The Direct Answer: 5 kVA converts to 41.67 amps at 120V (single-phase), 21.74 amps at 230V (single-phase), and 13.88 amps at 208V (three-phase). Because kVA measures apparent power, this conversion depends entirely on your system's voltage and phase configuration. Power factor (PF) is completely irrelevant when converting kVA to amps.
The 5kVA to Amps Conversion Tables
To size your wire and breakers correctly, you must match the 5 kVA load to your specific service voltage. The table below provides the exact amperage for standard North American and international grid voltages. Use this as your primary reference before heading to the electrical supply house.
| System Voltage | Phase Configuration | Calculated Amps (5 kVA) | Standard Application |
|---|---|---|---|
| 120V | 1-Phase | 41.67 A | Standard US residential branch circuits, small UPS systems |
| 208V | 3-Phase | 13.88 A | Commercial office buildings, light data center racks |
| 230V | 1-Phase | 21.74 A | European/UK residential, international IT equipment |
| 240V | 1-Phase | 20.83 A | US residential dryers, HVAC, workshop welders |
| 277V | 1-Phase | 18.05 A | Commercial lighting arrays (line-to-neutral of 480Y) |
| 400V | 3-Phase | 7.22 A | European industrial machinery, heavy commercial HVAC |
| 480V | 3-Phase | 6.01 A | US heavy industrial motors, large transformer primaries |
Transformer and UPS capacities rarely sit at exactly 5 kVA in practice; loads fluctuate. Below is a reference chart showing a ±20% range (4 kVA to 6 kVA) for the two most common single-phase residential and light-commercial voltages.
| Apparent Power (kVA) | Amps at 120V (1-Phase) | Amps at 240V (1-Phase) |
|---|---|---|
| 4.0 kVA | 33.33 A | 16.67 A |
| 4.5 kVA | 37.50 A | 18.75 A |
| 5.0 kVA | 41.67 A | 20.83 A |
| 5.5 kVA | 45.83 A | 22.92 A |
| 6.0 kVA | 50.00 A | 25.00 A |
The Formula and the Power Factor Misconception
The math behind these tables relies on the fundamental relationship between apparent power (kVA), voltage (V), and current (A). The formulas shift slightly depending on whether you are dealing with a single-phase or three-phase supply.
Single-Phase Formula:
Amps = (kVA × 1000) ÷ Volts
Substituted for 5 kVA at 120V: Amps = 5000 ÷ 120 = 41.67 A
Three-Phase Formula:
Amps = (kVA × 1000) ÷ (√3 × Volts)
Substituted for 5 kVA at 208V: Amps = 5000 ÷ (1.732 × 208) = 13.88 A
Why Power Factor (PF) is Irrelevant Here
A frequent mistake on the workbench is attempting to factor in Power Factor (PF) when converting kVA to amps. According to All About Circuits, kVA represents apparent power—the total vector sum of real power (kW) and reactive power (kVAR). Power factor is the ratio of real power to apparent power. Because the kVA rating on a transformer or UPS nameplate already accounts for the phase angle difference between voltage and current, you do not multiply or divide by PF to find the amperage. If your equipment nameplate says 5 kVA, the current draw is fixed strictly by the voltage.
Sizing Breakers and Wire for a 5kVA Load
Knowing the amperage is only half the job; you must now select the correct overcurrent protection and conductor size. Let us assume you are wiring a continuous 5 kVA load (like a server rack UPS or an electric heater) on a 120V single-phase circuit, drawing 41.67 amps.
Safety & Code Caveat: The National Electrical Code (NEC) requires continuous loads (those expected to run for 3 hours or more) to be derated to 80% of the breaker's capacity. Always verify local AHJ requirements, as regional amendments may dictate stricter thermal limits.
1. Breaker Sizing (The 125% Rule):
For a continuous load, multiply the calculated amps by 1.25.
41.67 A × 1.25 = 52.08 A
Since 52.08 A is not a standard breaker size, NEC 240.4(B) allows you to round up to the next standard size. You must install a 60-amp breaker. (If the load is strictly non-continuous, a 45A or 50A breaker may be permissible, but 60A is the safest baseline for UPS systems).
2. Conductor Sizing:
Your wire must handle the 60-amp breaker rating without exceeding its temperature limits.
- THHN in Conduit (75°C column): 6 AWG copper is rated for 65 amps, which safely covers the 60A breaker.
- NM-B Cable (Romex) (60°C column): You must step up to 4 AWG copper. NM-B is legally restricted to the 60°C ampacity column (NEC 334.80), and 6 AWG NM-B is only rated for 55 amps, which is insufficient for a 60A breaker protecting a continuous load.
Frequently Asked Questions
When is the 5kVA to amps conversion meaningless?
The conversion becomes mathematically and practically meaningless in two scenarios. First, if you do not know the system voltage and phase configuration (e.g., you just see "5kVA" on a shipping manifest but don't know if it's a 120V or 480V unit), you cannot resolve the current. Second, if the equipment nameplate actually lists 5 kW (real power) and you mistakenly treat it as 5 kVA. To convert kW to amps, you must know the Power Factor. If the PF is unknown on a kW-rated load, any amperage calculation is a guess and will result in improperly sized, potentially fire-hazardous wiring.
How does the answer shift between 120V, 230V, and 3-phase?
Current and voltage share an inverse relationship for a fixed apparent power. Moving from a 120V single-phase supply to a 230V single-phase supply nearly halves the current draw (from 41.67A down to 21.74A), allowing you to use much thinner, cheaper wire. Shifting to a 3-phase system (like 208V) introduces the √3 (1.732) multiplier in the denominator, which drastically reduces the amperage per leg down to 13.88A. This is why heavy commercial loads are pushed to 3-phase: it minimizes conductor mass and voltage drop over long runs.
Can I use a 50-amp breaker for a 41.67A load at 120V?
Only if the load is strictly non-continuous (runs for less than 3 hours at a time). If it is a continuous load, the NEC 125% rule mandates a minimum circuit ampacity of 52.08A. A 50-amp breaker will eventually nuisance-trip under thermal stress if subjected to a continuous 52A demand, and using it violates code for continuous duty. Always default to the 60-amp breaker for continuous 5 kVA loads at 120V.
