Are you saying the utility is not supplying the correct voltage and a transformer is needed between the pump controller and the primary service disconnect?
Bill Brooks -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Don Lowry Sent: Saturday, April 05, 2014 1:11 PM To: [email protected] Subject: Fire Pump Electrical Service References from NFPA-20 (2010 edition) Situation: Fire Pump to be installed on ESFR system (75 hp) electric motor. 9.2.2 (1) or (5) On down through Chapter 9 to; 9.2.3.4 Where the overcurrent protection permitted by 9.2.3 is installed, the overcurrent protection device shall be rated to carry indefinitely the sum of the locked rotor current of the fire pump motor(s) and the pressure maintenance pump motor( s) and the full-load current of the associated fire pump accessory equipment. OK, so the locked rotor current is 543 amps, plus jockey pump, lights, heat, etc added would require a 600 amp over current protective device. This is what the Engineer and I determined would be the requirement for this dedicated service to the fire pump. When the engineer submitted his electrical service plan (600 amp service) to the city, the City Plan Reviewer states that we don't need a 600 amp service, but rather a 125 amp service. In reading through Article 695.4 of the NEC. It states: "Where the locked rotor current value does not correspond to a standard overcurrent device size, the next standard overcurrent device size shall be used in accordance with 240.6. The requirement to carry the locked rotor currents indefinitely shall not apply to conductors or devices other than overcurrent devices in the fire pump motor circuits." So, does this mean that the service itself (transformer) and related conductors can be per normal size (125 amp) with just a 600 amp fuse in the disconnect before the controller? In 30 + years this is the first time I have ever been asked about this. Before I was only asked about pump size etc , and when installed and checked at pump start-up there was indeed a fuse of appropriate size in the service disconnect. So I assumed all was correct. I'm just wanting to make sure the Engineer and I understand the requirements for the actual electrical service provided. I know it's not my area of expertise, nor my responsibility, just curious. Thanks in advance for any help. Don Lowry, CET, RME (TX) _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
