Direct Answer
A 30-amp RV service delivers a maximum of 3,600 watts through a single 120-volt leg. A 50-amp RV service delivers a maximum of 12,000 watts through two separate 120-volt legs. The difference is not a simple 30-to-50 ratio: it is a 3.3x difference in watt capacity that comes from the 50-amp service having two independent power legs, each capable of supplying 6,000 watts on its own.
This page covers the electrical architecture behind each service, what that means for what you can run simultaneously, how adapters do and do not work, and how to use the RV load calculator to find the number that applies to your specific rig.
What This Page Covers (and What It Does Not)
This is the shore power overview. It explains why the capacity numbers are what they are and helps you identify your service type. It does not cover:
- How to choose or use a surge protector or EMS at each pedestal type: see 30-amp EMS at a 50-amp pedestal
- The difference between an EMS and a basic surge protector: see EMS vs surge protector
- Your personal load total: use the RV load calculator
The Electrical Architecture of Each Service
30-Amp Service: One Leg, One Hot Conductor
A 30-amp RV shore power connection uses the NEMA TT-30 configuration: two-pole, three-wire, rated at 30 amperes and 125 volts AC (manufacturer requirement: Leviton 7313 TT-30R specification sheet, NEMA WD-6, UL 498 file E13399, verified 2026-09-23). The three conductors are:
- One hot (120V leg)
- One neutral
- One equipment ground
The math is straightforward. Watts equals volts times amps:
30A x 120V = 3,600 watts maximum capacity
This is the hard ceiling for a 30-amp coach on shore power. Every appliance and circuit in the RV must share that 3,600 watts simultaneously. (Code requirement: NEC 551.73(A) sets 3,600 volt-amperes as the calculation basis for a site equipped with both 20-ampere and 30-ampere supply facilities.)
A 30-amp service feeds a single breaker panel inside the coach. All circuits run on 120 volts from that single hot leg.
50-Amp Service: Two Legs, Two Hot Conductors
A 50-amp RV shore power connection uses the NEMA 14-50 configuration: three-pole, four-wire, rated at 50 amperes and 125/250 volts AC (manufacturer requirement: Leviton 279 14-50R specification, NEMA WD-6, UL 498, terminals marked X and Y hot, white neutral, green ground, verified 2026-09-23). The four conductors are:
- Hot leg 1 (120V)
- Hot leg 2 (120V, out of phase with leg 1)
- One neutral
- One equipment ground
The two legs are measured at 120V each relative to neutral, and at 240V relative to each other. Each leg independently supports up to 6,000 watts:
- Leg 1: 50A x 120V = 6,000 watts
- Leg 2: 50A x 120V = 6,000 watts
- Combined: 12,000 watts total
(Editorial calculation: our calculation from the manufacturer-published ratings. Inputs: 50A per leg x 120V per leg x 2 legs.)
Because each leg operates independently, a 50-amp coach can run a rooftop air conditioner on one leg at the same time it runs the microwave and electric water heater on the other leg, without either leg being overloaded.
The NEC requires 50-amp RV sites to be calculated at 12,000 volt-amperes per site for service and feeder sizing (code requirement: NEC 551.73(A), sites equipped with 50-ampere 208Y/120V or 120/240V supply facilities). Note what that figure is for: it sizes the PARK's service and feeders, and park operators may then apply the demand factors in Table 551.73(A). It is not a promise that your pedestal will deliver 12,000W continuously.
Why the Capacity Difference Is 3.3x, Not 1.7x
A common misconception is that 50-amp service is only slightly more capable than 30-amp service because 50 is only about 67 percent more than 30. That reasoning misses the two-leg architecture entirely.
The correct comparison:
- 30A service: 1 leg x 30A x 120V = 3,600W
- 50A service: 2 legs x 50A x 120V = 12,000W
12,000 divided by 3,600 is 3.33x. The jump in capacity comes primarily from doubling the number of hot legs, not from the 30-to-50 ampere increase within each leg.
If 50-amp service used a single 120V leg like 30-amp service, it would deliver only 6,000 watts: meaningfully more than 30-amp, but not 12,000. The two-leg split-phase design is what makes 50-amp service practical for running dual air conditioners simultaneously.
How to Identify Your RV's Shore Power Service
Check the plug on the end of your shore power cord:
- Three prongs, one T-slot: NEMA TT-30. Your RV is a 30-amp coach.
- Four prongs: NEMA 14-50, with two hot blades, a neutral, and a ground. Your RV is a 50-amp coach.
