1. Introduction
This manual provides essential information for the safe and effective installation, operation, and maintenance of your Littelfuse 32V Waterproof ATO and MINI In-Line Fuse Holders. These fuse holders are designed to provide reliable circuit protection in demanding environments, including automotive and marine applications, thanks to their IP67-rated dustproof and waterproof enclosure.
Please read this manual thoroughly before installation and keep it for future reference.
2. Safety Information
Always observe the following safety precautions to prevent personal injury or damage to the product and connected equipment:
- Disconnect power from the circuit before installing or servicing the fuse holder.
- Ensure the fuse holder and fuse rating match the circuit's voltage and current requirements.
- Do not exceed the maximum voltage and current ratings specified for the fuse holder.
- Use only the specified fuse types (ATO or MINI blade fuses) with the corresponding holder.
- Ensure all connections are secure and properly insulated to prevent short circuits.
- Avoid installing the fuse holder in locations exposed to extreme temperatures or corrosive substances beyond its rated capabilities.
- If you are unsure about any aspect of installation, consult a qualified electrician or automotive technician.
3. Product Components
Each Littelfuse In-Line Fuse Holder typically consists of the following parts:
- Fuse Holder Body: The main housing for the fuse.
- Wire Leads: Pre-attached wires for in-line installation, available in various gauges (e.g., 12AWG, 14AWG, 16AWG) and colors.
- Protective Cover/Cap: An integrated, hinged or removable cap that seals the fuse compartment, providing IP67-rated dustproof and waterproof protection.
- Internal Contacts: Tin-plated copper alloy contacts designed for corrosion resistance and secure fuse connection.
4. Specifications
4.1. ATO FHAC Series In-Line Fuse Holders
| Feature | Specification |
|---|---|
| Max Current Rating | 20A, 25A, 30A |
| Max Current Rating Terminal | 20A |
| Fuse Type | ATO® Fuse |
| Flammability Rating | UL 94 V-0 |
| Ingress Protection | IP67 |
| Input Terminals | ATO® Fuse Blades |
| Mounting Method | In-Line Fuse Holder |
| Max Voltage Rating | 32 VDC |
| Wire Size Options | 12 AWG, 14 AWG, 16 AWG, 0.5 MM2 |
4.2. MINI FHM Series In-Line Fuse Holders
| Feature | Specification |
|---|---|
| Max Current Rating | 30A and 20A |
| Fuse Type | MINI® Fuse |
| Flammability Rating | UL 94 V-2 / V-0 |
| Ingress Protection | IP67 |
| Input Terminals | MINI® Fuse Blades |
| Mounting Method | In-Line Fuse Holder |
| Max Voltage Rating | 58 VDC |
| Wire Description | 125°C rated, GXL Red wires, Tinned stranded copper; 125°C rated PE-X FLR2X-B Yellow wires |
5. Installation
The Littelfuse In-Line Fuse Holders are designed for easy installation into existing circuits. Follow these general steps:
- Disconnect Power: Ensure the power source to the circuit where the fuse holder will be installed is completely disconnected.
- Select Location: Choose a suitable location for the fuse holder. Its compact design allows it to be mounted virtually anywhere along the circuit.
- Cut Wire: Carefully cut the circuit wire at the desired installation point.
- Strip Wire Ends: Strip a small amount of insulation from the ends of the circuit wire and the fuse holder's wire leads to expose the copper conductors.
- Connect Wires: Connect the fuse holder's wire leads to the circuit wires. This can be done using appropriate crimp connectors, soldering, or other secure electrical connection methods. Ensure a strong, low-resistance connection.
- Insulate Connections: Properly insulate all connections using heat shrink tubing or electrical tape to prevent short circuits and protect against environmental factors.
- Insert Fuse: Open the protective cap of the fuse holder. Insert the correct type and rating (ATO or MINI, e.g., 20A, 30A) blade fuse into the holder. Ensure it is seated firmly.
- Close Cap: Securely close the protective cap over the fuse. The built-in cover seals the fuse to offer IP67-rated dustproof and waterproof protection.
- Restore Power: Once all connections are secure and insulated, and the fuse is properly installed, restore power to the circuit.
