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Electrical Room Protection

There seems to be much confusion concerning the fire protection and enclosure requirements for electrical rooms. Do rooms containing circuit breaker circuit breaker, electric device that, like a fuse, interrupts an electric current in a circuit when the current becomes too high. The advantage of a circuit breaker is that it can be reset after it has been tripped; a fuse must be replaced after it has been used  panels or transformers need to be enclosed in fire-resistive enclosures? Do these rooms require sprinklers, or should sprinklers be eliminated in these rooms?

Electrical rooms are not listed as hazardous areas in Chapter 8 of NFPA NFPA National Fire Protection Association
NFPA National Food Processors Association
NFPA National Fluid Power Association
NFPA National Federation of Paralegal Associations (Edmonds, WA) 
 101®, Life Safety Code®, or in sections 3.2, "Protection from Hazards," in each occupancy chapter. Rather, the requirements for enclosures in electrical rooms are found in NFPA 70®, National Electrical Code The National Electrical Code (NEC), or NFPA 70, is a U.S. standard for the safe installation of electrical wiring and equipment. It is part of the National Fire Codes series published by the National Fire Protection Association (NFPA). ® (NEC (NEC Corporation, Tokyo,, An electronics conglomerate known in the U.S. for its monitors. In Japan, it had the lion's share of the PC market until the late 1990s (see PC 98).

NEC was founded in Tokyo in 1899 as Nippon Electric Company, Ltd.

NEC Article 450.21 "Dry-Type Transformers Installed Indoors," requires that dry-type transformers rated larger than 112-1/2 kVA be installed in a transformer room of fire-resistive construction. In this Article, the term "fire-resistive" means a one-hour fire resistance. The door to this room would be a 45-minute fire-protection-rated, self-closing, latching door.

Dry transformers over 35,000 volts must be enclosed in a vault. Vault construction, which is addressed in Article 450.42, requires a threehour fire-resistance rating A fire-resistance rating typically means the duration for which a passive fire protection system can withstand a standard fire endurance test. This can be quantified simply as a measure of time, or it may entail a host of other criteria, involving other evidence of functionality or , although an exception permits a one-hour fire-resistive enclosure where the transformer is protected with a fixed extinguishing system, such as sprinklers, or a gaseous agent extinguishing system.

NEC Article 450.26 addresses oil-insulated transformers installed indoors. Such transformers may be installed in buildings of Type I or II construction if the transformer is rated 35,000 volts or less, no combustible com·bus·ti·ble
Capable of igniting and burning.

A substance that ignites and burns readily.
 materials are stored in the area, a liquid confinement area is provided, and the installation complies with all restrictions provided for in the listing of the liquid. oil-insulated transformers can also be installed indoors if they are protected with an automatic fire extinguishing system and a liquid confinement area, provided the transformers are rated 35,000 volts or less. And oil-insulated transformers can be installed in a vault. Unless the transformer is rated at less than 112-1/2 kVA, however, the vault must be constructed of reinforced concrete reinforced concrete

Concrete in which steel is embedded in such a manner that the two materials act together in resisting forces. The reinforcing steel—rods, bars, or mesh—absorbs the tensile, shear, and sometimes the compressive stresses in a concrete
 at least 4 inches (10 centimeters) tthick. If the transformer's nominal voltage is less than 600, a vault is not required if arrangements have been made to prevent a transformer oil Transformer oil is usually a highly-refined mineral oil that is stable at high temperatures and has excellent electrical insulating properties. It is used in oil-filled transformers, some types of high voltage capacitors, fluorescent lamp ballasts, and some types of high voltage  fire from igniting other materials and if the total capacity in one location does not exceed 10 kVA in a section of the building classified as combustible or 75 kVA where the surrounding structure is classified as fire-resistant construction.

Electrical equipment A piece of electrical equipment is a machine, powered by electricity and usually consists of an enclosure, a variety of electrical components and often a power switch. Examples of Electrical Equipment
  • Cathodic protection rectifier
  • Fire alarm panel
 other than the transformers covered in Article 450 containing more than 10 gallons (38 liters) of flammable flam·ma·ble  
Easily ignited and capable of burning rapidly; inflammable.

[From Latin flamm
 oil per unit must meet the requirements of Parts II and III of Article 450, which may require a fire-resistive enclosure.

There are also special requirements for special electrical installations, such as charged-particle-accelerating equipment and surface mining equipment.

So if rooms containing typical circuit breaker panels and small dry transformers do not require any special fire-resistive enclosures, what about sprinklers in these rooms?

Section of NFPA 13, Installation of Spunkier Systems, requires sprinklers in all spaces in a building protected with sprinklers, including electrical rooms. According to according to
1. As stated or indicated by; on the authority of: according to historians.

2. In keeping with: according to instructions.

 section, however, sprinklers may be eliminated in electrical rooms if the room is dedicated solely to electrical equipment; only dry-type electrical equipment is used; the equipment is installed in a two-hour fire-rated enclosure including protection for penetrations; and no combustible storage is permitted in the room.

In general, typical electrical rooms containing circuit breaker panels and dry transformers do not require a special fire-resistive enclosure, but electrical rooms in sprinklered buildings do require sprinklers. However, special high-voltage electrical equipment and oil-filled equipment may require additional protection in accordance with the NEC.
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Author:Chip Carson
Publication:NFPA Journal
Date:Sep 1, 2008
Previous Article:Fire Extension
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