Marsflex 30A Generator Cord & L14-30 Inlet Box 25FT — 10/4 AWG Copper, NEMA 3R Weatherproof

Marsflex 30 Amp 25FT generator cord and L14-30 power inlet box provide a weatherproof, ETL-listed twist-lock connection for up to 7,500 watts of portable backup power.

This Marsflex kit pairs a 25-foot, 10/4 AWG STW copper generator cord (NEMA L14-30P to L14-30R) with a pre-drilled, NEMA 3R-rated inlet box so you can quickly feed a transfer switch or panel during outages. Built with 100% copper conductors, flame-retardant PVC jacket, and a twist-lock design, the set balances safety, durability, and convenience for temporary or seasonal power hookups.

How does the Marsflex cord support safe generator-to-panel connections?

The cord uses heavy-gauge 10/4 AWG STW copper conductors to minimize voltage drop and heat at 30 amps. Both ends are NEMA L14-30 twist-lock devices so the plug stays secure under vibration and load. The female end includes a locking ring and weather-resistant seal to reduce moisture ingress.

• 100% copper wiring for improved conductivity
• NEMA L14-30P (male) and L14-30R (female) twist-lock connectors
• STW 10/4 AWG jacketed cable rated for 125/250V and 7,500 W max
• Ergonomic grip on male plug and locking ring on female plug

What weather protection does the inlet box provide for outdoor installations?

The Marsflex inlet box is ETL listed and built to NEMA 3R standards to resist rain and wind when closed. It features a flip-open hinged cover and an illuminated green indicator so you can confirm power presence without exposing contacts. Four pre-drilled knockout positions let you route conduit or connect from different directions for flexible installation.

• NEMA 3R-rated metal enclosure with hinged, flip-open cover
• Green indicator light on the cap to show incoming power
• Four pre-drilled entry directions: left, right, bottom, rear
• ETL certified for safety and outdoor use

How easy is this set to install and use during an outage?

Installation is straightforward: mount the inlet box, route cable through your preferred knockout, and twist the locking plug into the inlet when you need power. The twist-lock connectors prevent accidental disconnection, and the 25-foot length provides reach to common generator placement points without stretching. The ergonomic design reduces wrist strain when plugging or unplugging under load.

• Pre-drilled holes speed up mounting and conduit choices
• 25 ft length balances reach and manageability
• Twist-lock keeps the connection secure during operation
• Visible power indicator simplifies status checks

What electrical ratings and maintenance should I be aware of?

The cord and inlet box are rated for 30 amps at 125/250 volts with a maximum wattage of about 7,500 W. Routine visual checks for jacket damage, corrosion on terminals, and a secure inlet cover before storms will help maintain reliable service. Replace the cord if you find nicks, exposed copper, or excessive stiffness from age.

• Voltage rating: 125V/250V, max 7,500 watts
• Wire gauge: STW 10/4 AWG with PVC jacket
• ETL listing confirms tested safety standards
• Regular inspections recommended for longevity

Who is this for: Owners of portable generators, homeowners with transfer switches, RV users, contractors, and anyone needing a safe, weather-resistant 30 amp connection for temporary power. The Marsflex kit is designed for users who want a durable, easy-to-install inlet and a reliable twist-lock cord for emergency backup, seasonal use, or jobsite power distribution.