For detailed 2D prints and specific installation guides, refer to the Littelfuse website (littelfuse.com/FHM for MINI FHM Series, and littelfuse.com/FHAC for ATO FHAC Series).
6. Operation
Once installed, the fuse holder operates passively, providing continuous circuit protection. The primary operational aspect involves fuse replacement:
- Identify Blown Fuse: If a circuit protected by the fuse holder stops functioning, the fuse may have blown.
- Disconnect Power: Always disconnect power to the circuit before attempting to replace a fuse.
- Open Cap: Open the protective cap of the fuse holder.
- Remove Blown Fuse: Carefully remove the blown fuse from the holder.
- Insert New Fuse: Insert a new fuse of the exact same type and rating (e.g., ATO 20A, MINI 30A) into the holder. Never use a fuse with a higher rating than specified for the circuit.
- Close Cap: Securely close the protective cap.
- Restore Power: Restore power to the circuit and verify functionality.
7. Maintenance
Littelfuse In-Line Fuse Holders are designed for minimal maintenance. However, periodic checks can ensure continued reliability:
- Visual Inspection: Periodically inspect the fuse holder and its connections for any signs of damage, corrosion, or wear. Ensure the protective cap is securely closed.
- Cleanliness: Keep the exterior of the fuse holder clean from dirt, debris, and moisture.
- Connection Integrity: Occasionally check that all wire connections are tight and secure.
- Fuse Check: If a circuit is intermittent, check the fuse for proper seating and integrity, even if it hasn't visibly blown.
8. Troubleshooting
Most issues related to fuse holders involve the fuse itself or the connections.
| Problem | Possible Cause | Solution |
|---|---|---|
| Circuit not receiving power | Blown fuse | Replace fuse with one of the correct type and rating. Investigate cause of fuse blowing (e.g., short circuit, overload). |
| Intermittent power to circuit | Loose fuse or poor wire connection | Ensure fuse is seated firmly. Check and secure all wire connections. |
| Fuse blows immediately after replacement | Overload or short circuit in the protected circuit | Do NOT install a higher rated fuse. Disconnect all loads and test the circuit for shorts or excessive current draw. Consult a professional if necessary. |
| Water ingress inside fuse holder | Protective cap not properly closed or damaged | Ensure cap is fully sealed. If damaged, replace the fuse holder to maintain IP67 rating. |
9. User Tips
- Correct Fuse Selection: Always use a fuse that matches the amperage rating of the circuit it protects. Using an undersized fuse will lead to frequent blowing, while an oversized fuse can fail to protect the circuit, potentially causing damage or fire.
- Wire Gauge Matching: Ensure the wire gauge of the fuse holder (e.g., 12AWG, 14AWG, 16AWG) is appropriate for the current it will carry and matches or exceeds the gauge of the circuit wire it's being installed into.
- Accessibility: While these holders can be mounted virtually anywhere, consider accessibility for future fuse replacement when choosing an installation spot.
10. Frequently Asked Questions (FAQ)
- Q: What is the difference between an ATO and a MINI fuse holder?
- A: ATO and MINI refer to the physical size and shape of the blade fuses they accommodate. ATO fuses are larger and more common in older automotive applications, while MINI fuses are smaller and used in many modern vehicles due to space constraints. Ensure you use the correct fuse type for your specific holder.
- Q: Can I use this fuse holder in a marine environment?
- A: Yes, both the ATO FHAC Series and MINI FHM Series are designed with an IP67 rating, making them dustproof and waterproof, suitable for marine and other harsh environments.
- Q: Are fuses included with the holder?
- A: Fuses are typically sold separately unless explicitly stated otherwise. Please check the product packaging or description for details.
11. Warranty and Support
For warranty information, technical support, and additional resources, please visit the official Littelfuse website. You can find detailed product documentation, including 2D prints and installation guides, on their product pages:
- For ATO FHAC Series: Refer to littelfuse.com/FHAC
- For MINI FHM Series: Refer to littelfuse.com/FHM
Littelfuse is committed to providing high-quality products and support. If you encounter any issues not covered in this manual, please contact Littelfuse customer service directly.
