How Many Amps Is 5 kVA at 277V?

A load with an apparent power of 5 kVA at 277V draws 18.05 amps (single-phase) or 6.02 amps (three-phase). Generators, UPS systems, and transformers publish kVA ratings because the circuit current on the output is set by apparent power, not by the load's real-power draw. This conversion gives you the apparent-power current so you can size breakers and wiring.

5 kVA equals 18.05 amps at 277 volts (single-phase)

18.05 Amps

Three Phase (277V L-N, 480Y/277)6.02 A

Try: 3kVA at 277V 7.5kVA at 277V 2kVA at 277V 1kVA at 277V

kVA

Volts

Amps (1Φ)

18.05

Assumes a single-phase AC circuit at the input voltage. kVA is apparent power, so no power factor term is involved.

Formulas

Single Phase

I_(A) = (kVA × 1000) ÷ V

(5 × 1000) ÷ 277 = 5,000 ÷ 277 = 18.05 A

Three Phase (277V Line-to-Neutral)

I_(A) = (kVA × 1000) ÷ (3 × V_L-N) ≤ equivalent to (kVA × 1000) ÷ (V_L-L × √3)

5,000 ÷ (3 × 277) = 5,000 ÷ 831 = 6.02 A

Applies to 480Y/277 systems where 277V is the line-to-neutral voltage (line-to-line ≈ 479.76V).

Single Phase vs Three Phase

The same 5 kVA unit draws very different current depending on the phase configuration:

Configuration	Formula	Current at 277V
Single Phase	5,000 ÷ 277	18.05 A
Three Phase (277V L-N)	5,000 ÷ (3 × 277)	6.02 A

For this specific case, 5 kVA at 277V, three-phase carries about 66.67% less current per line than single-phase at the same voltage. That gap tracks the 1 ÷ √3 factor for L-L three-phase (or 1 ÷ 3 for L-N), which is why three-phase distribution is common at commercial and industrial scale: the same apparent power rides on smaller conductors and smaller breakers (applies to 480Y/277 systems).

Generator & UPS Sizing

Load-Side Real Power by Power Factor

A load with an apparent power of 5 kVA draws different amounts of real power depending on the load's own power factor. The table below is a load-side conversion, not a forecast of what a generator or UPS will output for that load: generators and UPS units publish their own independent kW rating set by the engine or inverter design, and that rating is often lower than kVA × the load's PF.

Load Type	Load PF	Load Real Power (kW)	Current at 277V
Resistive (heaters, lights)	1.0	5 kW	18.05 A
Mixed typical	0.85	4.25 kW	18.05 A
Motors/HVAC	0.80	4 kW	18.05 A
Computers/servers (no PFC)	0.65	3.25 kW	18.05 A

Note: current draw stays the same across the rows because kVA sets the current, not the load's power factor. PF only affects how much real work (kW) the load does per amp drawn.

Sizing a load against a source. If you are feeding this load from a UPS, generator, or transformer, check the load against both the source's kVA rating AND the source's kW rating. Those are two independent numbers published by the manufacturer. A 10 kVA / 8 kW generator, for example, can supply up to 10 kVA of apparent power AND up to 8 kW of real power, whichever limit is reached first. Do not use the kW figures above as a substitute for the source's published kW rating.

Circuit Sizing: Starting Points

The numbers below are rough order-of-magnitude starting points under typical assumptions (copper conductors, 75°C terminations, short run, no ambient or bundling derates, non-continuous duty). They are not install specs. Actual breaker and wire selection depends on the equipment nameplate, conductor and termination temperature ratings, cable type, run length and voltage-drop target, ambient and bundling conditions, whether the load is continuous, any NEC 430/440 motor or HVAC provisions, and local code.

	Single Phase	Three Phase
Current draw (at full kVA)	18.05 A	6.02 A
Ballpark branch OCP	~20A	~15A

For a real install, run the full wire-size calculator with your actual run length, voltage, and drop target, and verify breaker selection against the equipment nameplate and local code.

