Frequently Asked Questions

General Questions

What is Wire Solved?

Wire Solved is a wire sizing calculator for 12V and 24V DC electrical systems. It calculates the correct wire gauge based on both amperage AND voltage drop over distance, plus recommends proper fuse sizing for your circuit.

Why not just use a wire chart?

Standard wire charts only consider ampacity (how much current a wire can safely carry without overheating). They don’t account for voltage drop over distance.

This means a chart might recommend 16 AWG for a 10A load, but if you’re running 30 feet of wire, you’ll lose 15% of your voltage and your device won’t work properly. Wire Solved prevents this by calculating both.

Is Wire Solved free to use?

Yes, completely free. No account required, no paywalls, no ads. We don’t collect or sell your data.

Do I need an internet connection?

You need an internet connection to initially load the calculator and learning pages. Once loaded, calculations happen entirely in your browser and work offline.

For fully offline use, we’re planning a Progressive Web App (PWA) that can be installed on your phone.

Can I save my calculations?

Yes! The System Builder feature (second tab) lets you create multi-circuit wiring systems, save them to your browser’s localStorage, and export them as PDF or JSON files.

Your saved systems stay on your device - we never see them.

Technical Questions

How accurate are the calculations?

Wire Solved uses standard electrical engineering formulas and data from the National Electrical Code (NEC):

• Wire resistance: NEC Table 8 (ohms per 1000 feet for copper conductors)
• Ampacity ratings: NEC Table 310.15(B)(16) for 75°C insulation
• Fuse sizing: NEC 240.4(D) and 125% continuous load rule

Our calculations are as accurate as the data you provide. If you enter correct amperage, wire length, and load type, you’ll get correct recommendations.

What’s the difference between continuous and intermittent loads?

Continuous loads run for 3+ hours at a time. Examples: fridges, lights left on overnight, solar charge controllers.

Intermittent loads run for short periods. Examples: winches (typically <2 minutes), dome lights, horn.

Continuous loads require larger fuses (125% of the load current) to prevent nuisance tripping from heat buildup in the fuse. This is an NEC requirement.

Why does Wire Solved recommend thicker wire than I expected?

Wire Solved optimizes for voltage drop, not just ampacity. If your wire run is long, you need thicker wire to minimize resistance and maintain voltage at the device.

For example:

• 10A load, 5 feet of wire → 16 AWG is fine
• 10A load, 30 feet of wire → 12 AWG recommended (to stay under 5% voltage drop)

If you’re okay with more voltage drop (dim lights, slow devices), you can adjust the tolerance in Advanced Settings.

What voltage drop percentage should I use?

Wire Solved defaults to 5%, which is the NEC recommendation for most applications.

3% or less: Critical circuits (navigation lights, emergency equipment, communication) 5%: General use (lights, accessories, typical automotive) 10%: Non-critical circuits where some dimming is acceptable

Lower percentages require thicker wire but provide better performance.

Can I use Wire Solved for AC voltage?

No. Wire Solved is designed exclusively for DC systems (12V and 24V). AC systems have different considerations including:

• Skin effect (AC current distribution in conductors)
• Power factor and reactive loads
• Different code requirements
• Phase relationships

For AC wiring, consult an electrician or use AC-specific tools.

What about wire bundling and temperature derating?

Wire Solved assumes:

• Single wire runs in open air
• 75°C rated insulation
• Ambient temperature around 25-30°C
• No bundling with other current-carrying conductors

If you’re running wires in conduit, bundled with other hot wires, or in high-temperature environments (engine compartments), you’ll need to derate (use thicker wire). This is an advanced topic - consult NEC Table 310.15(B)(3)(a) or an electrician.

Do I need to account for round-trip wire length?

Wire Solved does this automatically. When you enter “20 feet,” we calculate voltage drop for 40 feet total (positive wire + negative/ground wire).

The shopping list in PDF exports also doubles wire requirements for this reason.

What’s the difference between AWG and mm²?

AWG (American Wire Gauge): US/Canada standard. Counter-intuitive numbering - smaller numbers = thicker wire (16 AWG < 10 AWG < 2 AWG < 1/0 AWG).

mm² (square millimeters): Metric standard (ISO 6722). Logical numbering - larger numbers = thicker wire (1.5 mm² < 6 mm² < 25 mm²).

Wire Solved supports both. Toggle between them in Advanced Settings. We show both values in results so you can shop for either.

System Builder Questions

How do I use the System Builder?

1. Click the “System Builder” tab
2. Click “Add Circuit” button
3. Fill in device details (name, amps, wire length, etc.)
4. Click “Add Circuit” - calculation happens automatically
5. Add more circuits as needed
6. Save your system (third tab: “Saved Designs”)

Your system shows total amperage, total power, circuit count, and the largest wire gauge needed.

Can I export my wiring plan?

Yes, two ways:

JSON Export: Downloads a .json file with all circuit data. Use this to back up your designs or share with others who also use Wire Solved.

PDF Export: Generates a professional PDF with:

• System overview and totals
• Circuit details table
• Shopping list (wire and fuse requirements with quantities)
• Installation notes and safety guidelines

How many circuits can I add?

No hard limit, but performance may slow down with 50+ circuits. For very large systems, consider breaking them into logical subsystems (e.g., “Lighting System,” “Charging System,” “Accessories”).

