Automatically switches between two 120VAC power sources - shore power and generator. Built-in 20-30 second delay for generator stabilization.
The PowerMax PMTS-30A Automatic Transfer Switch provides seamless, hands-free power management for RVs, travel trailers, and smaller off-grid systems. This relay-based transfer switch automatically monitors two separate 120VAC power sources and intelligently switches between them to ensure continuous power to your appliances and systems.
Designed specifically for 30-amp RV electrical systems, the PMTS-30A eliminates the need for manual switching between shore power and generator. When shore power or grid power is available, the transfer switch connects it directly to your RV's distribution panel. When you start your onboard generator, the switch waits 20-30 seconds for voltage to stabilize, then automatically transfers electrical power to your appliances. When the generator stops or shore power returns, the switch immediately transfers back - no manual intervention required.
Intelligent relay system automatically selects available power source - eliminates manual shore/generator switching
Built-in 20-30 second delay allows generator voltage to stabilize before powering appliances
Handles full 30 amp 120VAC service - perfect for travel trailers and smaller RVs
Certified for safety and electromagnetic compatibility - meets all regulatory requirements
Shore Power Priority: When plugged into shore power (campground hookup, grid power, or primary source), the PMTS-30A automatically connects that power to your RV's AC distribution panel. All your appliances receive stable shore power without any action required from you. Generator Startup: When you start your onboard generator (or switch to a secondary power source like an inverter), the transfer switch detects the voltage. It waits 20-30 seconds for the generator to stabilize and reach proper voltage/frequency before switching. Automatic Transfer: After the delay period, the relay-based switch smoothly transfers from shore power to generator power. Your appliances continue operating without interruption during the transition. Return to Shore Power: When the generator stops or shore power returns, the switch immediately transfers back to the primary power source. No delay is needed since shore power is already stable. Optional Bypass: The PMTS-30A includes a timer bypass switch that allows you to manually override the 20-30 second delay if needed for testing or emergency situations.
Travel Trailers & RVs: Automatically switch between campground shore power and onboard generator. Perfect for 30-amp RV service - no more manual switching or unplugging shore power before starting generator. Small RVs & Campers: Ideal for Class C motorhomes, small Class A motorhomes, and travel trailers with single air conditioner units and 30-amp electrical systems. Off-Grid Cabins: Seamlessly transfer between grid power (when available) and backup generator. Ensures continuous power during utility outages. Solar Systems with Generator Backup: Primary power from solar inverter (120VAC output), automatic transfer to generator when batteries are low or demand exceeds solar production. Backup Power Systems: Automatically engage generator power during utility outages. Switch back to grid power when restored without manual intervention. Small Business Backup: Keep critical single-phase 120V equipment running during power failures - computers, POS systems, refrigeration.
• Professional Installation Recommended: Transfer switches should be installed by a qualified, licensed electrician. Improper installation can cause electric shock, fire, or death. • Multiple Live Circuits: This device has TWO AC power inputs. BOTH inputs must be completely disconnected before any work is performed. • Location Restrictions: DO NOT install in compartments containing batteries or flammable materials (gasoline, propane). Unit produces arcs and sparks during switching. • Heat & Water Protection: DO NOT install near heat sources (water heaters, furnaces) or under refrigerators. NOT designed for wet locations - must be protected from water contact. • Ventilation Required: DO NOT mount in zero-clearance compartments. Overheating may result. Ensure adequate airflow. • Wire Specifications: All field wires must be rated for at least 105°C. Use appropriate gauge for 30-amp service (10 AWG minimum). • Never Drill Housing: DO NOT drill through metal housing. Use existing knockouts only - metal shavings can damage relay operation.
In The Box: • PMTS-30A Automatic Transfer Switch • Internal 12V DC Relay (Pre-installed) • Integrated Ground Terminal Bar • 3 Knockout Plugs (2 x 7/8", 1 x 1") • Installation Manual with Wiring Diagrams • Warranty Documentation NOT Included (Required for Installation): • AC Wiring (10 AWG minimum for 30A service) • Wire Connectors/Lugs • Mounting Hardware • Electrical Box or Enclosure (if needed) • Professional Electrician Installation Service
Compare the PMTS-30A with the 50-amp model to determine which transfer switch is right for your electrical system.