Energy Cost at Full Load

A load with an apparent power of 5 kVA at load PF 0.85 draws 4.25 kW of real power. Running cost at that draw: $0.72/hour at $0.17/kWh (rates last reviewed April 2026), or $173.40/month (8h/day). Full breakdown.

kW Equivalent

5 kVA at PF 0.85 = 4.25 kW. See 4.25 kW to amps at 277V.

Other kVA Ratings at 277V

kVA	Single Phase Amps	Three Phase Amps (L-N)	Real Power (PF 0.8)
1 kVA	3.61 A	1.2 A	0.8 kW
2 kVA	7.22 A	2.41 A	1.6 kW
3 kVA	10.83 A	3.61 A	2.4 kW
5 kVA	18.05 A	6.02 A	4 kW
7.5 kVA	27.08 A	9.03 A	6 kW
10 kVA	36.1 A	12.03 A	8 kW
15 kVA	54.15 A	18.05 A	12 kW
20 kVA	72.2 A	24.07 A	16 kW
25 kVA	90.25 A	30.08 A	20 kW
30 kVA	108.3 A	36.1 A	24 kW
40 kVA	144.4 A	48.13 A	32 kW
50 kVA	180.51 A	60.17 A	40 kW

Frequently Asked Questions

How many amps is 5 kVA at 277V?expand_more

5 kVA at 277V is 18.05 amps (single-phase) or 6.02 amps (three-phase (480Y/277)).

What size generator do I need for my loads?expand_more

Generator sizing is not a single-formula calculation. A rough napkin pass is: add up the steady-state watts of everything you plan to run, divide by a planning power factor (often 0.8 but not universal), and add margin. Then cross-check the result against the generator's published kW rating, which is a separate manufacturer spec set by the engine (prime mover) and is not derived from the generator's kVA rating by any formula. The caveats that matter for a real install: motor and compressor inrush can be several times steady-state current, load diversity and sequencing affect peak demand, voltage-dip tolerance of sensitive equipment limits how much motor load a given genset can start, and altitude and ambient temperature both derate output. A load with an apparent power of 5 kVA at PF 0.8 has a real-power draw of 4 kW, but that number alone is not sufficient to size a generator for a real installation.

Why are UPS and generators rated in kVA not kW?expand_more

Because the current on the output (and therefore the conductor, switchgear, and winding sizing) is set by apparent power, kVA = V×I, regardless of the load's power factor. UPS and generator manufacturers publish a separate kW rating in addition to the kVA rating, set by the inverter or engine design, and it is often lower than the kVA rating. You cannot derive a UPS or generator's kW output from its kVA rating and the load's power factor: the two ratings are independent specs and a load has to fit under each of them when sizing against the source.

How much fuel does a 5 kVA generator use?expand_more

Fuel burn is set by the generator's specific-fuel-consumption curve, not a rule of thumb tied to the kVA rating. It varies sharply with fuel type (gasoline vs diesel vs natural gas vs propane), load percentage (partial-load efficiency is much worse than full-load), engine size and age, altitude, and ambient temperature. For a specific unit, check the manufacturer's fuel-consumption curve at your expected load percentage. Generic per-hour estimates from the kVA rating alone are not reliable enough to plan fuel capacity from.

What is the difference between kVA and kW?expand_more

kVA is apparent power (V×I), which sets the current on the circuit and the sizing of conductors, breakers, and windings. kW is real power (the portion that does useful work), equal to kVA×load PF. A load with an apparent power of 5 kVA at load PF 0.8 draws 4 kW of real power. For a source such as a generator or UPS, kVA and kW are two independent manufacturer ratings, not two views of the same spec, and both have to be checked when sizing a load.

This calculator provides estimates for reference purposes only. Always consult a licensed electrician and verify compliance with the National Electrical Code (NEC) and local electrical codes before performing any electrical work.