DC-022B: 5.5×2.1mm Barrel Jack with Waterproof Jacket for Panel Mount Enclosures

Barrel connectors come in a long list of sizes, and the combination of a 5.5mm outer diameter and a 2.1mm center pin is the one most wall adapters and bench supplies use. The DC-022B is a 5.5 x 2.1mm barrel connector in jack form, meaning it is the female side that stays on the product and receives the plug from the power supply. It is a panel mount part: it goes through a hole in the enclosure wall and is fixed from there, so the power port sits on the outside of the product while the wiring stays inside.

What separates it from an ordinary panel jack is the waterproof jacket fitted around the barrel opening. On a standard jack there is a small gap where the connector body meets the wall, and the barrel itself is open whenever no plug is inserted. Rain, spray, or washdown water that reaches that gap can run along the connector and into the housing. The jacket closes the gap between the connector and the panel, which is the most common path for water into an otherwise sealed enclosure.

5.5×2.1mm Barrel Jack with Waterproof Jacket: Who It Is For

This part makes sense when the power port is exposed: outdoor controllers, boat and marine accessories, equipment in washdown areas, and enclosures installed where dust and moisture are routine. It is not the cheapest way to add a power input. If your enclosure lives indoors and stays dry, a standard 5.5*2.1 DC jack installs the same way and does the job for less.

Check the current before you commit. The DC-022B is rated 0.5A, which suits low-power devices such as sensors, small controllers, and indicators. Many 5.5×2.1mm power adapters are built for one to three amps, and a jack rated for 0.5A should not be used as the power path for a load that draws more than that.

The values below come from the product listing. This 5.5 x 2.1mm female connector is specified for DC 30V and 0.5A.

DC-022B 5.5×2.1mm Barrel Jack: Rating Summary

When you choose a 5.5 x 2.1mm DC power jack socket for a sealed enclosure, the jack is usually the weakest point in the seal. The features below are the ones that decide whether it stays dry and keeps working after months of plugging and unplugging.

A note on water protection: the term “waterproof” on a connector listing does not by itself say how much water the part can take. Ingress protection is normally stated as an IP code, defined in IEC 60529, and the first digit (dust) and second digit (water) mean very different things. If your design needs a specific rating, ask for the test report before you finalize the enclosure. Material compliance follows RoHS requirements; ask us for the declaration if you need it for a customer file.

A DC 30V rating on this 5.5 x 2.1mm DC jack covers most 5V, 9V, 12V, and 24V supplies, so voltage is rarely the limit. Current is. With a 0.5A rating, the DC-022B fits low-power equipment, and the examples below are all in that range.

The two most common barrel sizes share the same 5.5mm outer diameter and differ only in the center pin: 2.1mm or 2.5mm. The 0.4mm difference is easy to overlook and hard to see by eye. A 2.1mm plug in a 2.5mm jack makes poor contact and drops out when the cable moves, while a 2.5mm plug often will not enter a 2.1mm jack at all, or enters by force and damages the contact. Both situations show up as returns after the product has shipped.

Measure the plug on your supply with calipers before choosing the jack, and do not rely on the label alone, since “5.5×2.1” is sometimes printed on plugs that measure differently. Our 5.5×2.1mm vs 5.5×2.5mm selection guide walks through the measurement, and the DC barrel jack connector guide covers the other common sizes. For power-path sizing and derating, see barrel jack connectors for power supplies.

Polarity is not set by the jack. Whether the center pin is positive or negative depends on how the terminals are wired and how the supply is built, so confirm both before powering anything. If you need a jack that solders onto a PCB instead of mounting through a panel, the vertical DIP DC jack and the 90-degree DIP DC jack are options; check the barrel size on each page, and browse the full range of DC power jack sockets if you are still choosing.