Hammond 1551SNAP and 1551V Enclosures: Tool-Free Housings for Compact Electronics

If you need to house small electronics without managing screws and fasteners, Hammond Manufacturing's 1551SNAP and 1551V series are a practical solution. These ABS miniature plastic enclosures snap together without tools, mount directly to walls through molded slots, and come in seven sizes covering both circular and rectangular profiles. At a 20 mm height for all sizes, these low-profile enclosures can fit into tight spaces and accommodate components like USB connectors and terminal blocks.

Figure 1: A Hammond 1551SNAP Series plastic, general-purpose enclosure. (Image source: Hammond)

Snap-fit Closure Mechanism

Both enclosure series avoid the need for lid screws through a snap-fit design. The enclosure base includes a hinge feature at the rear edge, allowing the lid to pivot up for access. When you close it, the lid snaps firmly into place at the front without requiring any fasteners. This tool-free operation makes sense for prototyping work where you need frequent access to adjust components, swap batteries, or update the firmware through programming headers.

Hammond designed this closure to maximize internal PCB space. Typical screw-secured enclosures require clearance around mounting holes and space for your screwdriver to reach. The snap mechanism removes these constraints entirely. You can open and reseal the enclosure repeatedly during development without accumulating stripped threads or lost hardware.

Both series carry an IP30 protection rating, which prevents contact with objects larger than 2.5 mm. Your fingers and tools cannot reach internal components, but the enclosures provide no sealing against dust or water. If you need environmental protection, Hammond's standard 1551 series with screw-secured lids achieves an IP54 rating for dust and splash resistance, while their 1551W series provides IP68 waterproofing through integrated silicone gaskets.

Keep in mind that material specifications matter for regulatory compliance and fire safety. Both series use ABS plastic molded with a satin texture finish and rounded corners. The material carries a UL94-HB flammability rating, which means that it burns slowly under test conditions but self-extinguishes when the flame source is removed. Hammond designs these enclosures in Canada and confirms full RoHS and REACH compliance for sale in regulated markets.

Multiple Size Options

You can choose from seven distinct sizes, each maintaining a uniform 20 mm external height. This consistent profile provides adequate clearance for board-mounted RJ45 jacks, USB ports, and standard pin headers while keeping the overall footprint compact. The rectangular and square options suit PCBs with orthogonal layouts, while circular models work for symmetrical sensor arrangements or more aesthetic considerations.

Size 1 measures 40 × 40 × 20 mm externally, making it suitable for small modules like Bluetooth Low Energy radios or battery management circuits. Size 2 extends to 80 × 40 mm, which is ideal for longer boards like USB-to-serial converters or single-channel relay modules. Size 3 provides a 60 × 60 mm square profile for balanced layouts, while Size 4 at 80 × 80 mm is useful for larger microcontroller development boards or multi-sensor arrays.

The circular variants offer different diameters at the same 20 mm height. Size 11 at a 45 mm diameter fits compact disc-shaped PCBs. Size 12 at 60 mm provides moderate space, and size 13 at 80 mm matches the largest rectangular option's width. These circular profiles integrate naturally into environments where rounded aesthetics matter, such as consumer products or visible wall-mounted installations.

You can also specify black, grey, or white for any size and series. Hammond appends color codes to model numbers, e.g., BK for black, GY for grey, and WH for white. A complete part number for a black 60 × 60 mm solid enclosure would be 1551SNAP3BK, and a white 60 mm diameter vented version would be 1551V12WH. So, with seven sizes to choose from, as well as two series and three colors, you get 42 distinct part number offerings.

Installing PCBs and Managing Cables

Four PCB standoffs molded into the base rise 4 mm above the interior floor. These posts accept #2 self-tapping screws measuring 3/16 inch long, which thread directly into the plastic to secure your circuit board. Note that Hammond does not include these screws with the enclosure. You'll need to order them separately as accessory pack 1553WTS100 (100 nickel-plated screws), or source equivalent hardware from your preferred fastener supplier.

Standoff positions vary by enclosure size, so you should download Hammond's dimensional drawings for your specific model to verify compatibility with your PCB mounting holes. Keep in mind that the internal usable area runs slightly smaller than external dimensions due to wall thickness and corner radii. For rectangular models, you can expect internal mounting areas ranging from approximately 34 × 34 mm for Size 1 up to 74 × 74 mm for Size 4.

Cable entry uses a 15 mm diameter knockout molded into the enclosure base. You can punch out this thin section with a screwdriver or similar tool for wire access. The knockout location varies by enclosure size, but typically sits near one edge to keep cables away from the PCB center. For applications requiring sealed cable entry, a separate cable gland or silicone sealant around the wire bundle would be necessary.

Wall mounting capability comes built into every enclosure through two oval slots molded into the base. These slots measure approximately 4 × 16 mm and accept user-supplied screws for securing the enclosure to vertical or horizontal surfaces. The oval shape also provides some tolerance for imperfect screw placement during installation. You can mount these enclosures with the lid opening upward, downward, or to either side depending on access requirements or your cable routing preference.

Figure 2: The Hammond 1551V12GY Snap-fit enclosure. (Image source: Hammond)

Vented Models for Ambient Access Applications

The 1551V series adds ventilation slots on all four vertical faces while keeping every other specification identical to 1551SNAP. Hammond explicitly designed these vented models for sensor applications where you need ambient air to reach the measurement devices. Temperature sensors, humidity detectors, pressure transducers, and air-quality monitors all require direct atmospheric contact for accurate readings. The ventilation pattern allows free airflow while maintaining the IP30 finger and tool protection.

Thermal management is a key application category for vented enclosures. Active components like voltage regulators, motor drivers, or high-power LED controllers generate waste heat that must be dissipated. The 1551V's four-sided ventilation promotes natural convection cooling. Hot air rises through upper vents while cooler air enters through lower openings, creating continuous circulation.

Choosing between solid versus vented models will come down to your primary concern. If dust, moisture, or electromagnetic interference poses the greater risk, select a 1551SNAP enclosure. Its solid walls provide better environmental protection and can be further sealed with gaskets if needed. If accurate sensing or thermal dissipation matters more, choose a 1551V model.

Conclusion

The 1551SNAP and 1551V series leverage a precision-molded ABS construction with snap-fit closure to eliminate screw clearance requirements, maximizing PCB real estate and simplifying iterative access during development. Uniform 20 mm profiles across seven form factors support standardized component heights, while integrated standoffs, knockout cable entry, and wall-mount slots enable streamlined mechanical integration. Vented variants further optimize thermal dissipation and sensor exposure without compromising IP30 ingress protection.

Visit DigiKey to explore the complete selection of Hammond enclosures for your next project.