50 Amp Generator Cord and Inlet Box 25FT - Weatherproof Power

In this review the Marsflex 50 Amp generator cord and power inlet box is evaluated for homeowners and RV or backup power users who need a heavy-duty, weatherproof connection. The bottom line: this kit is for anyone who wants a reliable 125/250V, 12500 watt hookup with improved conductivity and a durable exterior. The included inlet box with a flip-open cover and LED indicator plus a 25 ft, 100% copper cord make it a practical choice for seasonal power outages, generator hookups at a cabin, or connecting portable power to a home panel.

Key Features

• 100% copper conductors: provides better conductivity for stable delivery of up to 12500 watts, which reduces voltage drop over the 25 ft run.
• Weatherproof inlet box: the pre-drilled SS2-50P inlet box with a flip-open cover offers NEMA 3R level protection so the connection stays protected from wind and rain.
• Twist-lock and ergonomic plugs: the NEMA SS2-50R twist locking female and NEMA 14-50P male plugs keep the connection secure while the ergonomic finger grip eases plugging and unplugging.
• Durable outer jacket: flame-retardant PVC wrapping makes the cord more wear-resistant and water-resistant for outdoor use and longer service life.
• LED power indicator: the green indicator on the inlet box cap lets you tell at a glance when power is present without opening the cover.
• Flexible mounting options: the inlet box arrives pre-drilled in four directions to allow connections from left, right, bottom, or rear for easier installs.

Who It's For

This product is aimed at homeowners, RV owners, and small property managers who need a robust generator-to-panel connection capable of handling 125/250V circuits up to 12500 watts. It suits people installing a dedicated inlet for backup power or frequent seasonal use where weather exposure is a concern.

It is less appropriate for users who need longer runs than 25 ft, require custom wiring beyond the provided STW 6/3 + 8/1 gauge, or who need an inlet without a twist-lock female configuration. Professional electricians should verify compatibility with local codes during installation.

Pros & Cons

Pros

• Strong conductivity from 100% copper wiring improves power stability for heavy loads.
• Weatherproof inlet box with LED indicator makes outdoor installation practical and easy to check.
• Twist-lock female plug and ergonomic male grip help secure and simplify connections.
• Pre-drilled inlet box provides flexible wiring entry options for straightforward mounting.

Cons

• 25 ft length may be short for some setups that require a longer reach.
• The kit uses the supplied wire gauge and connectors, so installers needing different configurations must modify or replace parts.

Specifications

Length	25 ft
Voltage	125V / 250V
Maximum wattage	12500 Watts
Wire gauge	STW 6/3 + 8/1 AWG
Male plug	NEMA 14-50P
Female inlet	NEMA SS2-50R twist-lock
Certifications	ETL Listed, NEMA 3R protection level

Our Verdict

The Marsflex 50 Amp generator cord and inlet box is a solid value for anyone installing a weatherproof, reliable 125/250V generator connection without needing custom-length cable. Its 100% copper conductors, ETL listing, twist-lock inlet and LED indicator combine into a practical kit for backup power or RV use. Those who need longer runs or alternate connector types should plan accordingly, but for typical outdoor inlet installations this kit covers the essentials well.

Frequently Asked Questions

Is this inlet box suitable for outdoor installation?
Yes. The inlet box is designed to NEMA 3R level protection with a flip-open cover and ETL listing for weather resistance.

Can this cord handle a full 50 Amp load?
Yes. The cord is rated for 125/250V up to 12500 watts and uses STW 6/3 + 8/1 AWG with 100% copper conductors for reliable performance.

Does the inlet show when power is available?
Yes. There is a green LED indicator on the inlet box cap that shows when power is present without opening the cover.