I need to feed a 120/208 single phase panel from a 120/208 three phase panel in another building. My question is how to ground my sub panel. I think I just need to run my two hots, neutral and equipment ground and drive a ground rod at the sub panel and seperate my neutral from my equipment ground and bond it to building steel. Is this correct?
120/208 Sub Panel
- Thread starter Samz
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jwelectric
Senior Member
- Location
- North Carolina
Re: 120/208 Sub Panel
250.32 (B) (1) Equipment Grounding Conductor. An equipment grounding conductor as described in 250.118 shall be run with the supply conductors and connected to the building or structure disconnecting means and to the grounding electrode(s). The equipment grounding conductor shall be used for grounding or bonding of equipment, structures, or frames required to be grounded or bonded. The equipment grounding conductor shall be sized in accordance with 250.122. Any installed grounded conductor shall not be connected to the equipment grounding conductor or to the grounding electrode(s).
250.32 (B) (1) Equipment Grounding Conductor. An equipment grounding conductor as described in 250.118 shall be run with the supply conductors and connected to the building or structure disconnecting means and to the grounding electrode(s). The equipment grounding conductor shall be used for grounding or bonding of equipment, structures, or frames required to be grounded or bonded. The equipment grounding conductor shall be sized in accordance with 250.122. Any installed grounded conductor shall not be connected to the equipment grounding conductor or to the grounding electrode(s).
- Location
- Illinois
- Occupation
- retired electrician
Re: 120/208 Sub Panel
OR
OR
- Location
- Illinois
- Occupation
- retired electrician
Re: 120/208 Sub Panel
Also, don't forget that all of the grounded conductors that originate from the "sub-panel" are current carrying conductors for derating purposes. [310.15(B)(4)(b)]
Also, don't forget that all of the grounded conductors that originate from the "sub-panel" are current carrying conductors for derating purposes. [310.15(B)(4)(b)]
Re: 120/208 Sub Panel
In 250.32 (B) (2) "Were an equipment grounding conductor is not ran with the supply to the building or structure".Is this refering to the supply panel I want to feed my sub panel from, or the supply I am going to feed my sub panel with? My feed to the main panel is from a dry type transformer 480 to 120/208.
In 250.32 (B) (2) "Were an equipment grounding conductor is not ran with the supply to the building or structure".Is this refering to the supply panel I want to feed my sub panel from, or the supply I am going to feed my sub panel with? My feed to the main panel is from a dry type transformer 480 to 120/208.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: 120/208 Sub Panel
It is the supply feeders to the sub panel.
This alternative method mention by Don is only allowed where there is no other conductive paths between the supply building and the building being supplied (Where the sub panel is) or where the supplying service is not protected by a ground-fault protection device.
Conductive path's could include water pipes, gas pipes, air, telephone cables, network cables, even CATV cables.
I would think that one or more of the above would be present in an commercial/industrial building or would be installed at a later date which could pose problems in multiple neutral current paths later on.
If this is a new installation then it would be best to install it as you stated in your first post. Keep the grounding conductors separate from the grounded(neutral) conductors, installing a grounding electrode at the separate building.
It is the supply feeders to the sub panel.
This alternative method mention by Don is only allowed where there is no other conductive paths between the supply building and the building being supplied (Where the sub panel is) or where the supplying service is not protected by a ground-fault protection device.
Conductive path's could include water pipes, gas pipes, air, telephone cables, network cables, even CATV cables.
I would think that one or more of the above would be present in an commercial/industrial building or would be installed at a later date which could pose problems in multiple neutral current paths later on.
If this is a new installation then it would be best to install it as you stated in your first post. Keep the grounding conductors separate from the grounded(neutral) conductors, installing a grounding electrode at the separate building.
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