SP24A24AA — 24VAC Two-Pair Low-Voltage Surge Protector (Series / Inline) with Equipment Ground Connection
$99.00
SP24A24AA is a 24VAC double circuit (two-pair) surge protector for inline (series) installation on low-voltage control wiring. Protects one circuit through Terminal A and Terminal B and a seperate circuit through Terminal C and Terminal D and uses a green equipment ground lead—ideal for HVAC controls, thermostats, doorbells, and fire/security loops.
24 VAC circuits only — verify voltage before installation.
Specifications (SP24A24AA)
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Device type: Low-voltage surge protective device (SPD), series / inline installation
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Circuit pair protected: Two pair (Terminal A/B & Terminal C/D)
- Nominal operating voltage: 24 VAC
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MCOV (Maximum Continuous Operating Voltage): 33 V
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Clamping voltage: 39 V
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Maximum continuous current: 5 A
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Surge current rating: 2.5 kA
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Protection modes: Differential (line-to-line) and Common mode (line-to-ground)
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Terminal wire range: 30–14 AWG
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Operating temperature: −35°C to +70°C (−31°F to +158°F)
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Recommended spacing to protected equipment: ≥ 18 inches
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Ground: Green lead provided; connect to equipment ground
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Serviceability: Sealed / non-serviceable; no user-serviceable parts (do not Hi-Pot test)
The Bad Wolf SP24A24AA is a 24VAC two-pair low-voltage surge protector designed for inline (series) installation on control and signaling circuits. It protects one 24VAC circuit through Terminal A/B and Terminal C/D and uses the green equipment ground lead to help manage common-mode surges. SP24A24AA helps protect sensitive low-voltage equipment from transient overvoltage events caused by nearby lightning, utility switching, and inductive load switching.
Where it’s used
SP24A24AA is commonly installed on 24VAC control power and low-voltage signaling circuits, including:
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HVAC control circuits and thermostats
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Air handler/furnace control boards
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Doorbell and smart doorbell transformers
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Security/CCTV power or control loops
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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)
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Series (inline) install required: the SP24A24AA is installed in line with the circuit being protected.
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Bidirectional: either side can be used as IN/OUT.
- Maintain continuity: connect A→A, B→B, C→C and D→D through the SPD.
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Ground connection: Connect the green ground lead to a proper equipment ground for best performance.
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Maintain at least 18 inches between the SPD and the equipment being protected.
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Verify the circuit is 24 VAC before installation and install per applicable electrical codes by a qualified professional.
Status and service
The SP24A24AA 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 |