Fire Pump Metering

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Yes as long as the switch is rated for locked rotor current. In my area the switch would not have to be fused, as long as it has a the correct short circuit rating, non fused switches are typically 10K AIC.
Locked rotor current is typically 6X the running amps of the motor....
A 25 HP motor is normally 34 amps, x 6 is 180 so a 200 amp disconnect may be large enough.
A fire pump is sacrificial in a fire, even if it overloads we don't want the fuses blowing. A fire pump controller has no over load protection
 
It's one place where you need to pay close attention to your Locked Rotor Indicating Code Letter on your nameplate. You will note in Table 430.7(B) its easy to end up with a high Lock Rotor number.
 
augie47 said:
It's one place where you need to pay close attention to your Locked Rotor Indicating Code Letter on your nameplate. You will note in Table 430.7(B) its easy to end up with a high Lock Rotor number.
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You need to use the tables in NFPA 20 (Standard for the Installation of Stationary Fire Pumps for Fire Protection), specifically Table 9.5.1.1(a) and Table 9.5.1.1(b). They list the values to use, which may or may not be the same as in the NEC or on the manufacturer's nameplate.
 
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