695 fire pumps

[Zane Bailey]

695 requires that the OC devices within the fire pump controller be rated to carry the locked rotor current of the fire pump motor. I have a 250 hp fire pump motor that is connected ahead of the Main service in its own section, there are no other OC devices ahead of the fire pump controller. The locked rotor current of a 250 hp is something like 1825 amps.
The fire pump controller has a data plate that rates the controller at 250 hp. The controller also has a transfer switch. Both the normal power and emergency power OC devices are rated at 400 amp.
Is this correct? The controller is UL listed and rated at 250 hp, but the 400 amp breakers do not appear to be rated high enough for the 1825 amp locked rotor current.

I do not believe they E power breaker is required to be rated for Locked rotor current.

I believe the normal power does?

 

[augie47]

Art 695 appears to address LR current when discussing individual sources of power but does not seem to address it on multiple sources. Unsure if that's the answer but worth consideration.

 

[Zane Bailey]

695 fire pumps

Art 695 appears to address LR current when discussing individual sources of power but does not seem to address it on multiple sources. Unsure if that's the answer but worth consideration.

Thank you for your reply.

My question is specific to OC devices within the fire pump controller not being rated high enough for the Locked rotor current, but the horse power rating on the controller data plate being rated correctly???

 

[infinity]

The FP controller can be rated in HP to correspond with the pump. The normal feeder OCPD needs to comply with 600% of the FP current allowing a run time of two minutes or the locked rotor current.

 

[Zane Bailey]

695 code references

695 code references

The FP controller can be rated in HP to correspond with the pump. The normal feeder OCPD needs to comply with 600% of the FP current allowing a run time of two minutes or the locked rotor current.

Thank you for reply. I agree. Several Manufacturers .i.e Cummins, Eaton quote the 600%. Can you give 695 code references for the 2 min run time?

 

[gadfly56]

Thank you for reply. I agree. Several Manufacturers .i.e Cummins, Eaton quote the 600%. Can you give 695 code references for the 2 min run time?

I don't recall seeing anything about a particular run time. As far as NFPA 20 is concerned, they want the pump to run come hell or high water, and if the pump blows up while doing it's job, that's OK.

The LR current is for OCPD's upstream of the controller. Don't worry about what the controller guys put in their box, they know what they are doing.

 

[gadfly56]

I don't recall seeing anything about a particular run time. As far as NFPA 20 is concerned, they want the pump to run come hell or high water, and if the pump blows up while doing it's job, that's OK.

The LR current is for OCPD's upstream of the controller. Don't worry about what the controller guys put in their box, they know what they are doing.

OK, for the alternate overcurrent protection method I see that's new for 2014. That'll teach me not to keep up.

 

[infinity]

Take a look at 695.4(B)(2) which gives you the 600% or locked-rotor current options.

695.4(B)(2)(a)(2) Overcurrent protection shall be provided by an assembly listed for fire pump service and complying with the
following:
a. The overcurrent protective device shall not open
within 2 minutes at 600 percent of the full-load
current of the fire pump motor(s)695.4(B)(2)(a)(2)

 

[victor.cherkashi]

Take a look at 695.4(B)(2) which gives you the 600% or locked-rotor current options.

NEC-2008, 695.4(1) OCD to carry indefinitely locked rotor current

Sent from my Nexus 5 using Tapatalk

 

[Zane Bailey]

Thank you all for your reply

Thank you all for your reply

I guess I should have mentioned that the facility is a new Hospital, and that the project design is based on the 2005 CEC/NEC.

The Normal power supply is tapped ahead of the service Main in its own vertical section without an OCPD. The fire pump motor is 250 hp, LR current is equal to something like 1825A. The listed combination fire pump controller and power transfer switch is rated 250 hp. The OCPDs within the controller for the Normal power are 400A, which is sized much lower than the LR of the 250 hp fire pump motor. I do realize that this is a "Listed" controller.

this question resurfaced when the Short Circuit Coordination study modeled and provided Coordination settings for the 400A OCPDs which are in the pump motor circuit within the listed fire pump controller.

There seems to be some differences in options on this thread.

Is there a code reference in the 2005 code cycle or NFPA 20, that requires the OCPD devices within the fire pump controller and within the motor circuit to be rated for the LR current of the fire Pump motor, or is the listed fire pump with OCPDs in the pump motor circuit lower than pump motor LRA sufficient to be accepted as compliant?

 

[Zane Bailey]

2010 NFPA 20

2010 NFPA 20

OK, for the alternate overcurrent protection method I see that's new for 2014. That'll teach me not to keep up.

thanks for your reply

I see now that in the 2010 NFPA 20 10.4.4 (1)(a) the breaker required and permitted within the controller, must be of the time delay type and have a tripping time between 8 and 10 seconds at locked rotor current.

Interesting though, the breaker in question has GFP capability. The coordination study provided settings for this function. The study is now Being revised to deactivate the GFP for these devices. Per 695, GFP is not permitted for fire pump equipment. I called the Mfr. (ABB) and they agree it would have been better that the trip units provided should not have had adjustable GFP capability or fixed GFP capability. With some trip units a GFP setting of off does not defeat the GFP function, but leaves the device in the lowest possible GFP setting range. I have started a case with ABB and they will verify Monday that a setting of off in fact disables the GFP function.

Thanks again