Fuses & Fuse Testers

About Fuses & Fuse Testers

Fuses and fuse testers are essential electrical safety components and diagnostic tools for automotive, industrial, and electrical applications. A fuse acts as a critical safety device that protects electrical circuits from damage caused by excess current, melting and breaking the circuit when current flow exceeds safe levels. Whether you're working on vehicle electrics, wiring electrical equipment, or maintaining automotive systems, having the right fuses and reliable testing equipment is fundamental to safe and effective work. Modern vehicles contain numerous electrical circuits controlling everything from entertainment systems to engine management, making proper fuse specification and testing capability crucial for tradespeople and DIY enthusiasts alike.

The comprehensive range available at Tooled-Up.com includes automotive blade fuses in mini, micro, standard, and maxi sizes, fuse assortments for workshop use, splashproof fuse holders, and specialist testing equipment including fuse checkers and pullers. These products cater to professional auto electricians, mobile mechanics, fleet maintenance teams, and home mechanics who need reliable circuit protection and diagnostic capabilities. With various amperage ratings available—from low-amp circuits to heavy-duty applications—you'll find the right fuse specification for any automotive or electrical project. Quality fuses and testing equipment prevent costly electrical damage and potential fire hazards whilst ensuring compliance with UK electrical safety standards.

Tooled-Up stocks an extensive selection of fuse-related products from Sealey, a trusted name in automotive electrical components. The range includes convenient fuse assortments with multiple amperage ratings in organised storage cases, anti-theft battery terminals with integrated fuse holders, specialist fuse pullers that make replacement quick and safe without damaging surrounding components, and splashproof holders for harsh environments. Whether you're maintaining a commercial vehicle fleet, working on agricultural machinery, or simply keeping your personal vehicle roadworthy, having proper circuit protection and testing capability is essential for reliable electrical system performance.

Jargon Buster

• Blade Fuse: A type of automotive fuse with two flat metal prongs that plug into a fuse holder. Available in mini, micro, standard (ATO/ATC), and maxi sizes depending on the amperage and application requirements. The colour-coded plastic body allows visual identification of amperage ratings.
• Amperage Rating: The maximum current (measured in amps) a fuse can safely handle before it melts and breaks the circuit. Common automotive ratings range from 2A to 80A, with each circuit requiring specific protection levels matched to the wiring gauge and connected components.
• Fuse Holder: The socket or housing that securely holds a fuse within an electrical circuit. Can be panel-mounted, inline, or part of a vehicle's fuse box. Splashproof versions offer additional environmental protection against moisture, dirt, and contaminants in harsh conditions.
• Circuit Protection: The process of safeguarding electrical circuits from damage caused by overload, short circuits, or component failure. Fuses provide this protection by creating an intentional weak point that fails safely before more expensive components or wiring are damaged.
• Accessory Circuit: Additional electrical circuits added to a vehicle or equipment for powering extra devices like dashcams, phone chargers, auxiliary lighting, or refrigeration units. These require proper fuse protection matched to the load to prevent damage to the vehicle's main electrical system.
• Fuse Tester: A diagnostic tool used to check whether a fuse has blown without removing it from the circuit. Often includes LED indicators for quick visual confirmation and may incorporate a fuse puller for easy removal. Professional models work across 12-24V systems covering cars, vans, and commercial vehicles.

Who Uses Fuses & Fuse Testers?

• Auto Electricians: Professionals specialising in vehicle electrical systems who regularly diagnose faults and replace blown fuses across various vehicle types, from passenger cars to commercial vehicles.
• Mobile Mechanics: Tradespeople who need portable fuse assortments and testing equipment for on-site vehicle repairs and diagnostics at customer locations or roadside breakdowns.
• Fleet Maintenance Teams: Workshop staff maintaining commercial vehicle fleets who require bulk fuse supplies and reliable testing equipment to keep vehicles operational and minimise downtime.
• Breakdown Recovery Technicians: Roadside assistance professionals who diagnose and resolve electrical faults, often starting with fuse checks as the first diagnostic step.
• Agricultural Engineers: Specialists working on farm machinery and equipment with complex electrical systems requiring appropriate circuit protection in harsh, contaminated environments.
• Marine Electricians: Professionals working on boat electrical systems where splashproof fuse holders are essential for reliability in damp, corrosive saltwater conditions.
• Caravan and Motorhome Technicians: Specialists maintaining leisure vehicle electrical systems with multiple accessory circuits for lighting, heating, refrigeration, and entertainment systems.
• Plant and Equipment Operators: Construction and industrial workers maintaining electrical systems on diggers, generators, and site equipment that operate in demanding conditions.
• DIY Enthusiasts and Car Owners: Home mechanics who perform their own vehicle maintenance and need basic fuse supplies and testing capability for routine electrical troubleshooting.

