What is the number of bushings on the low side of a 2400/4160Y-120/240, 50 Kva transformer?

The correct answer is three bushings on the low side of a 2400/4160Y-120/240, 50 KVA transformer. The configuration of this transformer indicates that it has a three-phase design with a wye (Y) connection on the primary side, which typically utilizes three bushings. The secondary side (120/240V) is also a wye configuration for typical residential service. In these configurations, two bushings are generally used for distributing the 120/240V lines, while one bushing serves as a neutral. This arrangement occurs because a wye connection allows the neutral point to be accessible, leading to a total of three bushings being necessary on the low side to accommodate the configuration properly.

The other options do not align with standard transformer design where a wye connection is utilized. For example, two bushings would not be sufficient to provide the necessary phases and neutral, while four or five bushings exceed the requirements for a system designed to operate under those voltage configurations. Therefore, recognizing that a three-phase system typically requires three bushings, with one dedicated to the neutral, reinforces understanding of transformer configurations and wiring practices.