If you are uncertain, the main breaker inside the RV panel is definitive. A single 30-amp breaker confirms 30-amp service. A pair of breakers feeding two separate bus bars (typically two 50-amp breakers in a tandem configuration) confirms 50-amp service. (Common RV practice: breaker panel inspection is the accepted field method for confirming service type.)
What Each Service Realistically Powers
The table below shows representative wattages for common RV appliances. Use these as planning estimates; actual draw varies by brand, age, and operating conditions. Verify your own appliances with their nameplates before load-planning.
| Appliance | Typical Running Watts | Notes |
|---|---|---|
| 13,500 BTU rooftop A/C | 1,500 to 1,800W running | Starting surge can reach 2,800 to 3,600W |
| 15,000 BTU rooftop A/C | 1,800 to 2,000W running | Starting surge higher |
| Microwave (1,000W) | 1,000 to 1,800W | Runs briefly, high peak |
| Electric water heater | 1,200 to 1,500W | Often switchable to LP |
| Hair dryer | 1,500 to 1,875W | Most power-hungry common item |
| Converter/charger (typical) | 300 to 600W AC draw | While actively charging batteries |
| LED interior lighting | 20 to 80W total | Negligible load |
| Refrigerator (AC mode) | 150 to 500W | Cycles on and off |
On a 30-amp (3,600W) connection, running one large A/C unit, the microwave, and a hair dryer simultaneously would exceed the service limit. Staggering loads is the practical reality of 30-amp camping. On a 50-amp (12,000W) connection, both A/C units, the microwave, and the electric water heater can run at the same time with overhead to spare.
To calculate your specific load profile, use the RV load calculator. Enter each appliance and its wattage; the calculator returns your projected total and shows whether your service can support it.
Conductor and Wiring Requirements
The shore power cord conductor size must match the service rating. Requirements come from two sources: NEC Table 310.17 (free-air ampacity for single-insulated copper conductors, 2023 NEC) and manufacturer cord ratings.
30-amp shore power cord: Minimum 10 AWG copper conductors. Under NEC Table 310.17, 10 AWG copper at 60 degrees C is rated at 40A in free air, but NEC Section 240.4(D) limits overcurrent protection on 10 AWG to 30 amperes, matching the TT-30 breaker (code requirement: NEC 240.4(D) and Table 310.17, 2023 NEC, verified via Helukabel ampacity table document 2026-09-23).
50-amp shore power cord: Minimum 6 AWG copper conductors. Under NEC Table 310.17, 6 AWG copper at 60 degrees C is rated at 80A in free air, providing adequate margin for the 50A service (code requirement: NEC Table 310.17, 2023 NEC, verified via Helukabel ampacity table document 2026-09-23).
Using an undersized cord is a fire and overheating risk. Never substitute a lighter-gauge replacement cord without verifying it is rated for the service amperage.
Comparison Table: 30-Amp vs 50-Amp Shore Power
| Specification | 30-Amp Service | 50-Amp Service |
|---|---|---|
| NEMA plug configuration | TT-30 (3-prong) | 14-50 (4-prong) |
| Voltage | 120V, single leg | 120/240V, two legs |
| Maximum current | 30A | 50A per leg (100A total at 120V) |
| Maximum watt capacity | 3,600W | 12,000W |
| Hot conductors | 1 | 2 |
| Total conductors in cord | 3 (hot, neutral, ground) | 4 (hot, hot, neutral, ground) |
| Minimum cord wire gauge | 10 AWG copper | 6 AWG copper |
| NEC site load basis | 3,600 VA per site | 12,000 VA per site |
| Can run dual A/C? | No (single A/C only) | Yes |
| Typical coach type | Travel trailers, smaller Class A/C | Larger Class A, fifth wheels, high-load coaches |
Adapters: What a Dogbone Does and Does Not Do
A dogbone adapter (also called a pigtail adapter) converts between plug configurations. Two common scenarios:
50-amp coach at a 30-amp pedestal: A 50-amp-male-to-30-amp-female adapter lets you plug in, but your total available power drops to 3,600 watts. The 30-amp pedestal is the limit; the adapter does not create capacity. Both legs of the 50-amp coach are fed from the single 30-amp leg, so the coach must be operated as if it were a 30-amp connection. Running both A/C units is not possible. (Common RV practice: confirmed by multiple manufacturer adapter documentation; editorial recommendation: use a load management system if your 50-amp coach will regularly use 30-amp service.)
