XO on secondary

[jbolen]

I have 15000 incoming and 380 secondary Y ( this is in Afghanistan).

We have 8 sets of 500 mcm (240mm) feeding a 3000 amp switchgear. I know what to do in the gear for as bonding and grounding.

Question is ...This local EE say we do not have to bond XO to the frame of the transformer or bring grounding conductors with our 8 sets 0f 500 in this cable try.

I'm saying OX should be grounded and bonded to the case of this big transformer.

 

[A/A Fuel GTX]

The system bonding jumper connection can be made at the transformer or at the first disconnecting means but not at both locations. Check out 250.30

 

[Twoskinsoneman]

I have 15000 incoming and 380 secondary Y ( this is in Afghanistan).

We have 8 sets of 500 mcm (240mm) feeding a 3000 amp switchgear. I know what to do in the gear for as bonding and grounding.

Question is ...This local EE say we do not have to bond XO to the frame of the transformer or bring grounding conductors with our 8 sets 0f 500 in this cable try.

I'm saying OX should be grounded and bonded to the case of this big transformer.

I believe you can wire it like that (not bonding at TRANS case) but you still have to run an equipment bonding jumper connected from the TRANS case to the grounded conductor where the grounded conductor is connected to ground.

250.30(A)(1)

(1) System Bonding Jumper. An unspliced system bonding
jumper in compliance with 250.28(A) through (D) that
is sized based on the derived phase conductors shall be
used to connect the equipment grounding conductors of the
separately derived system to the grounded conductor. This
connection shall be made at any single point on the separately
derived system from the source to the first system
disconnecting means or overcurrent device, or it shall be
made at the source of a separately derived system that has
no disconnecting means or overcurrent devices.

250.30(A)(2)

(2) Equipment Bonding Jumper Size. Where an equipment
bonding jumper of the wire type is run with the derived
phase conductors from the source of a separately derived
system to the first disconnecting means, it shall be
sized in accordance with 250.102(C), based on the size of
the derived phase conductors.

 

[Pierre C Belarge]

IF the secondary side of the transformer is the service to the structure, then you will need to bond X/O and bring grounded conductors to the structure as per 250.24(C).
Of course, this also depends on whether or not the system is a grounded system.

 

[Twoskinsoneman]

IF the secondary side of the transformer is the service to the structure, then you will need to bond X/O and bring grounded conductors to the structure as per 250.24(C).
Of course, this also depends on whether or not the system is a grounded system.

I thought I would post 250.24(C).
I don't see where it says you have to bond at the TRANS. It says if it is grounded you have to run the grounded conductor to the service disconnect. IMO it does not infer you cannot make the bond at the disconnect...

(C) Grounded Conductor Brought to Service Equipment.
Where an ac system operating at less than 1000 volts
is grounded at any point, the grounded conductor(s) shall
be run to each service disconnecting means and shall be
connected to each disconnecting means grounded conductor(
s) terminal or bus. A main bonding jumper shall connect
the grounded conductor(s) to each service disconnecting
means enclosure. The grounded conductor(s) shall be installed
in accordance with 250.24(C)(1) through (C)(3).