What are system templates?

Pre-built wiring systems you can load as starting points:

• Overlander Basics: Common vehicle accessories (light bars, fridge, air compressor)
• Solar Power System: Solar panels, charge controller, batteries
• Dual Battery Setup: Isolator, auxiliary battery, charging circuit
• Winch Install: High-current winch with relay circuit

Load a template, then customize it for your specific setup.

Troubleshooting

The calculator says my wire is too small but I already installed it. What now?

First, measure the actual voltage at your device under load:

1. Turn on the device
2. Measure voltage at the battery
3. Measure voltage at the device

If voltage drop is acceptable (<5-10%), your installation may be fine despite the calculator’s recommendation. Real-world conditions sometimes differ from theoretical calculations.

If voltage drop is excessive (device won’t work, dim lights, slow winch), you need to:

• Upgrade the wire to a thicker gauge, or
• Shorten the wire run if possible, or
• Add a relay to reduce wire length from the battery

My lights are dim / device runs slowly. Why?

Most likely excessive voltage drop due to:

• Wire gauge too small for the length of run
• Poor connections (corrosion, loose terminals)
• Undersized ground wire (ground must be same gauge as positive)
• Long wire routes (inefficient path to device)

Use Wire Solved to check if your wire gauge is adequate. Measure actual voltage at the device under load to confirm.

The recommended fuse keeps blowing. What’s wrong?

Do not install a larger fuse. Fuses blow for a reason:

1. Actual load exceeds stated amperage - Measure current with a clamp meter
2. Short circuit - Check for damaged insulation, pinched wires, or incorrect wiring
3. Inrush current - Some devices (motors, compressors) draw high startup current briefly
4. Wrong fuse type - Use slow-blow fuses for motors/compressors, fast-blow for electronics

If startup surge is the issue, you may need a slightly larger fuse, but the continuous rating should still be 125% of the actual continuous load.

Can I use automotive primary wire for all applications?

Automotive primary wire (GPT, GXL, TXL) is fine for most vehicle accessory wiring up to around 50-60A.

For higher currents (winches, inverters, high-power solar), use:

• Welding cable (very flexible, fine stranded)
• Marine tinned cable (corrosion resistant)
• Battery cable (large gauge, high strand count)

Never use solid-core wire in vehicles - vibration will cause fatigue and breakage.

How do I know if my system is 12V or 24V?

Check your battery:

• 12V system: Single 12V battery OR two 12V batteries in parallel
• 24V system: Two 12V batteries in series OR dedicated 24V battery bank

Most passenger vehicles (cars, trucks, SUVs) are 12V. RVs, boats, commercial trucks, and some diesel trucks are 24V.

If unsure, measure with a multimeter at the battery - you should see around 12.6V (12V system) or 25.2V (24V system) when fully charged.

Safety Questions

Is it safe to do my own electrical work?

For low-voltage DC accessories (lights, fans, phone chargers), most people can safely do their own work if they:

• Use the correct wire gauge
• Install fuses at the power source
• Use proper crimping tools and heat shrink
• Route wires away from heat/moving parts
• Test before putting into service

Call a professional for:

• Modifications to factory electrical systems
• High current installations (>100A)
• Structural wiring (homes, buildings)
• Anything you’re not confident doing

Where should I install the fuse?

Always install fuses as close as possible to the power source (battery or distribution panel).

This protects the wire from the power source to the device. If a fuse is installed at the device end, the wire from battery to fuse is unprotected and could cause a fire if damaged.

Use inline fuse holders or fuse panels designed for automotive use.

What wire gauge should I use for the ground?

Ground wire must be the same gauge as the positive wire. Current flows through both wires, so both contribute to voltage drop.

Undersized ground wiring is a common cause of electrical problems.

Can I splice wires?

Yes, but use proper techniques:

• Solder and heat shrink (best for permanent connections)
• Crimp connectors (butt splices, ring terminals) with heat shrink
• Never use twist-on wire nuts (designed for AC, not vibration-resistant)

Avoid splices in high-current circuits when possible. Direct runs are more reliable.

What if I exceed 100 amps?

Installations above 100A require:

• Very large wire (often 2 AWG or larger)
• High-quality terminals and connectors
• Proper cable support and routing
• Circuit protection rated for high interrupt current

At this power level, strongly consider hiring a professional or at minimum, consult with an experienced installer.

Data & Privacy

Do you track my calculations?

No. All calculations happen in your browser. We never see what you’re calculating.

We collect basic anonymous metrics (page views, feature usage) via localStorage on your device. This data never leaves your browser.

What happens to my saved systems?

They’re stored in your browser’s localStorage. They stay on your device until you:

• Manually delete them (via Saved Designs tab)
• Clear your browser data
• Uninstall your browser

We never see your saved systems. They’re yours alone.

Can I use Wire Solved commercially?

Yes. Wire Solved is free for both personal and commercial use. If you’re a professional installer and find it useful, feel free to use it with clients.

We only ask that you don’t:

• Rebrand it as your own tool
• Sell access to it
• Remove attribution

See our open source license for details.

Still Have Questions?

Can’t find your answer here? Visit our Contact page to send us a message.

For learning resources about wire sizing, voltage drop, and 12V electrical systems, check out our Learning section.

Last updated: January 6, 2025