires 251A–600A, you MUST use the J-Frame (JDA/JLA/JGA) because the H-Frame simply doesn't go that high.
Understanding the Catalog Number System
Square D PowerPact catalog numbers follow a consistent pattern: HJA36015 means H-Frame, J-suffix (18kAIC), A-type (standard), 3-pole, 600V, 015A. JDA36250 means J-Frame, D-suffix... wait — actually JDA means J-Frame, standard AIC (18k), A-type, 3-pole, 600V, 250A. The first letter is the frame (H or J), the second letter indicates AIC level (J=18k, L=25k, G=35k, D=65k), and the last digits are the amperage.
When to Choose H-Frame (HJA/HLA/HGA/HDA)
Choose H-Frame when: your circuit is 250A or less, you're protecting branch circuits in an I-Line panelboard, you need the smallest physical footprint, you need 65kAIC interrupting capacity (HDA — not available in J-Frame), or you're replacing an existing H-Frame breaker in a panelboard with H-Frame mounting.
When to Choose J-Frame (JDA/JLA/JGA)
Choose J-Frame when: your circuit exceeds 250A (up to 600A), you're protecting feeder circuits or sub-panel mains, you're protecting large motors (100HP+), or you're replacing an existing J-Frame breaker. The J-Frame is also used as the main breaker in many Square D NQOD and NF panelboards.
AIC Rating Selection
Both H-Frame and J-Frame come in multiple AIC ratings. You MUST select an AIC rating equal to or greater than the available fault current at the breaker's installation point. A fault current study (arc flash study) will tell you the available fault current. For most commercial buildings, 18kAIC (HJA/JDA) or 25kAIC (HLA/JLA) is sufficient. For industrial facilities near utility transformers, you may need 35kAIC (HGA/JGA) or 65kAIC (HDA).
Verdict
The choice between H-Frame and J-Frame is primarily determined by amperage: 250A and under = H-Frame, over 250A = J-Frame. Within each frame, select the AIC suffix based on your available fault current. If you're in the 100A–250A overlap range where both frames work, the H-Frame is preferred for its smaller size and lower cost — unless you need the J-Frame's physical mounting for panel compatibility.
Frequently Asked Questions
Can I replace an HJA with a JDA?
Not directly — they have different physical dimensions and mounting patterns. If your panelboard has H-Frame mounting, you must use an H-Frame breaker. However, if you need higher amperage than 250A, you'll need to upgrade the panelboard to accept J-Frame breakers.
What does the second letter mean in HJA vs HDA?
The second letter indicates the AIC (interrupting) rating: J=18kAIC, L=25kAIC, G=35kAIC, D=65kAIC. So HJA is an H-Frame with 18kAIC, while HDA is an H-Frame with 65kAIC. Higher AIC costs more but is required in high fault current locations.
Are PowerPact H and J Frame breakers I-Line compatible?
Yes, both H-Frame and J-Frame PowerPact breakers are designed for Square D I-Line panelboards and switchboards. They plug directly onto the I-Line bus without additional adapters.
What's the price difference between H-Frame and J-Frame?
H-Frame breakers typically cost $200–$800 depending on amperage and AIC rating. J-Frame breakers cost $500–$2,500. The J-Frame premium reflects the larger physical size, higher amperage capability, and heavier-duty construction.