When you plan a backup power setup, the transfer switch is the component that decides whether your generator or backup source can safely deliver power. You're usually weighing two different form factors: a transfer switch that can switch itself, or a generator-ready inlet box that puts you in control. The 100A Dual Power Automatic Transfer Switch and the 20 Amp Generator Transfer Switch with Weatherproof Power Inlet Box represent these two approaches. Let's see which one matches your panel, your generator, and how much hands-on switching you want.
Quick Verdict
The 100A Dual Power Automatic Transfer Switch is the better pick if you want hands-off failover and have a DIN-rail panel where the switch can live. The 20 Amp Generator Transfer Switch with Weatherproof Power Inlet Box is the better pick if you want a weather-resistant, prewired generator hookup for a single circuit and don't mind handling the switch yourself.
Comparison at a Glance
| Feature | 100A Automatic Transfer Switch | 20A Generator Transfer Switch Inlet Box |
|---|---|---|
| Price | USD 38.88 | USD 89.09 |
| Price Bar | ||
| Transfer Type | Automatic and Manual | Manual |
| Capacity | 2P 100 Amp | 20 Amp, 125V |
| Mounting | DIN Rail Mount | Predrilled inlet box, indoor/outdoor |
| Notable Specs | ABS, red copper, tinned iron | NEMA 5-20P, ETL listed, green power indicator |
Where the 100A Switch Wins
The 100A automatic transfer switch is built for speed and capacity. It operates in both automatic and manual modes, so it can move the load to a backup circuit on its own when the main feed drops. The design shifts in as little as 50 milliseconds, which helps keep lights on without you having to run to the panel. The ABS, red copper, and tinned iron construction is made to survive repeated switching. If your goal is backup power for a large load, this switch is the right direction.
Where the 20A Inlet Box Wins
The 20A generator transfer switch is a complete, self-contained generator connection. It includes a power inlet box, a prewired internal cord, and precut knockouts for easier mounting. A light on the lid confirms when the generator is plugged in and supplying power, which is handy in low light. You stay in control of when the generator feed is connected. For a hookup that doesn't require a large panel change, this inlet box is the simpler option.
Product Notes
100A Dual Power Automatic Transfer Switch
This switch gives you self-operated transfer in a DIN-rail-mounted format. The contact arrangement is normally open/close with a common connection, which is the standard setup for moving between a primary and backup source. The DIN rail mounting and ABS, red copper, and tinned iron construction point to a durable, panel-level component. Choose it when you want the transfer to happen on its own and you have the enclosure infrastructure to support it. The trade-off is that this is not a weatherproof inlet box, so you'll need to arrange the generator hookup separately. That makes the overall install less turnkey, but the hands-free switching is the payoff.
20 Amp Generator Transfer Switch with Weatherproof Inlet Box
This transfer switch is designed to be a more complete generator hookup. It arrives with a NEMA 5-20P weatherproof power inlet box, a built-in circuit breaker, prewired internal wiring, and precut knockouts, which makes the installation more straightforward than building a generator inlet from separate parts. The green power indicator on the lid gives you a clear visual signal that the generator cord is connected, and it carries an ETL listing for use in US and Canadian electrical systems. The limitation is that you'll be the one switching the load, and the unit is built around a smaller, dedicated load rather than a large panel.
Final Choice by Use Case
If you want backup power without standing at the switch, choose the 100A Dual Power Automatic Transfer Switch. If you need a generator connection for one dedicated circuit, choose the 20 Amp Generator Transfer Switch with Weatherproof Inlet Box.
