SP24AA — 24VAC Single-Pair Low-Voltage Surge Protector (Series / Inline) with Equipment Ground Connection
$79.00
SP24AA is a 24VAC single-pair low-voltage control circuits (HVAC, thermostats, doorbells, and fire/secuiry/alarm loops). surge protector for inline (series) installation on control and signaling circuits. Protects one circuit through Terminal A and Terminal B and uses a green equipment ground lead.
24 VAC circuits only — verify voltage before installation.
Specifications (SP24AA)
Device type: Low-voltage surge protective device (SPD), series / inline installation
Circuit pair protected: Single pair (Terminal A & Terminal B)
- Nominal operating voltage: 24 VAC
MCOV (Maximum Continuous Operating Voltage): 33 V
Clamping voltage: 39 V
Maximum continuous current: 5 A
Surge current rating: 2.5 kA
Protection modes: Differential (line-to-line) and Common mode (line-to-ground)
Terminal wire range: 30–14 AWG
Operating temperature: −35°C to +70°C (−31°F to +158°F)
Recommended spacing to protected equipment: ≥ 18 inches
Ground: Green lead provided; connect to equipment ground
Serviceability: Sealed / non-serviceable; no user-serviceable parts (do not Hi-Pot test)
The Bad Wolf SP24AA is a 24VAC single-pair low-voltage surge protector designed for inline (series) installation on control and signaling circuits. It protects one 24VAC circuit through Terminal A and Terminal B and uses the green equipment ground lead to help manage common-mode surges. SP24AA helps protect sensitive low-voltage equipment from transient overvoltage events caused by nearby lightning, utility switching, and inductive load switching.
Where it’s used
SP24AA is commonly installed on 24VAC control power and low-voltage signaling circuits, including:
HVAC control circuits and thermostats
Air handler/furnace control boards
Doorbell and smart doorbell transformers
Security/CCTV power or control loops
Fire/security low-voltage loops and other control wiring
- Helps protect control boards, transformers, relays, and connected low-voltage devices from transient surges.
Installation notes (important)
Series (inline) install required: the SP24AA is installed in line with the circuit being protected.
Bidirectional: either side can be used as IN/OUT.
- Maintain continuity: connect A→A and B→B through the SPD.
Ground connection: Connect the green ground lead to a proper equipment ground for best performance.
Maintain at least 18 inches between the SPD and the equipment being protected.
Verify the circuit is 24 VAC before installation and install per applicable electrical codes by a qualified professional.
Status and service
The SP24AA is sealed and non-serviceable. There are no user-serviceable parts. Do not Hi-Pot test the device, as this may damage the SPD.
Additional information
| Weight | 5 oz |
|---|---|
| Dimensions | 5.125 × 3.25 × 1.25 in |
| Continuous Current Rating | 5 |
| Environmental Rating | Indoor |
| Type of Electrical Current | AC |
| Voltage (Vac) | 24 |
| Application | Doorbell, HVAC, Thermostat |