Reliance Controls Generator Inlet Boxes Compared: Which Amp Rating Fits Your Generator?

Best for
Homeowners with standard 30A generators

The Reliance Controls Generators Up to 7,500 (model PB30) is an industry-standard 30 amp generator inlet box designed for outdoor mounting alongside residential or light commercial structures. Engineered to handle generators producing up to 7,500 running watts at 30 amps, this enclosure is constructed from heavy-gauge powder-coated steel that resists weathering, impact, and outdoor wear. It features an integrated NEMA L14-30P male inlet plug, making it directly compatible with standard 30-amp, four-prong twist-lock generator extension cords.

Inside the cabinet, Reliance Controls provides six knockouts, including four combination 1/2-inch and 3/4-inch openings located on the sides, bottom, and back of the enclosure. This versatile knockout placement gives electricians multiple entry angles for running conduit straight through the exterior wall to an indoor manual transfer switch. The unit also incorporates push-in wire connections, simplifying conductor attachment during installation. Homeowners pairing their transfer switch with a mid-sized portable power plant, such as a high-output pulsar inverter generator, will find the reliance controls PB30 matches typical 120/240-volt generator receptacle ratings perfectly.

While the steel enclosure provides rigid structural strength, it gives way to non-metallic alternatives in regions subject to heavy salt spray or intense coastal humidity, where non-metallic resin offers superior long-term resistance to atmospheric oxidation.

• Supports backup generators producing up to 7,500 running watts at 30 amps
• Built with weather-resistant powder-coated steel in a NEMA 3R configuration
• Equipped with an integrated NEMA L14-30P twist-lock inlet plug
• Features six knockout locations including four combination 1/2-inch and 3/4-inch openings

Best for
High-output whole-home generator backup

For high-demand residential backup power systems, the Reliance Controls Non-Metallic Power Inlet Box (model PBN50) provides the heavy-duty current capacity necessary to support larger generators. Rated for 50 amps and up to 12,500 running watts, this 50 amp power inlet box accommodates large portable generators that deliver high starting loads for central air conditioners, well pumps, and electric heating elements. It features a heavy-duty CS6375 inlet configuration designed to connect securely with 50-amp power cords.

The cabinet is molded from durable, raintight, non-metallic material rated NEMA 3R, preventing rust, denting, and corrosion from rain, ice, and exposure. By hardwiring this enclosure through an exterior wall directly into an indoor transfer panel, homeowners maintain a safe physical distance between the generator exhaust and living spaces, preventing dangerous carbon monoxide accumulation indoors. The enclosure is engineered with four combination 1/2-inch and 3/4-inch knockouts, positioned on the sides, bottom, and back to facilitate neat conduit runs.

This high-output model represents the upper limit of the brand’s residential inlet capacity. Homeowners operating generators rated under 8,000 watts will find this model oversized and should look toward 30-amp or 20-amp models that match smaller cord ends without requiring step-down adapters.

• Rated for high-capacity power systems up to 12,500 running watts and 50 amps
• Durable NEMA 3R non-metallic construction that will not corrode or rust
• Fitted with a heavy-duty CS6375 male power inlet connection
• Contains four combination 1/2-inch and 3/4-inch knockouts for flexible conduit entry

Best for
Modest emergency backup up to 5000W

The Reliance Controls Outdoor Backup Power Inlet (model PB20) is engineered for modest backup systems producing up to 5,000 running watts at 20 amps. Constructed from zinc-plated, rust-proof steel, this NEMA 3R rain-tight enclosure is tailored for homeowners who need to sustain critical household loads, such as refrigeration, sump pumps, and lighting circuits, without the bulk or expense of larger electrical gear. The enclosure is fitted with a NEMA L14-20P inlet plug, accepting standard 20-amp twist-lock generator cords.

Installation convenience is a key benefit of this model. The reliance controls PB20 includes a removable front face, providing open access to the interior chassis for wire pulling and conductor termination. Inside, it features push-in wire connections, built-in grounding, and pre-wired internal leads to streamline the setup process. With six knockout holes distributed across the casing, routing conduit through exterior walls into an indoor panel is straightforward. This setup works seamlessly alongside compact units such as honda generators portable models equipped with standard 20-amp twist-lock receptacles.

However, the 5,000-watt ceiling means this unit cannot accommodate larger open-frame generators. If your backup strategy involves running heavy electric loads simultaneously, stepping up to a 30-amp model like the PB30 is necessary.

