600 Amp service and sub panels

[Daniel malack]

I have a meter base approximately 15' from a transformer, a 600 amp fused disconnect connected to meter base, 400' run to residential building panel has 3 200amp breakers, three 200amp runs to panels inside the home. I want to use direct buried cables for the 400'run can I just run 3 wires or do I have to run 4? My inspector is way out in the country so I would need code references.

 

[George Stolz]

You need an equipment grounding conductor. See 250.32(B).

 

[Daniel malack]

(B) Grounded Systems.​

For a grounded system at the separate building or structure, the connection to the grounding electrode and grounding or bonding of equipment, structures, or frames required to be grounded or bonded shall comply with either 250.32 (B)(1) or (B)(2).

(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).
​

(2) Grounded Conductor.

Where (1) an equipment grounding conductor is not run with the supply to the building or structure, (2) there are no continuous metallic paths bonded to the grounding system in each building or structure involved, and (3) ground-fault protection of equipment has not been installed on the supply side of the feeder(s),the grounded conductor run with the supply to the building or structure shall be connected to the building or structure disconnecting means and to the grounding electrode(s) and shall be used for grounding or bonding of equipment, structures,or frames required to be grounded or bonded. The size of the grounded conductor shall not be smaller than the larger of either of the following1) That required by 220.61​

(2) That required by 250.122


Code said, or (B)(2) Where (1) an equipment

grounding conductor is not run with the supply to the building or structure, My brain computes this as if i can run 3 wires, am i making something out of this that isnt there?

​

 

[Smart $]

Code said, or (B)(2) Where (1) an equipment

grounding conductor is not run with the supply to the building or structure, My brain computes this as if i can run 3 wires, am i making something out of this that isnt there?

No... if compliance is to 2005 NEC, which is the edition from which you posted. It was changed in 2008 edition to require an EGC.

PS: Not sure about 2005 edition, but 2008 you would not be able to run standard direct-burial cables in parallel because each would be required to have a full size EGC (not larger than ungrounded conductor).

PPS: According Mike Holt's adoption by state, VA is under 2008.

 

[Daniel malack]

No... if compliance is to 2005 NEC, which is the edition from which you posted. It was changed in 2008 edition to require an EGC.

PS: Not sure about 2005 edition, but 2008 you would not be able to run standard direct-burial cables in parallel because each would be required to have a full size EGC (not larger than ungrounded conductor).

PPS: According Mike Holt's adoption by state, VA is under 2008.

Thanks for your help.

 

[George Stolz]

PS: Not sure about 2005 edition, but 2008 you would not be able to run standard direct-burial cables in parallel because each would be required to have a full size EGC (not larger than ungrounded conductor).

That part is open (a little bit) to interpretation. 300.4 requires all conductors of a circuit to be contained within the same cable or trench. Technically, an inspector could require the EGC of these parallel conductors to be contained within the same cable - that is, literally wound together at the factory. However, a seperate single conductor USE cable could be approved if it is in the same trench in close proximity. It depends on 90.4.

I would be inclined to use parallel sets of DB cables and a single DB EGC in the installation the OP proposed.

 

[Smart $]

That part is open (a little bit) to interpretation. 300.4 requires all conductors of a circuit to be contained within the same cable or trench. Technically, an inspector could require the EGC of these parallel conductors to be contained within the same cable - that is, literally wound together at the factory. However, a seperate single conductor USE cable could be approved if it is in the same trench in close proximity. It depends on 90.4.

I would be inclined to use parallel sets of DB cables and a single DB EGC in the installation the OP proposed.

I don't see it as open. 300.3(B) along with 300.3(B)(1) both use "trench"... but if we are talking multi-conductor cables run parallel in same trench, I don't see 300.3(B)(2) as allowing a single-conductor EGC.