When you're shopping for transfer switches for automatic backup, the first big decision is scale. Do you need a compact 20-amp weatherproof inlet box to feed a portable generator, or a 200-amp heavy-duty double-throw switch for much larger loads? These two options sit at opposite ends of the power spectrum, and choosing wrong means either buying more capacity than you need or trying to power everything through a small 20-amp connection.
Quick verdict
If your backup power comes from a portable generator, the 20A Generator Transfer Switch is the better match. If you need to switch a much larger load, the 200A Manual Generator Transfer Switch is the better fit.
At a glance
| Feature | 20A Inlet Box | 200A Double-Throw Switch |
|---|---|---|
| Price | $89.09 | $203.55 |
| Electrical rating | 20A, 125V | 200A, 48,000W |
| Operation | Plugs into NEMA 5-20P generator | Lever shifts between main and auxiliary power |
| Standout feature | Green power indicator | Aluminum connections |
| Placement | Indoor or outdoor | Wall mount |
Where each product wins
- The 20A Inlet Box wins for compact portable-generator hookups.
- The 200A Double-Throw Switch wins for high-capacity manual switching.
Product notes
20 Amp Generator Transfer Switch - 125V Weatherproof Power Inlet Box with NEMA 5
For small backup jobs, this transfer switch keeps things simple. The weatherproof NEMA 5-20P inlet box comes prewired and with predrilled knockouts, so the hookup is more straightforward than starting from scratch. A green indicator light on the lid shows when the generator cord is plugged in, which is a handy cue in low-light conditions. The unit is ETL listed and intended for 20-amp, 3-prong NEMA 5-20P generators used in the USA and Canada, and it can be placed indoors or outdoors. The limitation is its scale: a 20A/125V rating means it won't handle a whole-house load or large 240V appliances. At $89.09, it's the lower-priced choice when your needs are modest.
200A Manual Generator Transfer Switch - Heavy Duty 48000W Double-Throw
For high-capacity switching, this wall-mounted double-throw switch brings 200A and 48,000W of headroom. A simple control lever shifts between the main power source and an auxiliary source such as a gas generator or solar setup, and the aluminum connections avoid electronic components for long-term reliability. It's a different approach from a small inlet box: instead of plugging a cord into a weatherproof receptacle, you're operating a large transfer switch rated for serious loads. The trade-off is cost and scale. At $203.55, it's the more expensive of the two, and if your generator is only 20A, you'll be paying for capacity you won't use. It's designed for wall-mount installation and comes as a single unit.
Final choice by use case
Pick the 20A Generator Transfer Switch for portable generator backup.
Pick the 200A Manual Generator Transfer Switch for a large-capacity installation.
