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| Cord | Price | Notes |
|---|---|---|
| 50 A NEMA 14-50 cord, 6 AWG, 15 ft | $80 – $130 | Straight-blade, common on larger inverter and portable generators |
| 50 A SS2-50 (CS6364) twist-lock cord, 6 AWG, 25 ft | $130 – $220 | Locking connector preferred for permanent inlet pairing |
| 50 A cord, 6 AWG, 50 ft | $180 – $250 | Longer runs add voltage drop; size up only with reason |
| L14-30 (30 A) cord, 10 AWG, 25 ft | $60 – $110 | For 30 A generators; do not use on a 50 A inlet |
| Power inlet box (14-50R or SS2-50) | $40 – $120 | Wall-mounted, weatherproof; installed by an electrician |
The amperage math: what 50 amps actually means
A 50-amp, 240-volt connection delivers up to 12,000 watts: 50 A x 240 V = 12,000 VA. That is the headline number that makes 50-amp cords attractive for running a meaningful slice of a house. But the rating is the ceiling, not a promise: your generator only delivers what its engine and alternator can produce, and many "50-amp" portable generators actually peak around 7,500-9,500 watts running. Working out what size generator you actually need tells you whether a 50-amp cord even matters for your loads. The 50-amp outlet and cord simply let the unit pass its full output without the connector becoming the bottleneck.
Because the cord may carry the full 50 amps continuously, conductor sizing is not negotiable. The 80 percent continuous-load convention in NEC 210.19 and the ampacity tables in NEC 310.16 put a 50-amp circuit on 6 AWG copper. Smaller wire on a 50-amp connector is a fire waiting for a sustained load: the connector says 50 amps, the thin wire overheats inside its jacket, and nothing trips until the insulation fails. If you build or buy a 50-amp cord, confirm it is 6 AWG copper end to end.
Aluminum cords exist but require upsizing (typically to 4 AWG aluminum for 50 amps) and are uncommon in flexible generator cordage, so treat 6 AWG copper as the default and read the jacket print to verify both gauge and conductor count (a 240-volt cord carries four conductors: two hots, neutral, and ground).
Plug types: 14-50 vs SS2-50 twist-lock vs L14-30
The NEMA 14-50 is a straight-blade, four-prong 50-amp, 240-volt receptacle, the same one used for ranges and EV chargers. Many larger portable and inverter generators put a 14-50R on the panel, so a 14-50 to inlet cord is a frequent pairing. Straight blades are easy to plug in but can be vibrated or tugged loose, which is why permanent installations often prefer a locking connector at the generator end.
The SS2-50, sold under designations like CS6364 (plug) and CS6365 (receptacle), is the 50-amp twist-lock standard on many generators built for backup duty. You insert and rotate, and the connector mechanically locks so it cannot vibrate loose under engine running or be pulled out by the cord's weight. If your generator has an SS2-50 outlet, match it: do not adapter-hack a straight blade onto a twist-lock circuit, because adapters add failure points exactly where 50 amps is flowing.
The L14-30 is a different animal: a 30-amp, 240-volt twist-lock good for 7,200 watts (30 A x 240 V), and it is the right connector for the very common 30-amp portable generators. People conflate it with 50-amp gear, but it is not interchangeable. Putting an L14-30 cord on a 50-amp inlet under-protects nothing dangerously by itself, but it caps you at 30 amps and invites adapter chains. Buy the cord that matches the generator outlet and the inlet box, full stop.
Cord gauge and length limits
For 50 amps, 6 AWG copper is the floor for short runs. Length matters because voltage drop scales with distance: the farther the generator sits from the inlet, the more voltage the cord eats, and at 240 volts a long, undersized cord can starve motor loads and overheat. As a rule of thumb, 6 AWG holds acceptable drop (under 3 percent) for 50-amp runs up to roughly 50 feet. Past that, you step up a gauge to 4 AWG to keep the voltage at the panel where it belongs.
Resist the urge to daisy-chain cords or add a long extension to reach a convenient generator spot. Each connector is a resistance and heat point, and a 25-foot factory cord at the correct gauge beats two 50-foot cords coupled together. If your only safe generator location is far from the inlet, the answer is a single, correctly gauged long cord (and an electrician who can advise on conductor size for the distance), not a chain of whatever is in the garage.
Keep cords uncoiled while running at load. A tightly coiled cord under 50 amps traps heat the same way a coiled extension cord does, and the rating assumes the cord can shed heat to open air. Lay it out, keep it out of standing water, and protect it where it crosses a doorway or driveway.
Inlet box pairing and the transfer switch
The cord is only one link. The other end plugs into a power inlet box: a weatherproof, wall-mounted male inlet (a 14-50 or SS2-50 inlet to match your cord) that feeds the generator's power into the home through a transfer switch or interlock. The inlet box and the transfer mechanism are permanent, code-governed wiring, and that part is licensed electrician territory under NEC 702 (optional standby systems). The cost to hook a generator up to a house covers the inlet and interlock install, and transfer switch installation pricing breaks out the switch itself. The transfer switch or panel interlock physically prevents the generator from back-feeding the utility line, which protects line workers and your generator both. The details of how transfer switch wiring connects explain why that interlock is mandatory.
Match the inlet to the cord and the cord to the generator, as one set. If your generator has an SS2-50 outlet, you want an SS2-50 inlet box and an SS2-50-to-SS2-50 cord (or SS2-50 to whatever the inlet uses), with no adapters in the chain. Mismatched connectors are the most common reason a "complete" generator kit fails inspection or arrives needing an adapter that defeats the locking feature.
What NOT to do: suicide cords and back-feeding
A "suicide cord" is a cord with a male plug on both ends, used to back-feed a generator into a dryer or range outlet. It is named for exactly the reason you would guess. The moment one end is energized by the generator, the exposed prongs on the other end are live: anyone who touches them is across 240 volts. Worse, back-feeding through an outlet bypasses any transfer switch, so the generator can push power back onto the utility lines and electrocute a lineman working to restore your neighborhood, or backfeed and destroy your generator when utility power returns.
There is no safe version of this. The correct, code-compliant way to connect a portable generator to a house is a properly installed inlet box plus a transfer switch or listed panel interlock, fed by a cord with the right connector on each end and 6 AWG copper for 50 amps. Spend the money on the inlet and interlock once; it is the difference between a backup plan and a hazard. If you are unsure how your generator should tie into your panel, have a licensed electrician install the inlet and transfer equipment.
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