jdr:
Based on your description, it sounds like the transfromer disconnecting means is on the load side of the service disconnecting means.
Section 6-3.2.1 of NFPA 20-1998 provides that the power supply to the fire pump shall not be disconnected when the plant power is disconnected.
Section 6-3.2.2 of NFPA 70-1998 requires the power supply conductors to directly connect the power source to a listed fire pump controller. Exception No. 1 to this requirement permits a single disconnecting complying with basically the same requirements found in Section 695.4(B) of NFPA 70. Where the supply voltage is different from the pump voltage, a transformer is permitted, but the disconnecting means supplying the primary of the transformer must meet the requirements of 695.4(B).
The following is a formal interpretation of Section 6-3.2.2 of NFPA 20:
Question 1:Would 6-3.2.2 be applicable when the power source, to the plant, is a dependable public utility service rated 13,200 volts and the plant disconnect is privately owned?
Answer: Yes
Question 2: Would 6-3.2.2 be applicable when the power source to the plant is a dependable public utility service rated 13,200 volts, and the plant disconnect is privately owned with a plant owned and controlled emergency generator automatically providing power if the utility service is interrupted?
Answer: Yes
If you open the buildings service disconnecting means and it shuts off the power to the fire pump, you are in violation of 695.4. Only a single disconnecting means complying with 695.4(B) is permitted between the power source and the fire pump controller.
