40 kVA to Amps
Find current directly from apparent power and line voltage for single and three-phase systems.
A 40 kVA generator or transformer can supply 333.33 Amps on a 120V single-phase circuit, and 166.67 Amps on a 240V single-phase circuit. In three-phase applications, it supports 111.03 Amps at 208V and 48.11 Amps at 480V.
40 kVA is 166.7 A at 240 V single-phase AC. At other common voltages — 208 V: 192.3 A. Use the calculator below for any voltage or circuit type.
For three-phase systems, the current is lower because the power is distributed across three alternating current waves. This relies on the
Amps = (kVA × 1000) ÷ (Volts × 1.732).
| Phase & Voltage | Max Current (Amps) |
|---|---|
| Single-phase 120V | 333.33 A |
| Single-phase 240V | 166.67 A |
| Three-phase 208V | 111.03 A |
| Three-phase 480V | 48.11 A |
How do you convert kVA to amps?
For single-phase, amps = (kVA × 1000) ÷ V. A 10 kVA single-phase supply at 240 V gives (10 × 1000) ÷ 240 = 41.7 A. For three-phase, amps = (kVA × 1000) ÷ (√3 × V): a 10 kVA, 400 V three-phase supply gives 10000 ÷ (1.732 × 400) = 14.4 A.
kVA to Amps Formula
Multiply kVA by 1,000 to convert to VA (volt-amps), then divide by the line voltage. This gives the current in amps for a single-phase system. Example: 5 kVA at 120 V to (5,000) ÷ 120 = 41.67 A.
For three-phase, divide by voltage and the square root of 3 (≈ 1.7321). The √3 factor arises from the 120° phase angle between conductors. Use line-to-line voltage (e.g. 400 V, 480 V). Example: 5 kVA at 400 V to 5,000 ÷ (400 × 1.7321) = 7.22 A.
kVA to Amps Reference Table — Single-phase
| kVA | Amps @ 120 V | Amps @ 240 V |
|---|---|---|
| 1 kVA | 8.3333 A | 4.1667 A |
| 2 kVA | 16.6667 A | 8.3333 A |
| 5 kVA | 41.6667 A | 20.8333 A |
| 10 kVA | 83.3333 A | 41.6667 A |
| 20 kVA | 166.6667 A | 83.3333 A |
| 50 kVA | 416.6667 A | 208.3333 A |
Single-phase vs Three-phase
One live conductor plus a neutral. Power is delivered as a single sinusoidal wave. Common in homes, small offices, and retail units up to around 10 kVA. Higher current per conductor for the same power.
A = (kVA × 1,000) ÷ VThree live conductors, each offset 120° apart. Delivers three times the power at the same current, making it ideal for motors, data centres, and industrial sites. Far more efficient for loads above 10 kVA.
A = (kVA × 1,000) ÷ (V × √3)In practice: a 40 kVA site generator
Forty kVA delivers about 111 A per phase at 208 V, a common temporary-supply size on construction sites. Generators dislike running lightly loaded — sustained operation below roughly 30% of rating causes wet stacking in diesel sets and shortens engine life. Sizing to the actual load rather than the largest imaginable one is genuinely better for the machine, not just cheaper.
Frequently Asked Questions
Multiply kVA by 1,000 and divide by the voltage. For
single-phase: A = (kVA × 1,000) ÷ V.
For three-phase: A = (kVA × 1,000) ÷ (V × √3).
For example, 10 kVA at 240 V single-phase gives
(10 × 1,000) ÷ 240 = 41.67 A.
- Single-phase:
A = (kVA × 1,000) ÷ V - Three-phase:
A = (kVA × 1,000) ÷ (V × √3), where √3 ≈ 1.7321
Note that kVA is apparent power — it does not account for power factor, unlike kW (real power). Use kVA when sizing cables, fuses, and switchgear.
- Single-phase at 240 V: (5 × 1,000) ÷ 240 = 20.83 A
- Three-phase at 240 V (L-L): (5 × 1,000) ÷ (240 × 1.7321) = 12.03 A
Three-phase draws less current per conductor because load is shared across three wires.
Single-phase power uses one live conductor and a neutral, delivering power as a single sinusoidal wave. It is standard in homes and small offices. Three-phase power uses three live conductors, each carrying a wave offset by 120°. For the same kVA, three-phase requires significantly less current per conductor, making it more efficient for large motors, industrial equipment, and commercial buildings.