Fire pumps?

[DARUSA]

Hi!!!
When I need to size the EGC from the fire pump motor control to the pump Do I have to size it based on the Short Circuit protection and table 250.122 or based on the size of the wire?

 

[chris kennedy]

Hi!!!
When I need to size the EGC from the fire pump motor control to the pump Do I have to size it based on the Short Circuit protection and table 250.122 or based on the size of the wire?

Which ever is larger. See 250.122(B).

 

[Smart $]

Which ever is larger. See 250.122(B).

695.6(H) Ground-Fault Protection of Equipment. Ground-fault protection of equipment shall not be permitted for fire pumps.​

Essentially, fire pumps are only permitted to have overcurrent protection. Exactly how to implement no ground-fault protection is not specified.

 

[DARUSA]

695.6(H) Ground-Fault Protection of Equipment. Ground-fault protection of equipment shall not be permitted for fire pumps.
Essentially, fire pumps are only permitted to have overcurrent protection. Exactly how to implement no ground-fault protection is not specified.

Short Circuit and ground fault protection no OP!

 

[DARUSA]

Fire pump EGC

Fire pump EGC

do I have to run a EGC wire type from the first disconnect switch to de motor control or the EMT conduit is ok

 

[chris kennedy]

695.6(H) Ground-Fault Protection of Equipment. Ground-fault protection of equipment shall not be permitted for fire pumps.​

Essentially, fire pumps are only permitted to have overcurrent protection. Exactly how to implement no ground-fault protection is not specified.

We talking apples and oranges here???

Commentary following 695.6(H) in the 08 NECHB;

Ground-fault protection of equipment as specified in several sections of the NEC is not permitted to be used to protect components of a fire pump installation. (The function of ground-fault protection of equipment protection should not be confused with the function of GFCI protection for personnel.) Although the protection afforded to equipment by this type of ground-fault protection is a mandatory safety requirement in certain circumstances, the need for an uninterrupted source of power takes precedence for fire pump installations. See 230.95, Exception No. 2, and 240.13(3).

 

[Smart $]

We talking apples and oranges here???

Pretty much. Grounding for ground-fault purposes is stressed throughout the Code... for safety reasons. However, a ground-fault in a fire pump feeder and subsequent circuits with ground-fault protection could disable the pump when it is needed most, which could have a more catastrophic result.

Commentary following 695.6(H) in the 08 NECHB;

I am uncertain why they threw in the bit about GFCI protection, but the rest pretty much confirms the necessity to not have ground-fault protection. The commentary is rendered even more ambiguous because there is no 230.95 Exception 2.

 

[RUWired]

do I have to run a EGC wire type from the first disconnect switch to de motor control or the EMT conduit is ok

Article 695.6(E) does not list EMT as an approved raceway.

 

[hurk27]

Hi!!!
When I need to size the EGC from the fire pump motor control to the pump Do I have to size it based on the Short Circuit protection and table 250.122 or based on the size of the wire?

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)

Short circuit protection only, except as allowed in 695.5(C)(2) (transformers)


The service feeding a fire pump must 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 when connected to this power supply

If you are supplying from a transformer pay close attention to the requirements in 695.5

Also pay attention to voltage drop requirements in 695.7 and remember if you up size your ungrounded conductors for voltage drop, you have to up-size the EGC. (250.122(B)

Lot of math to do when doing fire pump systems

 

[DARUSA]

Article 695.6(E) does not list EMT as an approved raceway.

yes! ,you right but that is from the motor control to the pump.I am planning to run emt from the electric room DS to the motor control and use a RHH wire that is rated for 2hrs fire rate .Based on -695.6 B 3 and from motor control to the pump RMC with FLMC and a regular THHN wire

 

[DARUSA]

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)


OK but my doubt is if I have to run the EGC of wire type from the motor control to the pump and If I have to tun the EGC (wire type) from the DS inside the electric room to the fire pump motor control?

 

[RUWired]

yes! ,you right but that is from the motor control to the pump.I am planning to run emt from the electric room DS to the motor control and use a RHH wire that is rated for 2hrs fire rate .Based on -695.6 B 3 and from motor control to the pump RMC with FLMC and a regular THHN wire

I was on the understanding that 695.6(B)(1) is concrete encased,(b(2) is a raceway behind a 2 hr fire rated assembly, and (B)3 is a mineral insulated type of cable.

Rick

 

[RB1]

DARUSA,

The electrical circuit protective system you are proposing to use will require an equipment grounding conductor as part of the Listing of the system. It will also require steel fittings.

 

[RB1]

DARUSA,

Let me rephrase my first reply. Check the listing of the electrical circuit protective system you propose to use. Some systems require an RHH type equipment grounding conductor. You must install the circuit protective system according to its listing.

 

[ivsenroute]

695.6(H) Ground-Fault Protection of Equipment. Ground-fault protection of equipment shall not be permitted for fire pumps.​

Essentially, fire pumps are only permitted to have overcurrent protection. Exactly how to implement no ground-fault protection is not specified.

There is a difference between grounding and GFI protection for equipment. This is not GFCI, this is GFI which trips at a higher amperage. The OP was not asking about GFI protection, just equipment grounding. Did I miss something here?

 

[dcspector]

There is a difference between grounding and GFI protection for equipment. This is not GFCI, this is GFI which trips at a higher amperage. The OP was not asking about GFI protection, just equipment grounding. Did I miss something here?

I would go with Chris K's post #2 for the OP's answer. BTW 250.122 (B) is one of the top violations in The District.

 

[augie47]

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 ?

 

[Smart $]

... Did I miss something here?

No, you did not. Though I failed to elaborate such, my statement was for informative purposes only.

However, since you seem willing to discuss the subject, it seems contradictive to not permit ground-fault protection of equipment, yet still require grounding... which would, in many to most circumstances, allow the overcurrent device to open the circuit on a "qualifying" ground-fault.

 

[ivsenroute]

In this case, qualifying would mean a direct short which would be catastrophic vs a GFI for equipment which typically requires more amperage than GFCI protection for personnel.

 

[Smart $]

In this case, qualifying would mean a direct short which would be catastrophic vs a GFI for equipment which typically requires more amperage than GFCI protection for personnel.

Leave GFCI out of the discussion, for I'm well aware of the difference be it and GFP.

Compare, say an ungrounded supply with GFD vs. a grounded supply, both with OCP only. Which pump system would be more reliable in the event of a ground fault during a fire?