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)
Device type: Low-voltage surge protective device (SPD), series / inline installation
Circuit pair protected: Two pair (Terminal A/B & Terminal C/D)
- 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 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:
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 SP24A24AA is installed in line with the circuit being protected.
Bidirectional: either side can be used as IN/OUT.
- Maintain continuity: connect A→A, B→B, C→C and D→D 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 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.
Product Details
| 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 |
Installation
Professional installation is recommended. Installation should be performed by a qualified, licensed electrical professional in accordance with the product instructions, applicable electrical codes, and local requirements.
Always turn off power to the circuit and connected equipment before installation. Verify that power has been disabled using an appropriate voltage sensing device before working on the circuit.
24VAC Four-Wire Installation Notes
- The SP24A24AA is designed for compatible 24VAC low-voltage circuits only.
- This model is designed to protect two 24VAC electrical circuits, or two pairs of conductors.
- Verify the correct voltage application before installation.
- The SP24A24AA must be installed inline, or in series, with the wiring of the equipment being protected.
- Choose a mounting location that allows easy access and straightforward wiring, then mount the surge protector securely.
- The unit is bidirectional, so either side may be used as the input or output side.
- Maintain continuity through the surge protector by connecting A to A, B to B, C to C, and D to D.
- Keep the same polarity or circuit path through each matching terminal pair.
- Maintain at least 18 inches of wire between the surge protector and the protected equipment for best performance.
- For best results, connect the attached green 14 AWG ground wire to a solid equipment grounding point when possible.
Typical Applications
- Two 24VAC control or signaling circuits
- HVAC control circuits
- Thermostat and equipment control wiring
- Air handler, furnace, or equipment control boards
- Low-voltage control and monitoring circuits
- Security, access control, CCTV, or similar low-voltage wiring applications
Final Check
Before restoring power, inspect all terminations for tightness and correct wiring. Verify that matching terminals are connected properly: A to A, B to B, C to C, and D to D. Confirm that the green ground wire is connected when possible and make sure all conductors are properly seated.
After installation is complete and confirmed safe, restore power and verify normal equipment operation.
Service and Warranty Note
This product contains no serviceable parts. Do not open or tamper with the device. Tampering with the product or performing a Hi-Po test may damage the surge protector and void the warranty.
Refer to the SP24A24AA installation instructions for complete wiring, spacing, grounding, troubleshooting, and product-specific installation requirements.
Warranty
Bad Wolf surge protection devices include a 5-year product warranty.
Eligible products may also include connected equipment warranty coverage when properly installed and registered according to the warranty terms.
Please review the full warranty terms for complete details, limitations, registration requirements, and coverage information.
FAQ
What is the SP24A24AA mainly used for?
The SP24A24AA is used to help protect two-pair, four-wire 24VAC low-voltage circuits from damaging overvoltage and surge events. It can be used on compatible low-voltage power, control, data, and signaling circuits.
What voltage is the SP24A24AA designed for?
The SP24A24AA is designed for 24VAC circuits only. It should not be used on DC circuits or AC circuits above 24 volts.
What does the 2.5KA rating mean?
The 2.5KA rating refers to the surge current capacity of the device. The SP24A24AA is designed to help protect compatible 24VAC circuits from damaging surge and overvoltage events when properly installed.
What type of circuits can the SP24A24AA protect?
The SP24A24AA can be used to protect two 24VAC pairs, one four-wire 24VAC circuit, or two separate two-wire 24VAC circuits, as long as the application matches the product ratings and installation requirements.
Can this be used for HVAC controls or thermostat wiring?
Yes. The SP24A24AA can be used on compatible 24VAC HVAC control wiring, thermostat circuits, communication links, and control board circuits where two-pair or four-wire surge protection is needed.
Can the SP24A24AA be used for fire alarm circuits?
Yes. The SP24A24AA may be used on compatible 24VAC fire alarm signaling, notification, or control circuits where the circuit voltage and wiring match the product specifications. Always verify compatibility with the fire alarm system requirements before installation.
Can this be used for security, access control, or gate operator circuits?
Yes. The SP24A24AA may be used on compatible 24VAC security, alarm, access control, gate operator, and low-voltage control circuits that match the product ratings.
Can the SP24A24AA be used for telecommunications or data applications?
