If you’ve ever stood behind an RV at a campground, waiting for it to hook up to power, you’ve probably glanced at the thick cable snaking between the RV and the pedestal and wondered: “How did that get sized that way?” As a feeder cable supplier who’s worked with RV techs, campground owners, and full-time RVers for over a decade, I get these questions all the time—especially around 50 amp RV setups, which are one of the most common upgrades for larger travel trailers, fifth wheels, and Class A motorhomes. Feeder Cable
Let’s cut through the noise: a 50 amp RV doesn’t just need any cable. It needs a cable sized to handle the electrical load, keep your rig safe, and avoid the kind of heat damage that can turn a weekend trip into a costly emergency. Too small, and you risk voltage drops, overheating, even fires. Too big, and you’re wasting money on material you don’t need. Today, I’m breaking down exactly what size feeder cable works for 50 amp RVs, why it matters, and what I recommend after years of seeing what holds up on the road.
First, let’s clarify what “50 amp RV” actually means. A lot of people hear “50 amp” and assume it’s a single 50 amp circuit, but that’s not how RV electrical systems work. Most modern 50 amp RVs are 240V split-phase systems. That means they have two 120V legs, each rated at 50 amps, totaling 10,000 watts of power (50 amps x 200V, if we’re doing the math). You use one leg for your air conditioner, microwave, and outlets, and the other for your water heater, refrigerator, and charging stations. So when we talk about feeder cable for a 50 amp RV, we’re not just sizing for 50 amps total—we’re sizing for the continuous load that will run through that cable.
That brings us to the NEC: the National Electrical Code, the rulebook that governs all electrical installations in the U.S. (and is referenced in most other countries for RV and campground power). NEC rules are non-negotiable here. For continuous electrical loads—like the ones your 50 amp RV will pull (your AC runs for hours, your fridge is on nonstop)—the code requires that feeder cables are sized to handle at least 125% of the load. For a 50 amp RV, that means 50 amps x 125% = 62.5 amps. That’s the minimum current your cable needs to handle without overheating.
Now, let’s translate that into cable gauge. Cable gauge is the measure of a wire’s thickness; the lower the number, the thicker the wire. For copper wire, which is the most common and durable for RV use, let’s go over the numbers that apply here. I’ve seen a lot of campgrounds and RVers cut corners with a 6 gauge cable for 50 amp setups, but that’s a mistake. For 600V copper feeder cable (the standard for RV power), the ampacity (the amount of current a wire can safely carry) is roughly:
- 6 gauge copper: 55 amps
- 4 gauge copper: 70 amps
Wait, that’s a big gap. Let’s go back to that 125% rule: we need the cable to handle 62.5 amps. 6 gauge only does 55, which is 7.5 amps short of the minimum required. That means if you run a 6 gauge cable for a 50 amp RV, you’re operating it at 50 amps, which is 9% over its rated ampacity. Over time, that extra load will cause the wire to heat up, insulation to degrade, and eventually, you could have a fire hazard. That’s why NEC doesn’t allow that for permanent feeders, and why as a supplier, I warn customers against it every time.
What about aluminum cable? A lot of people ask about aluminum, because it’s cheaper, lighter, and works for some applications. But here’s the catch for RV feeders: aluminum has a lower ampacity than copper. 6 gauge aluminum only carries about 45 amps, 4 gauge aluminum carries 60 amps. So even a 4 gauge aluminum cable is barely touching that 62.5 amp minimum. It’s not enough for continuous loads, and it also requires special termination fittings to prevent corrosion and connection failure—something most RVers don’t account for. I don’t recommend aluminum for 50 amp RV feeders unless it’s absolutely necessary, and even then, a lot of campgrounds won’t approve it for permanent hookups.
Now, what about different lengths? That’s another big factor most people miss. The longer the cable, the more voltage drop you’ll get, and you’ll need a thicker gauge to compensate. Voltage drop is the amount of power lost as electricity travels through a wire. For RVs, NEC recommends a maximum voltage drop of 3% from the pedestal to your RV’s electrical panel. If you go over that, your appliances won’t run right—your AC might blow weak air, your fridge could cycle on and off constantly, and your battery chargers won’t work properly.