30-amp coach at a 50-amp pedestal: A 30-amp-female-to-50-amp-male adapter allows a 30-amp shore cord to plug into a 50-amp pedestal. The pedestal supplies only what the 30-amp cord and coach can accept: 3,600 watts. A 30-amp coach does not become a 50-amp coach by using a larger pedestal. The coach's 30-amp breaker and 10 AWG wiring are the limits. (Common RV practice: widely documented; code requirement: the receptacle and cord rating, not the pedestal rating alone, governs actual capacity per NEC Article 551.)
The key principle: an adapter changes the physical plug shape. It does not change the electrical capacity of either the coach or the pedestal supply. You are always limited by the lower-rated component in the connection.
For detailed guidance on using surge protection or an EMS when connecting at a mismatched pedestal, see 30-amp EMS at a 50-amp pedestal.
Do You Need Surge Protection at the Pedestal?
Both 30-amp and 50-amp service can be affected by pedestal problems: low voltage, open neutral, wiring errors, and voltage spikes. A basic surge protector absorbs voltage spikes. An electrical management system (EMS) disconnects power when the pedestal has unsafe conditions like low voltage, high voltage, or an open neutral. These are separate device categories with different levels of protection.
For the comparison between the two device types and which faults each one catches, see EMS vs surge protector.
NEC Campground Requirements
The NEC governs what campgrounds must provide. Under Article 551.71:
- Every site with electrical supply must have at least one 20-amp, 125V receptacle.
- A minimum of 70 percent of all sites with electrical supply must have a 30-amp, 125V receptacle (NEMA TT-30).
- A minimum of 20 percent of existing sites, and 40 percent of new sites, must have a 50-amp, 125/250V receptacle (NEMA 14-50).
- Every 50-amp site must also include a 30-amp receptacle.
- All of these receptacles must be weather-resistant. For the 50-amp 125/250V receptacle specifically, the weather-resistant requirement takes effect January 1, 2026.
(Code requirement: NEC 551.71(A)(B)(C), 2023 NEC.)
This is why most campground pedestals have both a 30-amp and a 50-amp outlet: code requires it on any 50-amp site. The 50-amp outlet being present at a site does not mean your 30-amp coach has access to more power. You are always limited to what your coach's inlet and internal wiring can handle.
Frequently Asked Questions
Can I upgrade my 30-amp RV to 50-amp?
Adding a 50-amp shore power inlet to a 30-amp RV is a significant electrical modification that requires rewiring the main panel and supply cord, upgrading internal wiring in affected circuits, and ensuring compliance with NEC Article 551. This is not a plug-swap; it involves the entire power distribution system. Consult a licensed RV electrician or your RV manufacturer before pursuing this path. (Editorial recommendation.)
Why do some 50-amp cords trip a 30-amp pedestal breaker?
When a 50-amp coach plugs into a 30-amp pedestal via a dogbone adapter, both of the coach's 120V legs are fed from the single 30-amp leg. If the coach draws more than 30 amps total across both legs, the 30-amp pedestal breaker trips. The solution is to shed load until total draw stays under 30 amps: turn off one A/C unit, avoid the microwave and hair dryer simultaneously, and use the RV load calculator to plan which appliances can run together. (Editorial recommendation.)
Does a 50-amp shore cord carry 240V to the RV?
The 50-amp shore cord carries two 120V legs and a neutral. Measured between the two hot legs, the voltage is 240V, which is why the NEMA 14-50 is rated at 125/250V. Inside most RVs, all appliances run at 120V, using one or the other leg. Some RVs use 240V for an electric range or dryer. If your coach has no 240V appliances, both legs still arrive at your panel; they are simply distributed across two bus bars feeding different 120V circuits. (Code requirement: NEC Article 551.42(D) requires a listed 50-ampere, 120/208-240V main power supply assembly for RVs with six or more circuits.)
Why is a 30-amp outlet called 30 amps but delivers 3,600W, while a 50-amp outlet delivers 12,000W instead of 6,000W?
The naming convention follows the ampere rating of the service, not the total watt capacity. A 30-amp outlet carries 30A on one 120V leg: 3,600W. A 50-amp outlet carries 50A on each of two 120V legs: 6,000W per leg, 12,000W total. The outlet should more logically be called a 100-amp outlet at 120V, since it carries 100 total amps at that voltage level, but the NEMA designation reflects the rating per leg, not the combined total. (Editorial recommendation: understanding the architecture prevents the common miscalculation of assuming only 6,000W is available on a 50-amp connection.)
What happens if I use an extension cord rated below my service amperage?
