8 AWG to mm²
8 AWG (10 mm²) is the charging-circuit gauge. It is what most camper builders run between the alternator DC-DC charger and the battery, from 40–50 A MPPT controllers to the bank, and as the feed for a small 500 W inverter. It marks the crossover point in termination technique: ring terminals now need a proper crimper instead of pliers, and blade fuses give way to MIDI bolt-down fuses.
All values on this page assume copper conductors at 20°C ambient. Aluminum has ~60% higher resistance for the same cross-section and is generally not recommended for low-voltage DC.
Calculate for your specific cable run
The tables below assume 8 AWG (10 mm²) copper. Use the calculator to confirm this gauge is correct for your exact load and length, or get a different gauge recommendation if needed.
= 60W
= 16.4 ft (one way, round-trip calculated automatically)
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Round-trip voltage drop for 8 AWG (10 mm²) copper wire at 20°C ambient. Cells highlighted in yellow exceed the 3% target; red cells exceed 5% and are not recommended.
| Current | 1 m / 3 ft | 3 m / 10 ft | 5 m / 16 ft | 7 m / 23 ft | 10 m / 33 ft |
|---|---|---|---|---|---|
| 10 A | 0.036 V (0.30%) | 0.11 V (0.89%) | 0.18 V (1.48%) | 0.25 V (2.08%) | 0.36 V (2.97%) |
| 20 A | 0.071 V (0.59%) | 0.21 V (1.78%) | 0.36 V (2.97%) | 0.50 V (4.15%) | 0.71 V (5.93%) |
| 30 A | 0.11 V (0.89%) | 0.32 V (2.67%) | 0.53 V (4.45%) | 0.75 V (6.23%) | 1.07 V (8.90%) |
| 40 A | 0.14 V (1.19%) | 0.43 V (3.56%) | 0.71 V (5.93%) | 1.00 V (8.31%) | 1.42 V (11.87%) |
| 50 A | 0.18 V (1.48%) | 0.53 V (4.45%) | 0.89 V (7.42%) | 1.25 V (10.38%) | 1.78 V (14.83%) |
8 AWG Voltage Drop at 24V DC
Round-trip voltage drop for 8 AWG (10 mm²) copper wire at 20°C ambient. Cells highlighted in yellow exceed the 3% target; red cells exceed 5% and are not recommended.
| Current | 1 m / 3 ft | 3 m / 10 ft | 5 m / 16 ft | 7 m / 23 ft | 10 m / 33 ft |
|---|---|---|---|---|---|
| 10 A | 0.036 V (0.15%) | 0.11 V (0.45%) | 0.18 V (0.74%) | 0.25 V (1.04%) | 0.36 V (1.48%) |
| 20 A | 0.071 V (0.30%) | 0.21 V (0.89%) | 0.36 V (1.48%) | 0.50 V (2.08%) | 0.71 V (2.97%) |
| 30 A | 0.11 V (0.45%) | 0.32 V (1.33%) | 0.53 V (2.23%) | 0.75 V (3.12%) | 1.07 V (4.45%) |
| 40 A | 0.14 V (0.59%) | 0.43 V (1.78%) | 0.71 V (2.97%) | 1.00 V (4.15%) | 1.42 V (5.93%) |
| 50 A | 0.18 V (0.74%) | 0.53 V (2.23%) | 0.89 V (3.71%) | 1.25 V (5.19%) | 1.78 V (7.42%) |
What is 8 AWG (10 mm²) used for?
Camper / RV applications
- DC-DC (B2B) chargers at 40–50 A — Victron Orion, Renogy, Redarc
- MPPT solar controllers 40–50 A to battery
- Inverter feeds up to 500 W at 12V (~50 A burst)
- Main feed from battery to a 6–12 way fuse block
- Alternator charge lines on van conversions
Boat / marine applications
- Shore-power charger output to house bank (40–60 A chargers at the limit)
- House bank to distribution panel on daysailers
- High-output bilge or washdown pump feeds
- Trolling motor leads on small setups (40–50 A)
- Alternator-to-battery on stock 50–60 A alternators
Off-grid / solar applications
- PV combiner to charge controller on 40–50 A arrays
- Battery to inverter for 400–500 W loads
- Cabin main feed from battery cabinet to DC panel
- Wind turbine feeds on small turbines
When to step up
- Continuous current above 40 A — within 20% of ampacity
- Inverter feeds above 500 W at 12V
- DC-DC chargers above 50 A output
- Cable runs longer than 5 m at 12V with currents above 30 A
Fuse size for 8 AWG (10 mm²)
The fuse must protect the wire, not the load. For 8 AWG copper (10 mm²) the maximum fuse rating is 50 A. Below this ceiling, size the fuse at 125% of your continuous load current and round up to the next standard fuse size.
| Continuous Load | 125% Calculation | Recommended Fuse | Fuse Type |
|---|---|---|---|
| 10 A | 12.5 A | 15 A | Blade (ATC) |
| 15 A | 18.75 A | 20 A | Blade (ATC) |
| 20 A | 25 A | 25 A | Blade (ATC) |
| 35 A | 43.75 A | 50 A | MAXI Blade |
| 45 A | 56.25 A | 50 A | MAXI Blade |
Related conversions
Frequently Asked Questions
What is 8 AWG in mm²?
8 AWG is precisely 8.37 mm² by the IEC formula. The standard metric pairing is 10 mm² — the next stocked size up. The VoltPlan calculator uses 10 mm² (50 A ampacity) as the metric equivalent of 8 AWG.
How many amps can 8 AWG wire handle?
8 AWG copper (10 mm²) is rated for 50 A continuous at 20°C in chassis wiring — the standard rating for RV, marine, and off-grid DC systems. It is the typical gauge for 40–50 A charging circuits.
What size fuse for 8 gauge wire on a 12V system?
Maximum fuse for 8 AWG is 50 A. Below that ceiling, size at 125% of continuous load and round up: a 30 A DC-DC charger takes a 40 A fuse, a 40 A MPPT takes a 50 A fuse. At 40–50 A use MIDI bolt-down fuses — blade fuses top out at 30 A reliably.
Is 8 AWG enough for a 1000W inverter?
No. A 1000 W inverter at 12V draws ~85 A continuous — 8 AWG is rated 50 A. Use 4 AWG (25 mm², 85 A) for a 1000 W inverter at 12V. 8 AWG covers inverters up to ~500 W at 12V, or up to ~1000 W at 24V where the current halves.
Can I use 8 AWG for a DC-DC charger?
Yes — 8 AWG is the standard gauge for 40–50 A DC-DC chargers like the Victron Orion XS 50 A or Redarc BCDC1250D. Keep the run short (under 5 m one-way) and fuse both ends at 50 A, since both the starter and house battery can feed a fault.