Let’s do a quick example. If you have a 50 amp RV, a 10 foot cable run. Let’s calculate voltage drop for 4 gauge copper: at 50 amps, a 10 foot run will have a voltage drop of roughly 0.8%, which is way under 3%—perfect. Now, if you have a 50 foot cable run, that same 4 gauge copper will have a voltage drop of about 4%, which is over the 3% limit. So for a 50 foot run, you need to go up a gauge: 2 gauge copper, which will bring the voltage drop down to 2.2%, right under the code limit. For a 100 foot run, you’ll need even thicker: 1 gauge copper, which will give you a 2.8% voltage drop. For anything longer than 100 feet, most experts recommend either 1/0 gauge copper or two parallel cables, but that’s a special case for very remote campgrounds or off-grid setups.
I’ve heard too many stories from customers who saved a few bucks on a smaller cable, only to have to replace their entire RV’s electrical system a year later, or worse, have a fire at their campground site. Last year, a customer in Florida came to me after his 6 gauge cable overheated during a 3-day heatwave, melting the insulation right at the pedestal and nearly starting a fire. He told me he thought 50 amp meant he could use a 6 gauge, no questions asked. That’s exactly why I spend so much time walking through this with anyone who buys a feeder cable from me—because a little knowledge goes a long way.
Now, let’s talk about the types of cable you should look for, too, not just the gauge. RV feeder cable is different from regular house wire. It’s designed to be flexible, weather-resistant, and rated for outdoor use. The most common type is SOOW cable (Synthetic Oil-Resistant Outer jacket, Oil-Resistant insulation, Weather-resistant). SOOW is perfect for RV setups because it can handle extreme temperatures, rain, UV rays, and the occasional tug or twist from moving the RV. Avoid indoor ROMEX wire for this—ROMEX isn’t rated for outdoor use, and it will degrade fast when exposed to the elements, leading to frayed wires and safety hazards.
Some customers also ask about 50 amp extension cords vs. feeders. Wait, is there a difference? Yes, and it’s important. A feeder cable is a permanent or semi-permanent run between the campground’s pedestal and your RV, usually up to 100 feet. An extension cord is for temporary use, like if you need to extend your connection a bit at a campground. But the sizing rules still apply: even an extension cord for a 50 amp RV needs to be the right gauge for its length. A 25 foot extension cord can get away with 6 gauge, but any longer than that, and you need to go to 4 gauge, same as a feeder.
Let’s summarize what you should take away for a standard 50 amp RV setup, assuming a 10 to 50 foot cable run (the most common range for most campgrounds and private properties): the correct size feeder cable is 4 gauge copper. That checks all the boxes: it meets NEC’s 125% load requirement, it has a low enough voltage drop for runs up to 50 feet, it’s durable enough for RV use, and it’s priced reasonably compared to thicker gauges. For runs between 50 and 100 feet, go with 2 gauge copper. For runs over 100 feet, contact a professional to confirm, but 1 gauge copper is the standard go-to.
Now, I know there are a lot of options out there, and it can be overwhelming to pick the right one. That’s where I come in. As a feeder cable supplier, I don’t just sell wire—I make sure my customers get the right size for their specific setup, no guesswork. I’ve worked with full-time RVers who take their rig cross-country, small campgrounds updating their hookups, and even large RV parks expanding their sites, and I can help you figure out exactly what you need, whether you’re dealing with a 10 foot run or a 100 foot remote setup.
If you’re in the market for a 50 amp RV feeder cable, or have questions about sizing, voltage drop, or the right type of cable for your rig, don’t hesitate to reach out. I’m always happy to walk through the details with you, make sure you get something safe, reliable, and tailored to your needs. No one should have to stress about their power on the road, and the right feeder cable is the first step to a smooth, worry-free trip.
High Temperature Cable Connector References
- National Electrical Code (NEC) Article 551, “Recreational Vehicles”
- American Wire Gauge (AWG) Ampacity Tables, Copper Conductor, 600V
- RV Safety Foundation, “Electrical Safety Guidelines for Recreational Vehicles”
- Federal Emergency Management Agency (FEMA), “Electrical Hazard Prevention for Recreational Vehicles”
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