How to Choose the Right Fuses & Fuse Testers

Identify the Correct Fuse Type: Modern vehicles use blade-style fuses in four main sizes—micro (smallest), mini, standard (ATO/ATC), and maxi (largest for high-current applications). Check your vehicle handbook or existing fuses to determine which type your vehicle uses. Some older vehicles or specialist equipment may use glass cartridge or ceramic fuses instead. The physical size is important as each requires matching fuse holders and covers different amperage ranges.

Match the Amperage Rating Precisely: Never replace a fuse with a higher amperage rating than specified, as this removes essential circuit protection and creates fire risk. Common automotive ratings include 2A, 3A, 4A, 5A, 7.5A, 10A, 15A, 20A, 25A, and 30A for standard circuits, with higher ratings up to 80A for starter motors and charging systems. The correct rating is usually marked on the fuse box cover or in your vehicle documentation. Fuses are colour-coded for easy identification—for example, blue typically indicates 15A whilst yellow indicates 20A.

Consider a Comprehensive Fuse Assortment: For workshop use or regular maintenance, a fuse assortment offers excellent value and convenience. Assortments typically contain multiple fuses across common amperage ratings in organised storage cases, ensuring you have the right replacement immediately available. This is particularly valuable for mobile mechanics, fleet maintenance operations, and busy workshops. Look for assortments with at least 100 pieces covering the most commonly used ratings.

Select Appropriate Fuse Holders for the Environment: When adding accessory circuits or replacing damaged holders, consider the operating environment and current requirements. Splashproof holders provide essential protection in wet conditions, engine bay installations, or outdoor equipment where moisture ingress could cause corrosion and failure. Standard holders suit protected interior locations like dashboard installations. Ensure the holder matches your fuse type (mini, micro, standard, or maxi) and can handle the circuit's maximum current rating.

Invest in Quality Testing Equipment: A quality fuse tester with integrated puller saves time during diagnostics and prevents damage to fuses and holders. Look for testers that work with 12-24V systems (covering cars, vans, and commercial vehicles) and feature clear LED indicators for quick fault identification without needing to remove the fuse. Combination tools that incorporate both testing and pulling functions offer the best value for professional use, whilst simple continuity testers suit occasional DIY applications.

Plan for Security and Specialised Applications: In commercial vehicles or high-theft areas, anti-theft battery terminals with integrated fuse holders provide an additional layer of security whilst maintaining proper circuit protection. These specialist products are particularly valuable for construction site vehicles and agricultural equipment. For marine applications or harsh industrial environments, prioritise splashproof or fully sealed fuse holders that meet IP (Ingress Protection) ratings suitable for the conditions.

Popular Accessories

• Multimeters and Electrical Testers: Essential diagnostic tools for measuring voltage, current, and continuity when troubleshooting electrical faults beyond simple fuse testing.
• Wire Strippers and Crimping Tools: Necessary for professional installation of new fuse holders and accessory circuits, ensuring secure connections and proper electrical contact.
• Electrical Tape and Heat Shrink Tubing: Insulation materials for protecting connections and preventing short circuits in automotive wiring installations.
• Automotive Wiring Kits and Cable: Automotive-grade cable in various gauges for adding new circuits that require fuse protection, colour-coded for easy identification.
• Battery Chargers and Jump Starters: Power equipment that works alongside proper fuse protection for vehicle electrical maintenance and emergency starting.
• Circuit Testers and Test Lights: Simple diagnostic tools for checking whether circuits are live before fuse replacement, helping identify the source of electrical faults.
• Tool Storage Cases and Organisers: Organised storage solutions for keeping fuse assortments, holders, and testing equipment together and protected during transport.
• Cable Ties and Fixings: Essential for securing new wiring runs and keeping automotive electrical installations neat and protected from abrasion.