Yes, when the circuit is a compatible 24VAC low-voltage data or signaling circuit. The SP24A24AA should not be used on circuits that do not match its voltage rating or application requirements.
Can this be used on 4–20 mA control loops?
The SP24A24AA may be used on compatible 24VAC control or signaling applications where the circuit matches the product ratings. Always verify the voltage, signal type, and system requirements before installation.
Is the SP24A24AA for power circuits, data circuits, or both?
The SP24A24AA can be used for compatible 24VAC low-voltage power, data, control, and signaling circuits. It is intended for overvoltage and surge protection only and must be used within its rated application.
How is the SP24A24AA wired?
The SP24A24AA uses screw terminals for the protected circuit connections. The circuit wiring should be connected according to the product instructions and the specific circuit being protected.
Does the SP24A24AA connect to ground?
The SP24A24AA includes an optional ground wire pigtail. The ground connection may be used when appropriate for the installation and system design.
Where should the SP24A24AA be installed?
The SP24A24AA is commonly installed near the control board, control panel, equipment being protected, building entry point, outdoor equipment connection, or another location where surge protection is needed on a compatible 24VAC circuit.
Does the SP24A24AA have status lights?
No. The SP24A24AA does not have status indicator lights.
Can the SP24A24AA be installed outdoors?
The SP24A24AA is intended for indoor installation only. If used near outdoor equipment, it should be installed in a suitable protected indoor or enclosed location according to the product instructions and applicable requirements.
Does the SP24A24AA provide short circuit or overcurrent protection?
No. The SP24A24AA provides overvoltage and surge protection only. It does not provide short circuit or overcurrent protection. The protected circuit should have appropriate circuit protection as required for the system.
Can the SP24A24AA be used on DC circuits?
No. The SP24A24AA is designed for 24VAC circuits only and should not be used on DC applications.
Can the SP24A24AA be used on 120VAC or higher-voltage AC circuits?
No. The SP24A24AA should not be used on 120VAC circuits or any AC circuit above 24 volts. Using the device outside its rating can create an unsafe condition and damage the product or connected equipment.
Who should install this product?
This product should be installed by a qualified technician, electrician, low-voltage installer, HVAC contractor, fire alarm technician, security technician, or other qualified person familiar with the circuit and equipment being protected.
Does this product include a warranty?
Bad Wolf surge protection devices include a 5-year product warranty. Eligible products may also include connected equipment warranty coverage when properly installed and registered according to the warranty terms.
Specifications
SP24A24AA Specifications
| Model Number | SP24A24AA |
|---|---|
| Product Type | 24VAC four-wire low-voltage surge protector |
| Device Type | Low-voltage SPD, series / inline installation |
| Application | Two 24VAC control, signaling, or low-voltage equipment circuits |
| Circuits Protected | Two 24VAC circuits through terminals A/B and C/D |
| Nominal Operating Voltage | 24VAC (x2) |
| MCOV | 33V (x2) |
| Clamping Voltage | 39V (x2) |
| Maximum Continuous Current | 5A (x2) |
| Surge Current Rating | 2.5kA (x2) |
| Protection Modes | Differential mode, line-to-line, and common mode, line-to-ground |
| Terminal Wire Range | 30–14 AWG |
| Operating & Storage Temperature | -31°F to +158°F (-35°C to +70°C) |
| Recommended Spacing to Protected Equipment | Minimum 18 inches |
| Ground Connection | Attached green 14 AWG ground wire; connect to equipment ground when possible |
| Installation Direction | Bidirectional; either side may be used as IN or OUT |
| Serviceability | No serviceable parts |
Wiring Notes
- The SP24A24AA is designed to protect two 24VAC circuits, or two pairs of conductors.
- Install the surge protector inline, or in series, with the wiring of the equipment being protected.
- Maintain continuity through the device by connecting A to A, B to B, C to C, and D to D.
- The unit is bidirectional, so either side may be used as the input or output side.
- For best results, connect the attached green 14 AWG ground wire to equipment ground when possible.
- Maintain at least 18 inches of wire between the surge protector and the protected equipment.
- Do not perform a Hi-Po test on this surge protector. Hi-Po testing may damage the device and void the warranty.
Specifications are subject to change. Refer to the product label and installation instructions for complete product-specific ratings and installation requirements.