Underground transformers typically come in three configurations.

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Underground transformers are three‑phase devices and can be wired in a few standard ways to match system voltage and grounding needs. Three common configurations are used in practice: delta‑delta, delta‑wye, and wye‑wye. In delta‑delta there is no neutral on either side, which gives a strong fault‑current path and is often used when a neutral isn’t required. In delta‑wye, the primary stays delta and the secondary is wye with a grounded neutral, providing a neutral for single‑phase loads and allowing grounding of the secondary; this is a very common setup for stepping down medium voltages to usable low voltages. In wye‑wye both sides have neutrals and can be grounded, offering a solid neutral reference on both sides but needing neutral conductors and careful coordination. Because these three configurations cover the typical needs of underground distribution—voltage, grounding, and service to single‑phase loads—the statement is true.