Choosing an automatic transfer switch for your backup power setup means weighing the electrical configuration you need against the space you have to install it. Both of these 100-amp units switch between the main supply and a secondary power source automatically, but they are built for different installation styles and conductor counts. The Dual Power Automatic Transfer Switch, 2P 100 Amp, is a two-pole unit with a DIN rail mount, while the Automatic Transfer Switch 3P 100A is a three-pole unit with a wall-mount body. Your decision will come down to whether you need single-phase or three-phase backup switching, and whether your enclosure has a DIN rail or a flat wall surface.
Quick Verdict
If your backup circuit is single-phase and you want a switch that clips onto a DIN rail, the Dual Power 2P 100A is the lower-priced option. If you need three-pole switching for three-phase equipment and prefer a wall-mounted transfer switch, the Automatic Transfer Switch 3P 100A gives you that coverage, though it costs more.
At a Glance
| Feature | Dual Power 2P 100A | Automatic Transfer Switch 3P 100A |
|---|---|---|
| Price | USD 38.88 | USD 53.81 |
| Poles | 2 | 3 |
| Mounting | DIN Rail Mount | Wall-mounted |
| Material | ABS, Red Copper, Tinned Iron | Cold-rolled Sheet |
| Transfer Time | ≤50ms | <0.1s |
| Operation Mode | Automatic and Manual | Automatic/Manual Switching |
Where the Dual Power 2P 100A Wins
- Price: It is the lower-priced of the two.
- Mounting: The DIN rail mount integrates directly into standard panel layouts.
- Response speed: The specified transfer time is ≤50ms, quicker than the other unit's under-0.1s.
Where the Automatic Transfer Switch 3P 100A Wins
- Pole count: Three poles allow it to switch three-phase power, which a 2P switch cannot.
- Mounting: The wall-mount design works in standalone enclosures without a DIN rail.
- Voltage ratings: It carries a 690V AC insulation voltage and 8KV impact withstand voltage, making it suitable for higher-voltage systems.
Product Notes
#### Dual Power Automatic Transfer Switch, 2P 100 Amp Automatic Transfer Switch
With a listed price of $38.88, this transfer switch is the lower-priced of the pair. It mounts on a DIN rail, which makes it a natural fit for existing panel boxes, and it supports both automatic and manual switching for testing or maintenance. Its construction uses ABS, red copper, and tinned iron, and the switch responds quickly when the main power drops. The clear limitation is the 2P design: it only interrupts two conductors, so it cannot handle three-phase backup loads. If you don't have a DIN rail in your enclosure, you also need to plan around the mounting style.
#### Automatic Transfer Switch 3P 100A Transfer Switch Dual-Power Transfer Switch
At $53.81, the 3P transfer switch is the higher-priced option, but it brings three-pole switching for three-phase circuits. The wall-mounted body is made from cold-rolled sheet with a plastic-sprayed finish, giving it rust resistance for long-term installation. It operates automatically and manually, and its conversion time is fast enough for most backup needs. The trade-off is the cost premium over the 2P model, and the mounting requirement is a wall surface rather than a DIN rail. Also, the response is not instantaneous, though the listed figure keeps interruptions brief.
Final Choice by Use Case
Choose the Dual Power 2P 100A if you have a single-phase backup circuit and a DIN rail available. It delivers automatic and manual switching, a fast response, and the lower price. Choose the Automatic Transfer Switch 3P 100A if you need three-pole operation for three-phase equipment and can mount the unit on a wall. It costs more but adds the pole count and voltage ratings that a three-phase setup requires. For most single-phase panels, the two-pole model is the more straightforward fit; for three-phase installations, the 3P switch is the one to pick.