• Handles backup systems up to 5,000 running watts and 20 amps
• Zinc-plated steel construction with a rain-tight NEMA 3R outdoor rating
• Features a removable faceplate, pre-wired components, and built-in grounding
• Equipped with an integrated NEMA L14-20P twist-lock male plug

Best for
Coastal regions needing 30A capacity

Homeowners seeking a 30-amp connection in harsh outdoor environments will benefit from the Reliance Controls PBN30 30-Amp NEMA 3R. Operating at a 30-amp, 125/250-volt capacity supporting up to 7,500 running watts, this unit matches the electrical specifications of the steel PB30 but swaps the metal casing for UV-stabilized ABS plastic. Finished in a neutral white color, this enclosure will never rust, peel, or corrode, making it ideal for coastal regions or high-humidity climates where painted steel might deteriorate over time.

The reliance controls PBN30 is an approved transfer switch accessory compatible with Reliance Controls Panel/Link manual transfer panels and generator-ready load centers. It utilizes four combination 1/2-inch and 3/4-inch knockouts located on the bottom, sides, and back, giving installers flexible entry options when running wiring through siding or masonry. The NEMA 3R cabinet design ensures rain, sleet, and snow remain outside the electrical chamber, maintaining dry contacts throughout severe weather events.

This model is an excellent choice when corrosion resistance is the primary buying criterion. However, if structural impact resistance against physical strikes or flying yard debris is your main priority, the heavy powder-coated steel casing of the PB30 offers a more rigid alternative.

• Supports backup power up to 7,500 running watts at 30 amps
• Molded from UV-stabilized ABS plastic that eliminates rust and corrosion
• UL-listed NEMA 3R rain-tight design engineered for harsh outdoor environments
• Four combination knockouts supporting both 1/2-inch and 3/4-inch conduit fittings

Best for
20A setups needing extra wiring room

The Reliance Controls Corporation PBN20 20 Amp provides a corrosion-proof, non-metallic alternative for 20-amp, 5,000-watt backup power configurations. Built in a compact black enclosure with a powder-coated finish, this unit is rated for 20A at 125/250VAC and features an L14-20 inlet configuration. It is designed to be installed in open outdoor spaces, safely bridging the gap between an outdoor generator and an indoor transfer switch while keeping exhaust fumes away from the structure.

A notable advantage of the reliance controls PBN20 is its generous internal volume, providing over 100 cubic inches of wiring space. This generous interior makes pulling stiff, heavy-gauge copper wiring significantly easier compared to smaller, crowded junction boxes. The enclosure includes four combination 1/2-inch and 3/4-inch knockouts (one on each side, the bottom, and the back), allowing direct alignment with indoor junction boxes. Its NEMA 3R weather-resistant rating guarantees dependable protection against precipitation and temperature swings.

The PBN20 is optimized for homeowners with smaller generators who prioritize ease of wiring and zero exterior corrosion. It yields to larger units like the PBN30 or PBN50 when household power demands exceed 5,000 running watts.

• Delivers 20-amp, 125/250VAC capacity for generators up to 5,000 running watts
• Spacious non-metallic cabinet with over 100 cubic inches of internal wiring room
• NEMA 3R weather-tight enclosure in a compact black finish
• Equipped with an L14-20 configuration and four combination knockouts

Best for
Single-circuit 120V emergency power

The Reliance Controls Power Inlet Box PB15 represents the most focused, lightweight option in the brand’s power inlet catalog. Rated for 15 amps at 120VAC, this unit is fitted with a NEMA L5-15P flanged male inlet plug. It is designed specifically for targeted emergency power setups where a homeowner only needs to supply electricity to a single dedicated circuit or a small multi-switch panel running basic necessities such as a furnace blower or a refrigerator.

Featuring a traditional compact profile with screw-in installation, the reliance controls PB15 weighs approximately 7 pounds and provides a dedicated outdoor connection point. By utilizing an L5-15P twist-lock connection, it prevents accidental cord disconnections during storms while keeping windows closed against carbon monoxide fumes. Those comparing residential connection systems might also explore a standard ge generator inlet to see how single-voltage boxes differ across brands.

Because the PB15 is strictly a 120-volt, 15-amp inlet, it cannot supply 240-volt split-phase power. Homeowners with dual-voltage generators or multi-circuit transfer panels requiring 120/240-volt current must choose one of the larger 20-amp, 30-amp, or 50-amp Reliance Controls models.

• Rated for 15-amp, 120VAC single-voltage emergency circuits
• Fitted with a secure NEMA L5-15P twist-lock male inlet plug
• Traditional screw-in mounting configuration weighing 7 pounds
• Compact design suited for localized or dedicated circuit backup