Concrete encased

[hhsting]

I have incoming utility feeds into CUSTOMER owned transformer. The transformer secondary conductors feed to fire pump and switchboard. The secondary conductor come into switchboard and on separate vertical section the line side is tapped and from switchboard separate compartment tap line side go into building to 100 feet away to first disco means and another 10 feet to fire pump controller and to fire pump.

I have inspector telling me that I need to place conductors from the switchboard tap to the LINE side of fire pump first disconnecting means in concerte encased min 2 in thick. 100 feet of cables.

I looked at NEC 2014 and did not find anything. Anything that comes close is 695.6(A)(2) but it says conductors on load side of first disco but inspector is requiring from tap to line side first disco.
I do not know where inspector is getting this. Which code article section would apply?

 

[WIMaster]

Not 100% sure I am understanding what you are saying here, but it sounds like the AHJ is looking to keep your fire pump "service" conductors "outside of the building" by way of concrete.
A one line including buildings on the drawing would help clear things up.

 

[hhsting]

Not 100% sure I am understanding what you are saying here, but it sounds like the AHJ is looking to keep your fire pump "service" conductors "outside of the building" by way of concrete.
A one line including buildings on the drawing would help clear things up.

But inspector wants to put in concrete encased are customer owned transformer secondary conductor tap to fire pump line side disco. Where it says in NEC they need to be in concerte encased?

Sent from my SM-G935U using Tapatalk

 

[packersparky]

I have incoming utility feeds into CUSTOMER owned transformer. The transformer secondary conductors feed to fire pump and switchboard. The secondary conductor come into switchboard and on separate vertical section the line side is tapped and from switchboard separate compartment tap line side go into building to 100 feet away to first disco means and another 10 feet to fire pump controller and to fire pump.

I have inspector telling me that I need to place conductors from the switchboard tap to the LINE side of fire pump first disconnecting means in concerte encased min 2 in thick. 100 feet of cables.

I looked at NEC 2014 and did not find anything. Anything that comes close is 695.6(A)(2) but it says conductors on load side of first disco but inspector is requiring from tap to line side first disco.
I do not know where inspector is getting this. Which code article section would apply?

Two things are at play here.
#1: If this is not a multi building campus style complex, the power source has to be one of the sources listed in 695.3(A)(1), (2), or (3). Unlikely that (2) would apply so that leaves (1) or (3). (1) is a separate utility service only for the fire pump or from a connection ahead of the service disconnecting means. (2) is a feeder that is derived from a connection as described in (1). If the transformer is customer owned, the connection is not from a service and would be a violation.

#2: Power wiring. For service conductors they have to be protected per 695.6(A)(1) which requires the conductors to be outside the building or installed in accordance with 230.6(1) or (2) which is under 2 inches of concrete under a building or encased in 2 inches of concrete. For feeders they have to be either outside of a building or installed using one of the methods in 695.6(A)(2)(d)(1) through (3)

(d) Inside of a Building. Where routed through a building,
the conductors shall be installed using one of the following
methods:
(1) Be encased in a minimum 50 mm (2 in.) of concrete
(2) Be protected by a fire-rated assembly listed to achieve
a minimum fire rating of 2 hours and dedicated to the
fire pump circuit(s)
(3) Be a listed electrical circuit protective system with a
minimum 2-hour fire rating

 

[hhsting]

Two things are at play here.
#1: If this is not a multi building campus style complex, the power source has to be one of the sources listed in 695.3(A)(1), (2), or (3). Unlikely that (2) would apply so that leaves (1) or (3). (1) is a separate utility service only for the fire pump or from a connection ahead of the service disconnecting means. (2) is a feeder that is derived from a connection as described in (1). If the transformer is customer owned, the connection not from a service and would be a violation.

#2: Power wiring. For service conductors they have to be protected per 695.6(A)(1) which requires the conductors to be outside the building or installed in accordance with 230.6(1) or (2) which is under 2 inches of concrete under a building or encased in 2 inches of concrete. For feeders they have to be either outside of a building or installed using one of the methods in 695.6(A)(2)(d)(1) through (3)

(d) Inside of a Building. Where routed through a building,
the conductors shall be installed using one of the following
methods:
(1) Be encased in a minimum 50 mm (2 in.) of concrete
(2) Be protected by a fire-rated assembly listed to achieve
a minimum fire rating of 2 hours and dedicated to the
fire pump circuit(s)
(3) Be a listed electrical circuit protective system with a
minimum 2-hour fire rating

For feeders 695.6(A)(2)(d) says 695.6(A)(2)(d)(1) to 695.6(A)(2)(d)(3) apply only on supply conductor load side of final disconnecting means fire pump. I got to do conductor concrete encased on line side of disco to switchboard tap per inspector.

 

[packersparky]

For feeders 695.6(A)(2)(d) says 695.6(A)(2)(d)(1) to 695.6(A)(2)(d)(3) apply only on supply conductor load side of final disconnecting means fire pump. I got to do conductor concrete encased on line side of disco to switchboard tap per inspector.

I don't think your power supply to the fire pump is compliant to begin with, and any conductors supplying the fire pump have to be installed in accordance with 695.6(A)(1) or (2) both of which require extra protection of the conductors or be that they be installed outside of the building.

 

[WIMaster]

Weather the customer owns the transformer or not is a moot point, lots of Big customers own thier own MV XFMRS and need to protect the secondary conductors by one means or another regardless.
Is there an OCPD for the fire pump conductors located at the XFMR? It doesn't sound like it hence the one line diagram request.
Based on the information you have given us I would agree with Packersparky.

 

[WIMaster]

More: Most XFMRs provide a separately derived system that gets treated like a new service generally speaking.
Fire pumps are treated specially as they are intended to save lives and run full tilt until they die regardless of how bad things are in the building so concrete encased, Mineral insulated cable ect. etc. is the norm for feeding these.

 

[hhsting]

More: Most XFMRs provide a separately derived system that gets treated like a new service generally speaking.
Fire pumps are treated specially as they are intended to save lives and run full tilt until they die regardless of how bad things are in the building so concrete encased, Mineral insulated cable ect. etc. is the norm for feeding these.

Is the part most customer owned Xfmr provide system that gets treated like a new service in NEC?

 

[hhsting]

More: Most XFMRs provide a separately derived system that gets treated like a new service generally speaking.
Fire pumps are treated specially as they are intended to save lives and run full tilt until they die regardless of how bad things are in the building so concrete encased, Mineral insulated cable ect. etc. is the norm for feeding these.

Nec 2014 defintion of separately derived system says: "An electrical source, other than a service, having no direct connection(s) to circuit conductors of any other electrical source other than those established by grounding and bonding connections"

So if I have transformer lets say 480/277V to 208/120V thats customer owned but the primary is fed from electric utility service then that transformer and its secondary conductors are not separately derived and are service conductors?

 

[packersparky]

Nec 2014 defintion of separately derived system says: "An electrical source, other than a service, having no direct connection(s) to circuit conductors of any other electrical source other than those established by grounding and bonding connections"

So if I have transformer lets say 480/277V to 208/120V thats customer owned but the primary is fed from electric utility service then that transformer and its secondary conductors are not separately derived and are service conductors?

No. They are transformer secondary conductors. A typical transformer that you describe does not have any direct connection between between the primary and the secondary.