Fire pumps?

[Cold Fusion]

The supply conductors from the controller to the pump motor are sized @ 125% of the FLA of the motor. and this is the size wire you will use in table 250.122 see 695.6(C)(2) ...

hurk -
I'm confused on your intent. T250.122 doesn't use a wire size to size the EGC. T250.122 uses the "Rating or Setting of Automatic Overcurrent Device"

cf

 

[DARUSA]

My brain cells are inactive this morning. I've read this a number of times and have confused myself.
Is there any reason the equipment grounding conductor to the fire pump has to be a wire conductor or can any of the means listed in 250.118 (provided its an acceptable Art 695 raceway) be used ?
If a conductor is used, is it not based on the overcurrent device per 250.122 as with other circuits ?

I have confused myself too! Because the Fire pump that I have for wiring is a 40 hp 3phase 208 volts I will size the wire 115% of the FLC based on the Table 430.250 of the NEC +100% FLC of the jockey pump., The Short-Circuit Protection based on the table 430.251.

40hp 208 volt 114amps (based table 430.250)
115% =131amp
310.16 table=#1/0 wire

SCP 800 amps

Now how do I choose the size of my grounding wire? Do I have to size it based on the 800 amp SCP (Table 250.122)#1/0 or based on the wire size #2 (131 amps" rated of the motor" ) or no wire at all?

 

[DARUSA]

Correction

Correction

Sorry is 125% not 115
It come-up 141amps + 10 amps of the Jockey pump = 151amps
I will use a # 2/0 wire

 

[Smart $]

Wire-type EGC, if run, is required to be sized based on your OCPD rating, or trip setting, using Table 250.122.

 

[DARUSA]

Wire-type EGC, if run, is required to be sized based on your OCPD rating, or trip setting, using Table 250.122.

That will make the wire as the same size of the phase conductors!!!
I will use a piece of 2" LFMC is it ok as a grounding equipment conductor for the 800 amps SCP ? I have clear idea that I can't use this size of FLMC as a ground path.

 

[augie47]

800 amp OCPD would require a 1/0 cu and I don't believe LFMC can be used as a EGC above 60 amps.

 

[hurk27]

hurk -
I'm confused on your intent. T250.122 doesn't use a wire size to size the EGC. T250.122 uses the "Rating or Setting of Automatic Overcurrent Device"

cf

Yea didn't think about that?

So without a OCPD unless it is fed from a transformer, do we size the EGC from the locked rotor amprage? or from the short current amprage?

This never came up before since we used RMC in the last one I did

 

[DARUSA]

Yea didn't think about that?

So without a OCPD unless it is fed from a transformer, do we size the EGC from the locked rotor amprage? or from the short current amprage?

This never came up before since we used RMC in the last one I did

No Mather of the RMC I 'm sure you had to used a piece of FLMC to connect the RMC to the pump . The RMC isn't in direct contact to the motor for that if we have to size EGC based on the SCP the FLMC not will be aceptable for be used as EGC.