Transformers

What  installation requirements affect transformers in healthcare occupancies?

In accordance with NFPA 70, National Electrical Code, here are some of the key provisions relative to transformers that may have an effect on healthcare occupancies:

• Individual dry-type transformers of more than 112½ kVA rating shall be installed in a transformer room of fire-resistant construction having a minimum fire rating of 1 hour.
• Transformers not over 112½ kVA have no specific installation requirements for the room in which they are located.
• Dry-type transformers rated over 35,000 volts shall be installed in a vault with minimum fire resistance of 3 hours. Each doorway leading into a vault from the building interior shall be provided with a tight-fitting door that has a minimum fire rating of 3 hours. Exception: Where transformers are protected with automatic sprinkler, water spray, carbon dioxide, or halon, construction of 1-hour rating shall be permitted.

Each of the occupancy chapters in NFPA 101®, Life Safety Code®, 2000 edition refer to Section  9.1 for utilities and 9.1.2 for Electric Utilities. Section 9.1.2 states, “Electrical wiring and equipment shall be in accordance with NFPA 70, National Electrical Code [1999 edition], unless existing installations, which shall be permitted to be continued in service, subject to approval by the authority having jurisdiction.”