Do HPS transformers conform to the NEC 451-10 grounding requirements?

All HPS enclosed transformers and reactors can be installed to be compatible with the NEC 451.10 grounding requirements.

A) Dry-Type Transformer Enclosures. Where separate equipment grounding conductors and supply-side bonding jumpers are installed, a terminal bar for all grounding and bonding conductor connections shall be secured inside the transformer enclosure. The terminal bar shall be bonded to the enclosure in accordance with 250.12 and shall not be installed on or over any vented portion of the enclosure.

Exception: Where a dry-type transformer is equipped with wire-type connections (leads), the grounding and bonding connections shall be permitted to be connected together using any of the methods in 250.8 and shall be bonded to the enclosure if of metal.

HPS ventilated low-voltage transformers are typically supplied with pre-installed grounding bars or lugs. If the unit does not have pre-installed lugs, the enclosure is compatible for the user to install the required lugs in accordance with NEC 250.12. It is the installer’s final responsibility to determine if the final installation complied with local code requirements.