A 30-amp RV receptacle supplies 120V, not 240V. A shore-power mistake can energize exposed metal, start a fire or damage every connected appliance, so this page explains design decisions rather than presenting a DIY terminal-by-terminal recipe.
Use a qualified RV electrician
120V work in a mobile metal-bodied vehicle combines shock, fire, vibration and moisture hazards. Use listed RV-suitable equipment, follow current applicable requirements and have the completed system inspected and tested before connection.
The complete shore-power path
A typical system can include:
- campground pedestal and correctly rated detachable cord;
- weather-resistant vehicle inlet;
- main disconnecting and overcurrent protection;
- energy-management or transfer equipment where fitted;
- AC distribution panel and branch-circuit protection;
- converter/charger or inverter-charger;
- receptacle and appliance circuits with required GFCI protection;
- continuous equipment-grounding path and vehicle bonding as specified.
The order and functions depend on the listed products. "Inlet to charger" is not a complete design when the vehicle also has outlets, an inverter, a generator or multiple AC sources.
30A supply versus household adapters
A TT-30 connection is a 30A, 120V RV supply. When the van uses an adapter from a 15A or 20A household receptacle, the available power remains limited by the upstream circuit and adapter. The vehicle's main rating does not create more capacity.
Approximate maximum apparent power is:
| Supply | Calculation | Theoretical maximum |
|---|---|---|
| 15A at 120V | 120 x 15 | 1,800VA |
| 20A at 120V | 120 x 20 | 2,400VA |
| 30A at 120V | 120 x 30 | 3,600VA |
Continuous-load and equipment requirements can reduce usable capacity. Battery charging, water heating, air conditioning and cooking loads must be coordinated rather than assumed to run together.
Inlet, cord and conductor selection
Match the cord and inlet configuration to the intended supply. Verify voltage and configuration markings instead of identifying a connector only by appearance.
For the fixed wiring, check:
- copper conductor ampacity and insulation temperature rating;
- mobile/RV suitability and resistance to vibration;
- wet-location or exterior exposure;
- bend radius and strain relief;
- protection from sharp metal edges and heat;
- terminal compatibility with conductor class and size;
- support spacing required by the selected wiring method.
Solid residential building wire should not be substituted merely because its gauge is familiar. Use the wiring method required for the vehicle and equipment.
Main protection belongs in the design
The inlet-to-panel conductors need protection coordinated with their rating, and branch circuits need their own correctly rated protective devices. A charger having internal electronics protection does not automatically protect all fixed wiring between the inlet and the device.
Keep the main disconnect accessible and clearly labelled. Protect cable at penetrations and place enclosures where condensation, plumbing leaks or stored objects cannot compromise them.
Neutral, equipment ground and multiple sources
Hot and neutral carry normal load current. The equipment-grounding conductor is a protective fault path and should not carry normal current.
When shore power is active, the source neutral-ground relationship normally comes from the supply. If an inverter or generator can also feed the panel, the transfer and neutral arrangement must ensure the correct relationship for the active source without creating an unintended parallel path.
Do not add a neutral-ground jumper in the vehicle panel from a generic diagram. The inverter or inverter-charger manual must be read together with the transfer-equipment and panel instructions.
GFCI and supply-quality protection
Provide GFCI protection where required and test it using the manufacturer's procedure. An RV electrical management system can also detect some pedestal faults and abnormal voltage, but it is not a substitute for correct internal wiring, overcurrent protection or grounding.
Commissioning checklist
Before energizing the system, a competent person should verify:
- equipment ratings, listings and enclosure suitability;
- conductor identification, routing, support and strain relief;
- terminal torque using the manufacturer's values;
- protective-conductor continuity;
- insulation and absence of unintended neutral-ground continuity where applicable;
- polarity and source voltage;
- main and branch protective-device ratings;
- GFCI operation;
- transfer behavior in every permitted source mode;
- charger current and thermal behavior under load.
Do not perform live measurements unless trained and equipped for them. A non-contact voltage detector alone cannot prove correct polarity, grounding or safe transfer behavior.
Related
Frequently Asked Questions
Keep the build moving
Make the next build decision easier.
Get practical diagrams, calculator updates and honest product comparisons in your inbox.
Roam Wired
Roam Wired turns campervan research into practical plans. We publish transparent guidance, a free electrical design tool and marketplace resources for UK and US van builders.
About our approach