How do you calculate transformer kVA from load current?
For a three-phase load, kVA = voltage × current × 1.732 ÷ 1000. For a single-phase load, kVA = voltage × current ÷ 1000. Enter your load current and system voltage and the calculator does both, then applies any growth margin you specify.
What are the standard transformer sizes?
Common three-phase distribution sizes run 15, 30, 45, 75, 112.5, 150, 225, 300, 500, 750, 1000, 1500, 2000, 2500, 3000, 3750, and 5000kVA. Single-phase sizes run 5, 10, 15, 25, 37.5, 50, 75, 100, 167, 250, and 333kVA. The calculator rounds your load up to the next standard size.
How much headroom should I add for future load growth?
A common practice is 20–25% spare capacity for commercial service equipment, but the right margin depends on your load mix, diversity, and expansion plans. Continuous loads require sizing at 125% per the Article 220 load calculation — this tool does not apply that factor automatically, so include it in your load or growth margin; overcurrent protection per 450.3 is a separate step — confirm with your engineer.
Does kVA depend on power factor?
No — kVA is independent of power factor, which is why transformers are rated in kVA. Power factor matters for real power (kW = kVA × PF) and for current draw of a fixed kW load: a lower PF pulls more current for the same kW.
Can you quote the transformer this calculator recommends?
Yes — Veridian Electric supplies dry-type and liquid-filled transformers sourced to your exact specification from our manufacturer and supply-partner network. Send the recommended size with your request and you will have a firm quote within one business day.
