Best Small Automatic Transfer Switches for Reliable Power Backup
When selecting a small automatic transfer switch (ATS), the goal is uninterrupted power for essential devices and quiet, dependable switching. This guide highlights five compact, 120V, 15A-20A ATS options suited for homes, offices, or RV setups. The top picks are best for users needing quick switchover, easy installation, and compatibility with generators or inverters. Each product is evaluated for who it’s best for, and a practical limitation is noted to aid decision-making.
| Product | Brand | Best For | |
|---|---|---|---|
| AC120V 15Amp Automatic Transfer Switch | YAURILO | Home computers and consumer electronics | Fast enough for typical devices; indoor/outdoor use |
| AC120V 15Amp Automatic Transfer Switch | HCDC | Smart devices and office setups | Smallest transfer time among options; robust relay design |
| OONO AC120V 15Amp Automatic Transfer Switch | OONO | Residential or light commercial loads | Compact and straightforward; fast switching |
| EIIDAR ATS AC120V 20 Amp | EIIDAR | Higher-load scenarios | Higher current capability; IP65 rating for outdoor use |
| KUTTOLE 15 Amp Transfer Switch | KUTTOLE | Budget-conscious setups needing reliable relays | Solid performance; simple two-input switching |
YAURILO 15A Automatic Transfer Switch
Features: Converts between two AC sources, switching from utility to inverter/generator as needed. Built with a durable plastic shell and corrosion-resistant metal components. Suitable for indoor or outdoor use, with moisture resistance for varied environments.
Best for: Small home setups requiring seamless handoff between utility power and a backup generator or inverter. The unit’s compact design and outdoor-capable materials make it a good choice for basic off-grid readiness.
Limitations: May be best suited for lighter loads; ensure your connected devices do not exceed 15A to avoid overloading.
HCDC 15A Automatic Transfer Switch
Features: Inline transfer relay with four high-power SPST relays to switch between AC INPUT 2 (utility) and AC INPUT 1 (inverter/generator). Operating voltage 90–135V, 50/60Hz. Transfer time under 30 milliseconds. Ground wires are connected internally for reliability.
Best for: Users needing a quick, robust transfer with a design that minimizes arcing and preserves sensitive electronics during switchover.
Limitations: Slightly longer physical footprint may require more mounting space; verify enclosure compatibility in tight installations.
OONO 15A Automatic Transfer Switch
Features: 0.015 second transfer time with 90–135V input range. Designed for quick switchover between utility/shore power and inverter/generator sources. Includes compatibility with standard cables and straightforward installation.
Best for: Environments where even a brief interruption matters less; ideal for basic residential setups that require reliable, fast switching.
Limitations: 0.015 second switchover is excellent, but confirm the load does not exceed 15A to maintain reliability.
KUTTOLE 15A Transfer Switch
Features: Combines mechanical and electrical transfer with four high-power SPST relays to avoid arc issues. Operating voltage 90–135V, 50/60Hz, 15A max current. Transfer time under 30ms; two-input to output switching is designed for reliable operation.
Best for: Users seeking reliable, cost-effective switching for RVs or small homes with generators or inverters, using robust relay design to reduce arcing.
Limitations: Slightly longer installation steps due to dual-input wiring; verify wiring diagram and enclosure fit before mounting.
Buying Guide: Key Considerations For Small ATS Purchases
What load will you run? Estimate total amperage and peak loads. Choose an ATS that comfortably handles your expected draw (e.g., 15–20A for most residential setups).
Where will you install? Consider enclosure size, mounting type (DIN rail vs. inline), and whether you need outdoor or indoor protection (IP rating, moisture resistance).
Switching speed and reliability: Transfer times range from under 15 ms to under 30 ms. Faster switching reduces risk to sensitive equipment but verify compatibility with your devices.
Number of inputs: Most small ATS units switch between two sources (utility vs. inverter/generator). Confirm the two-source design aligns with your backup plan.
Installation and wiring: Look for clear wiring diagrams and simple inline mounting. Ensure your electrical system can accommodate the ATS and complies with local codes.
Durability and materials: Plastic housings can be moisture resistant for outdoor use, while metal components improve longevity in demanding environments.
Frequently Asked Questions
- What is an automatic transfer switch used for? It automatically switches the load to a backup power source when the primary source fails, helping prevent downtime for critical devices.
- How fast does an ATS switch? Transfer times commonly range from 0.015 to 0.030 seconds, depending on the model and load.
- Can I install an ATS myself? Basic inline units can be installed by a competent DIYer with electrical experience; however, professional installation is advised for safety and code compliance.
- What load should I plan for? Determine the sum of devices you expect to run during an outage and choose an ATS with an amperage rating that exceeds that sum by a comfortable margin.
- Is IP65 protection important for an ATS? IP65 protection is beneficial for outdoor installations, offering moisture and dust resistance in harsher environments.
- Do all ATS units support both generator and inverter inputs? Most small ATS units support switching between utility/shore power and an alternative source like an inverter or generator, but verify the specific inputs for your model.