Service Conductors from source to Fire Pump Controller

[CJM]

I have researched some of the previous posts and haven't seen any that specifically addressed the service conductors from the power source to the Fire Pump Controller. We have researched the code and don't see anything that specifically addresses the service conductors. Our question is should the service conductors to the control panel (not the branch circuit conductors from the control panel to the fire pump) be sized based on LRA or FLA? We are interpreting the NEC as requiring them to be sized based on FLA. In the September issue of EC&M's "Stumped by the Code" Mike Holt replied to a similar question but he refered to NEC Section 695.6(C)(2) as Branch Circuit Conductor Sizing. Does the same section also apply for the service conductors from the power source to the control panel?

 

[sceepe]

I have researched some of the previous posts and haven't seen any that specifically addressed the service conductors from the power source to the Fire Pump Controller. We have researched the code and don't see anything that specifically addresses the service conductors. Our question is should the service conductors to the control panel (not the branch circuit conductors from the control panel to the fire pump) be sized based on LRA or FLA? We are interpreting the NEC as requiring them to be sized based on FLA. In the September issue of EC&M's "Stumped by the Code" Mike Holt replied to a similar question but he refered to NEC Section 695.6(C)(2) as Branch Circuit Conductor Sizing. Does the same section also apply for the service conductors from the power source to the control panel?

A fire pump must be fed directly from "the source". You can't come out of a switchboard or other panel. So the only thing the source is supplying is the fire pump. That being the case, why would you size the conductors on the line side of the controller differently than on the load side of the controller? The current and operating requirements on either side are identical.

I guess you could have an unual situation but I normally see the controller fed directly from the POCO xfmr and or generator. Sorry my answer is long on opinion and short on CODE.

 

[jtester]

cjm

If I understand your question correctly, you want to know if the service wiring can be sized the same as the wiring on the load side of the controller. I went thru that last week and I believe the answer is yes.

230.90(A) exception No. 4 allows fire pump supply conductors to be protected in accordance with 695.4(B)(1).

Jim T

 

[RB1]

According to the general rule of 695.6, this section applies to power circuits supplying fire pumps. This would include branch circuits, feeder conductors, or service conductors. 695.6(C) provides the rules for sizing these conductors.

 

[pismo]

I'm assuming there is only one motor(jockey pump fed from somewhere else).You would size the service entrance conductors based on the horse power rating and the motor design shown on the motor. Then go to the appropriate table in article 430 and get the ampacity from there. Then add 125% to that. The only time you would size it based on the locked-rotor would be if you put a service (not required) ahead of the controller with an overcurrent protection device in it.

 

[sandsnow]

Our POCO will not serve a building without metering.

A direct connection from the padmount to a Fire Pump controller would not be possible unless the controller included metering equipment. There is also the issue of the meter being accessible to the POCO. They require an outside entrance for metering equipment.

Has anyone ever seen a Fire Pump controller that included POCO metering?

 

[jtester]

Larry

Our utility will install CT metering on the secondary bushings inside the transformer, which then allows for a direct run from the transformer to the controller.

Jim T

 

[sandsnow]

Larry

Our utility will install CT metering on the secondary bushings inside the transformer, which then allows for a direct run from the transformer to the controller.

Jim T

I've seen our POCO install that and primary metering, but it must be under special agreement. I would think there would be extra cost to the customer.

edit: It's done so rarely I forgot about it!

 

[pismo]

I've seen our POCO install that and primary metering, but it must be under special agreement. I would think there would be extra cost to the customer.

edit: It's done so rarely I forgot about it!

The utility here makes us install a CT cabinet for metering equipment. We size that equipment the same as the conductors. I never install an overcurrent device unless it's designed that way or on the plans.