An undersized extension cord will carry more current than it is rated for, generating heat in the conductor insulation. This is a fire and shock hazard. If you must extend your shore power reach, use a cord rated for the full service amperage and with the same or heavier wire gauge than your standard shore power cord (10 AWG minimum for 30-amp service, 6 AWG for 50-amp service). Reduce the length as much as possible, since longer cords have higher resistance and generate more heat at a given current. (Safety recommendation. Code requirement: NEC Table 310.17 and Section 240.4(D) govern conductor and overcurrent protection sizing.)
Can I tell my service type from inside the RV without opening any panels?
Often, yes. Count the prongs on the shore power plug end of your cord: three prongs is a TT-30 and confirms 30-amp service. Four prongs is a 14-50 and confirms 50-amp service. If the cord is already plugged in, check the main breaker or the rating label on the power center inside the RV. (Common RV practice.)
Sources
- Leviton 7313 NEMA TT-30R Receptacle Specification Sheet Leviton manufacturer specification sheet for the 7313 TT-30R receptacle, the standard 30-amp RV pedestal device. Proves: 30 Amp, 125 Volt, NEMA TT-30R, 2 Pole, 3 Wire, grounding, for recreational vehicles; terminal identification Brass hot, White/Silver neutral, Green ground; terminals accept up to 4 AWG; 2 HP at rated voltage; standards NEMA WD-6, ANSI C-73, UL 498 file E13399, CSA C22.2 No. 42. Establishes that TT-30 is a single-hot 125V device, not a 240V connector. PDF verified live 2026-09-23. Authority tier: manufacturer specification sheet.
- Leviton 279 NEMA 14-50R Receptacle Technical Specification Leviton manufacturer product specification for the 279 series 14-50R receptacle, the standard 50-amp RV pedestal device. Proves: 50 A, 125/250 VAC, NEMA 14-50R, 3 Pole, 4 Wire, grounding; terminal identification X hot, Y hot, White neutral, Green ground, which is the two-hot-leg architecture this article explains; terminals accept #4 AWG; 3 HP at rated voltage; standards NEMA WD-6, ANSI C73, UL 498 and UL 486E, CSA 22.2 No 42 file E13399. Read in a live browser session 2026-09-23. Authority tier: manufacturer specification.
- NEC Table 310.17 Allowable Ampacity Tables (2023 NEC via Helukabel Technical Documents) NFPA 70 NEC 2023 Table 310.17: Ampacities of Single-Insulated Conductors in Free Air (Copper). Confirms: 10 AWG copper at 60C = 40A in free air; NEC Section 240.4(D) limits overcurrent protection for 10 AWG to 30A. 6 AWG copper at 60C = 80A in free air. Used to source the wire gauge requirements for 30-amp (10 AWG) and 50-amp (6 AWG) shore power cords. Authority tier: NEC code standard (NFPA 70, 2023 edition). Verified live 2026-09-23 via PDF fetch.
- NEC Article 551.71 Receptacle Requirements at RV Parks (2023 NEC via Leviton Captain Code reference) Leviton Captain Code 2023 portal reproducing the verbatim NEC 551.71(A)(B)(C)(F) text with the 2023 revision summary. Proves: every RV site with electrical supply needs at least one 20-ampere 125V weather-resistant receptacle; a minimum of 70 percent of sites need a 30-ampere 125V weather-resistant receptacle; a minimum of 20 percent of existing and 40 percent of all new sites need a 50-ampere 125/250V weather-resistant receptacle; every 50-ampere site must also carry a 30-ampere 125V receptacle; and the weather-resistant requirement for 50-ampere receptacles becomes effective January 1, 2026. Read in a live browser session 2026-09-23. Authority tier: verbatim code text republished by a manufacturer.
- NEC 551.73 Calculated Load, basis of calculations and Table 551.73(A) demand factors Reproduction of NFPA 70 NEC Article 551.73. Proves the calculation basis this article cites: not less than 12,000 volt-amperes per site equipped with 50-ampere 208Y/120V or 120/240V supply facilities, 3,600 volt-amperes per site equipped with both 20-ampere and 30-ampere supply facilities, 2,400 volt-amperes for 20-ampere only, and 600 volt-amperes for 20-ampere tent sites. Also carries Table 551.73(A) demand factors (100 percent for 1 site down to 41 percent for 36 or more), which is why a park's service is not simply the sum of its site ratings. Replaces an earlier citation to a wiki page that now returns 404. Verified live 2026-09-23. Authority tier: code reference.
Published 2026-09-23. Electrical specifications are model-specific: confirm every figure against the manual for your exact equipment before acting on it.