Grouch1980
Senior Member
- Location
- New York, NY
This is an excerpt from the 2011 NYC amendments to the NEC. It mentions how to size the transformer to the pump, if the pumps voltage is different from the service, and also how to size the primary side OCPD.
(A) Transformers. Where the service or system voltage is different from the utilization voltage of the fire pump motor, a transformer protected by disconnecting means and overcurrent devices shall be permitted to be installed between the system supply and the fire pump controller in accordance with the following.
(1) Size. Transformers shall be rated at a minimum of 125 percent of the sum of the fire pump motor(s) and pressure maintenance pump(s) motor loads, and 100 percent of the remaining load supplied by the transformer. 73 NYC 2011 Electrical Code Technical Provisions
(2) Overcurrent Protection. Primary disconnecting means and overcurrent devices shall be selected in accordance with 695.4(B)(1). Secondary disconnecting means and overcurrent devices shall not be permitted.
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(A)(2) above refers you to 695.4(B)(1). Which is this:
(1) Utility Service. Fire pumps and limited service fire pumps shall have overcurrent protection selected as to allow the operation of the fire pump for as long as the fire pump remains capable of running, except where direct connection is made in accordance with 695.4(A)(3) Exception 1:
(1) Fire Pump. Fire pump overcurrent protection shall be selected at between 300 percent and 600 percent of motor full load current.
(2) Limited Service Fire Pump. Limited service fire pumps shall be protected by overcurrent devices selected at 150 percent of motor full load current. The next larger available device size may be used where selection results in a non-standard device size.
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My question is: (A)(2) above doesn't even mention sizing the OCPD on the generator end; it only refers to 695.4(B)(1)... which is 'utility service', which I posted between the 2 lines. So, if you have a transformer between the generator and the fire pump, I'm assuming I size the OCPD based on 695.4(B)(2), which is 'generator supply'?
(A) Transformers. Where the service or system voltage is different from the utilization voltage of the fire pump motor, a transformer protected by disconnecting means and overcurrent devices shall be permitted to be installed between the system supply and the fire pump controller in accordance with the following.
(1) Size. Transformers shall be rated at a minimum of 125 percent of the sum of the fire pump motor(s) and pressure maintenance pump(s) motor loads, and 100 percent of the remaining load supplied by the transformer. 73 NYC 2011 Electrical Code Technical Provisions
(2) Overcurrent Protection. Primary disconnecting means and overcurrent devices shall be selected in accordance with 695.4(B)(1). Secondary disconnecting means and overcurrent devices shall not be permitted.
____________________________________
(A)(2) above refers you to 695.4(B)(1). Which is this:
(1) Utility Service. Fire pumps and limited service fire pumps shall have overcurrent protection selected as to allow the operation of the fire pump for as long as the fire pump remains capable of running, except where direct connection is made in accordance with 695.4(A)(3) Exception 1:
(1) Fire Pump. Fire pump overcurrent protection shall be selected at between 300 percent and 600 percent of motor full load current.
(2) Limited Service Fire Pump. Limited service fire pumps shall be protected by overcurrent devices selected at 150 percent of motor full load current. The next larger available device size may be used where selection results in a non-standard device size.
____________________________________
My question is: (A)(2) above doesn't even mention sizing the OCPD on the generator end; it only refers to 695.4(B)(1)... which is 'utility service', which I posted between the 2 lines. So, if you have a transformer between the generator and the fire pump, I'm assuming I size the OCPD based on 695.4(B)(2), which is 'generator supply'?