Safety Information

Always Disconnect the Battery Before Working: Before replacing fuses or installing new fuse holders, disconnect the negative battery terminal to eliminate risk of short circuits, sparks, or electrical shock. This is particularly important when working with high-current circuits or in the engine bay where accidental earthing can occur. Wait several minutes after disconnection to allow capacitors in modern vehicle systems to discharge fully.

Never Use Incorrect Fuse Ratings: Installing a higher-rated fuse than specified bypasses essential circuit protection and can cause electrical fires, component damage, or wiring meltdown. If a fuse blows repeatedly, there's an underlying fault that requires proper diagnosis—not a higher-rated fuse. Makeshift solutions like wrapping blown fuses in foil or wire are extremely dangerous and can result in vehicle fires. Consult vehicle documentation or a qualified auto electrician if uncertain about correct ratings.

Identify and Rectify Underlying Faults: A blown fuse is a symptom, not the problem itself. Before replacing a fuse, identify and rectify the cause—whether it's a short circuit, faulty component, chafed wiring, or overloaded circuit. Simply replacing fuses without diagnosis can lead to repeated failures and potential hazards. Use proper diagnostic equipment to trace faults and inspect wiring for damage before restoring power.

Use Proper Tools for Fuse Removal: Always use a dedicated fuse puller or appropriate tool to remove fuses from holders. Makeshift tools like screwdrivers, pliers, or metal implements can damage fuse holders, bend fuse terminals, or cause short circuits that damage sensitive electronic components. Purpose-designed pullers ensure safe removal without risk to you or the electrical system, and many fuse testers include integrated pullers for convenience.

Consider Environmental Protection Requirements: In wet or contaminated environments, use splashproof fuse holders to prevent moisture ingress that could cause corrosion, poor contact, or short circuits. This is particularly important for marine applications, agricultural machinery, construction equipment, and under-bonnet installations exposed to the elements. Ensure fuse holder seals are intact and properly fitted to maintain IP ratings and prevent environmental damage.

Frequently Asked Questions

How can I tell if a fuse has blown?
Most blade-style automotive fuses are translucent, allowing you to see the internal wire element through the plastic body. A blown fuse will have a visibly broken or melted wire inside, often with blackening or discolouration. For certainty, use a fuse tester which will indicate instantly whether the fuse is functional using LED indicators, or test with a multimeter set to continuity mode. Some fuses may appear intact visually but have failed, so testing is always more reliable than visual inspection alone.

What's the difference between mini, micro, and standard blade fuses?
These terms refer to the physical size of automotive blade fuses. Standard (also called ATO or ATC) fuses are the largest and most common in older vehicles and high-current applications. Mini fuses (ATM) are approximately half the size and widely used in modern cars where space is limited. Micro fuses are the smallest variant for space-constrained applications in newer vehicles. Each type requires matching fuse holders and covers different amperage ranges, though there's overlap. You cannot interchange them as they won't fit properly or make secure contact.

Can I replace a 10A fuse with a 15A fuse if I keep blowing fuses?
No, never increase fuse ratings as a solution to repeated failures. The fuse rating is carefully calculated by vehicle manufacturers to protect the wiring gauge and components in that specific circuit. Using a higher-rated fuse removes this protection and risks electrical fires or expensive component damage. If a correctly-rated fuse blows repeatedly, there's an underlying fault—such as a short circuit, chafed wiring, failing component, or overloaded circuit—that requires proper diagnosis and repair before restoring power.

How do I know which amperage fuse my circuit needs?
The required fuse rating is typically marked on the fuse box cover, printed on the fuse box itself, or listed in your vehicle handbook. When adding new accessory circuits, calculate the maximum current draw of your device using the formula: watts ÷ volts = amps. For example, a 60-watt accessory on a 12V system draws 5 amps, so you'd use a 7.5A or 10A fuse (the next standard rating above). Always round up to the next available rating and use cable of appropriate gauge to handle the current safely.

Why do I need splashproof fuse holders instead of standard ones?
Splashproof (also called weatherproof or waterproof) fuse holders feature sealed construction that prevents moisture, dirt, salt, and contaminants from entering the fuse connection. This is essential for any fuse installed in exposed locations such as engine bays, under vehicles, on agricultural machinery, marine applications, or outdoor equipment. Moisture ingress causes corrosion of the fuse terminals, intermittent connections, voltage drops, and eventual failure of standard fuse holders in these environments. The small additional cost provides significantly improved reliability in harsh conditions.