An inverter pulls big DC current — the cable and fuse have to carry it without overheating or dropping voltage. Wattonomy computes the gauge and fuse for any inverter at 12, 24 or 48 V, to ABYC E-11, and shows the working.
Continuous DC current at the inverter’s rated output, 1.5 m run, sized to ABYC E-11 with a 3% voltage-drop limit.
Cable gauge and fuse for common inverters, computed by the engine at a 1.5 m run. Notice how moving to 24 V or 48 V roughly halves (then quarters) the current — and the copper.
| Inverter | 12 V | 24 V | 48 V |
|---|---|---|---|
| 1000 W | 4 AWG90 A · 125 A fuse · 1.9% | 8 AWG44 A · 60 A fuse · 1.2% | 12 AWG22 A · 30 A fuse · 0.8% |
| 1200 W | 2 AWG108 A · 150 A fuse · 1.6% | 6 AWG53 A · 80 A fuse · 0.9% | 10 AWG26 A · 40 A fuse · 0.6% |
| 2000 W | 2/0 AWG179 A · 250 A fuse · 1.5% | 4 AWG89 A · 125 A fuse · 0.9% | 8 AWG44 A · 60 A fuse · 0.6% |
| 3000 W | 269 Astep up V / parallel | 1 AWG133 A · 200 A fuse · 1% | 6 AWG66 A · 100 A fuse · 0.6% |
| 5000 W | 448 Astep up V / parallel | 3/0 AWG222 A · 300 A fuse · 0.7% | 2 AWG110 A · 150 A fuse · 0.4% |
Figures are continuous DC current at rated output over a 1.5 m run, to ABYC E-11 with a 3% voltage-drop limit. On a lithium bank the inverter’s main fuse should be a Class T (high interrupting rating) — the designer sizes the exact Class T and AIC for your battery. Longer runs need a larger cable; size your exact run in the designer.
Inverters draw the highest steady current in the system. Too thin a cable overheats; too small a fuse nuisance-trips, too big a fuse fails to protect. Wattonomy sizes the conductor to carry its fuse and hold voltage-drop under 3%, to ABYC E-11 — and flags when the current is too high for a single cable at that voltage.
Four things decide the gauge and fuse — get them right and the run is safe.
Watts ÷ system voltage ÷ inverter efficiency. Higher system voltage means far less current — and thinner, cheaper copper.
Longer runs drop more voltage, so they need a larger conductor. The table assumes 1.5 m; the designer takes your real length.
Sized to protect the conductor (≤ its ampacity) while carrying the load. On lithium, a Class T gives the interrupting rating the bank demands.
Kept under 3% so the inverter sees full battery voltage — to ABYC E-11.
This table sizes one run. The designer sizes your entire build — battery, inverter, solar, every cable and fuse — and draws the wiring diagram, free.
Open the designerThe build binder is a one-time unlock — no subscription.
At 12 V a 2000 W inverter draws around 180 A continuous, which needs roughly 2/0 AWG and a 250 A fuse over a short run. At 24 V it’s about 90 A (4 AWG); at 48 V about 45 A (8 AWG). Wattonomy sizes it to your exact run length and voltage.
The fuse protects the cable — it must be at or below the conductor’s ampacity while carrying the inverter’s continuous current. On a lithium bank it should be a Class T for its high interrupting rating. The designer computes the exact rating and AIC for your battery.
Power is volts × amps, so at 24 V or 48 V the same wattage draws half or a quarter of the current — and cable size follows current. That’s why big systems move to 24 V or 48 V.
It’s near the practical limit — about 270 A, more than a single sensible cable carries, so you’d need parallel cables or (better) a 24 V or 48 V system. The table shows exactly where that line falls.
Plain version: these are the recognized rulebooks your cable and fuse are sized against, so the numbers hold up to a surveyor, an inspector or an insurer.
Wattonomy applies these standards in its calculations. It is not certified, sponsored or endorsed by ABYC, ISO, NFPA or Victron — it sizes your design to meet what they require, and shows the working.
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