The PMTS-30A accepts two separate 120VAC power sources (Input 1 and Input 2) and provides a single 120VAC output. Common configurations include:
Important: Input 1 (shore power) always has priority. When Input 1 is present, the switch connects it to the output. When Input 1 fails or is disconnected, the switch waits 20-30 seconds for Input 2 (generator) to stabilize, then transfers power. When Input 1 returns, the switch immediately transfers back.
Location Selection: • Install as close as possible to shore power cord entrance and generator to minimize voltage drop • Choose dry, cool location away from heat sources (water heaters, furnaces, refrigerators) • Ensure adequate ventilation - do not install in zero-clearance compartments • Keep away from battery compartments and flammable material storage • Can be mounted in any position for flexible placement in tight RV spaces Wire Sizing & Connections: • Use minimum 10 AWG copper wire for all 30-amp connections (8 AWG recommended for long runs) • All field wiring must be rated for at least 105°C temperature • Terminals accept 6-14 AWG wire with ring terminals • Torque terminal connections to 13 inch-pounds • Torque ground bar connections to 35 inch-pounds • Use proper crimped ring terminals - do not use push-on connectors Grounding: • All grounds are connected internally within the transfer switch • Connect all equipment grounds to the integrated ground bar • Ensure proper grounding of both input power sources • Ground bar suitable for 6-14 AWG conductors Safety Compliance: • Rated for circuits capable of delivering up to 3000 RMS symmetrical amps • Maximum operating voltage: 240VAC • Install appropriate overcurrent protection (30A circuit breakers) on all inputs • Follow all local electrical codes and NEC requirements Testing: • With shore power connected, verify output voltage matches input • Start generator and verify 20-30 second transfer delay • Turn off generator and verify immediate return to shore power • Test timer bypass switch function if equipped • Verify all connections are tight and properly torqued
Product Documentation: Download PMTS-30A & PMTS-50A Installation Manual (PDF) Download PMTS Series Specification Sheet (PDF) Warranty Information: 2-Year Limited Manufacturer's Warranty Covers defects in materials and workmanship under normal use No forms required - call tech support for rapid replacement Replacement unit shipped within 24 hours of defect confirmation Return shipping label provided for defective unit Company Website: www.powermaxconverters.com PowerMax Converters 5107 Lena Road, Suite 108 Bradenton, FL 34211
A: The easiest way to determine your RV's electrical service is to look at your shore power cord plug. A 30-amp plug has three prongs arranged in a distinctive configuration with one blade rotated 90 degrees - it looks like an upside-down "Y". A 50-amp plug has four prongs (two hot, one neutral, one ground) in a different configuration. Additionally, check your RV's shore power inlet on the exterior - it will be labeled with either "30A" or "50A". Inside your RV, look at the main circuit breaker panel - a 30-amp system will have a single 30-amp main breaker, while a 50-amp system will have two 50-amp breakers. Generally, smaller travel trailers and Class C motorhomes use 30-amp service with one air conditioner, while larger motorhomes and fifth wheels use 50-amp service with dual air conditioners and more appliances. If you're still unsure, check your RV owner's manual or the data plate inside the RV (usually near the entrance door) which lists electrical specifications.
A: Yes, the PMTS-30A works excellently with portable inverter generators. In fact, the built-in 20-30 second transfer delay is particularly beneficial for inverter generators because even though they produce clean power, they still need time to reach stable voltage and frequency when first started. The transfer switch ensures your appliances only receive power after the generator has stabilized. However, make sure your inverter generator is rated for at least 30 amps continuous output (approximately 3600 watts) to handle your RV's full electrical load. Most 3000-4000 watt inverter generators can handle 30-amp RV service. Popular models like the Honda EU3000i, Champion 3400, or Westinghouse iGen4500 work perfectly with the PMTS-30A. The automatic transfer feature means you can start your generator without unplugging shore power - the switch handles everything automatically. When you turn off the generator, the switch instantly returns to shore power, and you can shut down the generator knowing your RV is still powered.
