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50 Amp RV Shore Power Calculator

Estimate running current on each leg of a North American 50 A RV shore connection. L1 and L2 are its two power legs, each rated for 50 A. Select the leg that powers each 120 V device. A 240 V device connected across both legs adds the same running current to each. The calculator compares L1 and L2 separately.

Not sure what to enter? Read the step-by-step guide.

Your inputs

AC load 1

Use the RV distribution panel or documentation to identify L1 or L2 for each 120 V device. Choose both legs only for a device connected across them at 240 V. Enter running AC input amps, or real AC input watts with the operating voltage and power factor. Do not use VA as watts.

Check the RV distribution panel or documentation to identify each 120 V load's leg. Include every AC load running from shore at the same time, including a charger's AC input. Do not guess the leg or enter its DC output current. Inputs stay in this browser.

50A shore power comparison

How each leg compares

Running current compared separately with the 50 A rating on each leg.

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Leg 1 · L1

Leg 2 · L2

Current by device

    Enter your AC devices and select the connection that powers each one.

    This compares running current with the two 50 A leg ratings only. It does not predict breaker trips or check motor startup, long-duration load rules, voltage drop, neutral current, branch circuits, adapters, wiring, or pedestal condition. A 30 A adapter does not provide two independent 50 A supplies.

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    See calculation details, assumptions and sources

    A NEMA 14-50 shore connection is rated 50 A at 125/250 V and has two hot legs. For each 120 V load, choose its actual leg, L1 or L2. A 240 V load connected across L1 and L2 draws the same line current from both legs. For each device, enter running RMS AC amps or calculate amps = real W ÷ (RMS V × power factor). Use the load's actual operating voltage: line-to-neutral for a 120 V load, line-to-line for a 240 V load.

    L1 A = sum of L1 loads + sum of 240 V loads; L2 A = sum of L2 loads + sum of 240 V loads. Multiply each device's current by its quantity before adding. Each leg's headroom is 50 A − that leg's A. Both leg totals must be at or below 50 A to be within the connector's running-current ratings. No total-amps shortcut can show an overloaded leg.

    Example: a 120 V device draws 20 A on L1 and another draws 35 A on L2. A 2,400 W device connected across both legs at 240 V with PF 1 adds 10 A to each leg. L1 is 30 A and L2 is 45 A. If the L2 load rises to 45 A, L2 becomes 55 A even though L1 stays at 30 A. These are examples, not appliance presets.

    The result needs the real leg assignment. It does not infer that assignment from a device's watts, outlet location or label. It assumes a normal 125/250 V split-phase shore supply, without power assist or adapters, and applies no blanket 80% factor or startup multiplier. Check the RV and pedestal ratings and the rules that apply to the duration and installation separately. For a TT-30 supply, use the 30 A calculator.

    References: Hubbell NEMA 14-50R specification lists 50 A, 125/250 V, single-phase and four-wire ratings; Progressive Dynamics 50 A RV transfer switch manual lists 120/240 V and 50 A line ratings; Victron Energy Meter manual explains real power and power factor. See the site methodology.