100 watts is 0.83 amps at 120 V or 0.42 amps at 240 V. See the circuit guidance and formula.
| Input | Result |
|---|---|
| 100 W at 120 V | 0.83 A |
| 100 W at 240 V | 0.42 A |
| 100 W at 12 V | 8.33 A |
0.83 amps at 120 V, or 0.42 amps at 240 V. At 12 V (car/RV) it draws 8.33 A.
No — a 15 A / 120 V circuit supplies up to 1800 W, so 100 W leaves 1700 W of headroom (80% continuous-load rule: keep it under 1440 W).
For AC loads with motors or electronics, real amps = watts ÷ (volts × PF). A 1500 W motor at PF 0.8 on 120 V draws 1500 ÷ 96 = 15.6 A, not 12.5 A.