A: No, you do not need to turn off appliances before transfer - that's one of the main benefits of an automatic transfer switch. The PMTS-30A is designed to switch power while appliances are running without causing damage. However, there are a few best practices: (1) The 20-30 second delay when switching TO generator power ensures voltage is stable before appliances receive power, (2) When switching back to shore power, the transfer is instantaneous because shore power is already stable, (3) Most appliances handle the brief transition without issue - TVs might flicker, microwaves might restart, but no damage occurs. That said, some users prefer to turn off high-draw appliances (air conditioner, microwave) before switching as a precaution, especially if switching to a small generator that might struggle with high starting currents. The transfer switch protects against unstable voltage, but it's still smart RV practice to avoid starting multiple high-draw appliances simultaneously on generator power. Overall, you can leave most things running and let the automatic switch do its job.
A: Yes, upgrading from a manual shore/generator selector switch to the PMTS-30A is a popular RV modification that significantly improves convenience. Many RVs come with manual switches that require you to: physically turn a dial or flip a switch between "shore" and "generator" positions, remember to switch positions before starting the generator (or risk backfeeding), and manually switch back to shore power when done. The automatic transfer switch eliminates all of this. The upgrade process requires a licensed electrician to: (1) Remove the old manual switch, (2) Install the PMTS-30A in an appropriate location (often near the distribution panel), (3) Rewire the shore power inlet and generator output to the transfer switch inputs, (4) Connect the transfer switch output to your RV's main distribution panel, (5) Install proper grounding and overcurrent protection. The installation typically takes 2-4 hours for an experienced RV electrician. Cost ranges from $400-800 including the transfer switch ($89-159) plus labor ($300-600). This is one of the best quality-of-life upgrades for RVs with generators - you'll wonder how you ever lived without it.
A: With the PMTS-30A automatic transfer switch, you can safely plug into shore power while your generator is running - the switch handles this scenario perfectly. Here's what happens: The transfer switch always prioritizes Input 1 (shore power) over Input 2 (generator). When you plug into shore power while the generator is running, the PMTS-30A immediately detects the presence of shore power and transfers from generator to shore power. Your RV's appliances continue operating without interruption - you might notice lights flicker briefly during the transfer, but that's normal. Once on shore power, you can safely turn off your generator. The automatic switch prevents any possibility of "backfeeding" where generator power could flow back into the shore power system (which is dangerous and could damage both the generator and campground electrical system). This is a huge safety and convenience feature compared to manual switches, where you must remember to manually switch to shore power BEFORE plugging in, or risk damage. With the PMTS-30A, you can plug in anytime without worry - the switch always does the right thing.
A: Yes, the PMTS-30A is fully compatible with lithium battery systems and solar inverters. The transfer switch simply monitors and switches between two 120VAC power sources - it doesn't care where that AC power comes from (shore power, generator, solar inverter, or battery inverter). Many modern RV owners are upgrading to lithium batteries with solar panels and inverters for off-grid camping. You can configure the PMTS-30A in several ways: (1) Solar Inverter as Primary: Connect your solar inverter's AC output (120VAC from batteries) to Input 1, and generator to Input 2. Uses solar power normally, switches to generator (with delay) when batteries are depleted. (2) Shore Power Primary: Connect shore power to Input 1, solar inverter to Input 2. Uses shore power at campgrounds, automatically switches to solar inverter power when boondocking. The 20-30 second delay when switching to Input 2 means there will be a brief power interruption if your batteries die while running on solar - this is a limitation to be aware of. For critical loads, consider using an inverter with a built-in transfer switch for instant transfer. But for most RV applications, the PMTS-30A works great with modern solar and lithium systems.