Fire Pump Power Supply (02/06/2000)
Mike, NEC Section 695-3 states that the electric motor-driven fire pumps shall have a "reliable source of power" from one of the following:
1. Separate Electric Utility Service, or
2. On-Site Power Production Facility, or
3. Onsite Generator
At our facility, the fire pump is connected directly to the utility transformer (ahead of and not within the same cabinet, enclosure, or vertical switchboard section as the service). Couldn't the power for the fire pump motor be disconnected at the transformer by the electric utility in the event of a fire? Is this connection ahead of the service considered a suitable and reliable source of power?
Most modern fire departments bring water pumpers to the fire and since most buildings requiring a sprinkler system, have a pump hose hook up outside of the building for the fire department, thus enabling them to disconnect the electricity to the facility without endangering personnel sent there to extinguish the fire. Therefore, the fire pumps on site only have to try to contain the fire until fire department personnel arrive.
That's what I have been told, by the Chicago Fire Department.
While the installation does meet the requirements of the NEC, it may not be the safest way to feed the fire pump. The NEC states that it is not a design specification and sometimes we need to go beyond what is required to assure an adequate installation. In this instance, it would seem that a label might be a good idea " DANGER THIS TRANSFORMER SERVES THE FIRE PUMP!" I know it is not NEC required, but I have had inspectors recommend things like this and in most cases, I have complied. A good idea is a good idea, and anything that makes it safer would be a good idea.