HVAC surge protector
Intermatic AG3000
A compact SPD that mounts on the outdoor AC disconnect, protecting the most expensive motor load in the house at its own connection point.
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Best for
Adding a protection layer at the AC condenser or heat pump
Specifications
| SPD Type | Type 1 or 2 (UL 1449 4th Ed.) |
|---|---|
| Surge capacity | 50 kA |
| Nominal discharge (In) | 20 kA |
| VPR | 700 V L-N / 1200 V L-L |
| SCCR | 200 kA |
| Enclosure | Type 4X outdoor, UV resistant |
| Indicators | Single green LED |
| Warranty | 3 years, $7,500 connected equipment |
Specifications as published by Intermatic. Confirm against the current spec sheet before buying — manufacturers revise models without renaming them.
What's good
- Protects the compressor and its board right at the disconnect, downstream of everything else
- TPMOV design fails open rather than on fire — its own selling point in a plastic box on a wall
- Trivial add-on during any AC or heat pump service call
What's not
- Not a whole-house device — it's a layer for one circuit
- Shortest warranty of the group
Our verdict
A heat pump or AC inverter board is a four-figure part hanging off an outdoor disconnect. This is the cheap, code-listed way to give it its own clamp — in addition to, not instead of, the panel SPD.
Compare with the alternatives
- Siemens BoltShield FSPD140 — the default whole-house pick on any brand of panel
- Eaton CHSPT2ULTRA — a lifetime-warranty alternative at the top of the market
- Square D HEPD80 — the proven value pick, especially on square d panels
- Leviton P2120-B — service-entrance installs and meter-adjacent mounting
- Tripp Lite by Eaton ISOBAR6ULTRA — the point-of-use layer at your electronics