Used 45 kVA Three Phase Isolation Transformer, 240V to 240V, Delta Configuration

Q1. What is a 4-wire 3-phase high-leg delta configuration, and where is it used?

The 4-wire high-leg delta (also called a wild-leg or bastard-leg delta) is a three-phase wiring configuration predominantly used in North America — particularly in the US and Canada — for commercial and light industrial power distribution. It provides 240V three-phase power across all three phases, while also delivering 120V single-phase power between two of the phases and the neutral conductor. This makes it well-suited for facilities that need both three-phase power for motors and machinery, and 120V single-phase power for lighting and general-purpose outlets, from a single transformer. The high-leg phase (typically phase B) carries 208V to neutral and must be clearly identified per NEC requirements, as it cannot be used for 120V single-phase loads.

Q2. Why choose a used isolation transformer over a new unit?

A used isolation transformer at full industrial specification — class H insulation, ≥ 95% efficiency, IP 24 enclosure, and better-than-standard dielectric strength — delivers the same core electrical performance as a new equivalent at a significantly lower purchase price. This makes it a practical choice for replacement installations where a like-for-like swap is needed quickly, budget-constrained projects in manufacturing, commercial construction, or facilities management, and situations where lead time on new equipment is a constraint. The 45 kVA rating and 240V-to-240V same-voltage isolation function are common enough in North American industrial and commercial installations that sourcing a tested used unit represents a viable and cost-effective procurement option.