bradbb2005
Member
- Location
- South Carolina
- Occupation
- Electrical Designer
Hello,
I have inherited a design that was designed and sealed by others and I am just looking for some direction and possibly a confirmation to my suspicion. I am in contact with the person who sealed it but awaiting their response.
The design included a 4160D/480Y transformer feeding a switchboard. The transformer is outside and the switchboard is inside. The customer owns the MV switchgear and transformer, metering is done via CT meter on the primary side. The connection to the switchboard is direct. There is no detail for bonding in the design.
The cable schedule calls for Phase, Neutral, and Ground conductors to the SWBD from XFMR. According to the ground diagram, the earth ground was done at the transformer. This is a retrofit so it may not be 100% accurate. My guess is that it is earth grounded at the XFMR and SWBD.
The question that has come up is that the contractor has bonded the ground and neutral at both the SWBD (Factory-installed) and the transformer. It is my belief that this is a code violation and the bond should be removed from one side or the other. Obviously, there are cost impacts with either but it seems to me the ground conductor probably shouldn't have been run between the two and there is a parallel path for current.
One other piece of information is that there is a second tap off of the transformer for a Fire Pump. This is fed via phase and ground conductors.
Any help is appreciated and can provide more info if needed.
TIA
I have inherited a design that was designed and sealed by others and I am just looking for some direction and possibly a confirmation to my suspicion. I am in contact with the person who sealed it but awaiting their response.
The design included a 4160D/480Y transformer feeding a switchboard. The transformer is outside and the switchboard is inside. The customer owns the MV switchgear and transformer, metering is done via CT meter on the primary side. The connection to the switchboard is direct. There is no detail for bonding in the design.
The cable schedule calls for Phase, Neutral, and Ground conductors to the SWBD from XFMR. According to the ground diagram, the earth ground was done at the transformer. This is a retrofit so it may not be 100% accurate. My guess is that it is earth grounded at the XFMR and SWBD.
The question that has come up is that the contractor has bonded the ground and neutral at both the SWBD (Factory-installed) and the transformer. It is my belief that this is a code violation and the bond should be removed from one side or the other. Obviously, there are cost impacts with either but it seems to me the ground conductor probably shouldn't have been run between the two and there is a parallel path for current.
One other piece of information is that there is a second tap off of the transformer for a Fire Pump. This is fed via phase and ground conductors.
Any help is appreciated and can provide more info if needed.
TIA
