In a three-phase four-wire delta system, what is the B-phase conductor commonly referred to as?

In a three-phase four-wire delta system, the B-phase conductor is commonly referred to as the high-leg. This terminology is used because, in certain configurations of delta systems, particularly when connected to a single-phase load, one of the phase legs (often B-phase) will have a line-to-neutral voltage that is higher than the other phases. This characteristic occurs primarily in grounded delta systems, where the high-leg conductor is typically the phase that is 1.732 times the phase-to-phase voltage, and it is often found in systems where a phase is derived from the transformer secondary tap.

The high-leg is important in electrical distribution because it can affect how loads are connected and how circuits are designed, especially in ensuring balanced loads across phases to prevent overheating and inefficiencies. Additionally, misunderstanding the designation could lead to incorrect wiring practices or safety concerns in electrical installations.