ungrounded???

[ryan_618]

Lets say have no need for a grounded conductor. You install a CT enclosure and run service entrance conductors from the CT to an MDP with a main disconnect inside if it. Your service entrance conductors consist of a brown oragne yellow, no grounded conductor.

After you have done all of that, the power company pulls in the service lateral and they provide a grounded conductor. Does 250.24(B) force you to add a grounded conductor to the service disconnect despite the fact that you have only line-to-line loads?

 

[cs409]

Re: ungrounded???

what is a Combination inspector????

 

[scott thompson]

Re: ungrounded???

Ryan,

PoCo is supplying an AC Service from a Grounded System, so I would have to say the Grounded Conductor is needed to be run to the Service Disconnect, and bonded to it (plus a local GES).

If not, the only fault path is the Earth, which in one way could be good (High Impedance Ground method 99.0334...joke), but mostly it would just suck!

My 2?

Scott

 

[don_resqcapt19]

Re: ungrounded???

Ryan,
Yes, you must bring the grounded conductor from the utility system to the service disconenct and install a main bonding jumper. From that point on you can delete the grounded conductor and install only the phase conductors and EGC. As Scott said you must have a fault clearing path and if you do not install the grounded conductor there is no fault clearing path.
Don

 

[charlie]

Re: ungrounded???

250.24(B) 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 bonded to each disconnecting means enclosure. The grounded conductor(s) shall be installed in accordance with 250.24(B)(1) through (B)(3).

Bottom line Ryan, if it is available, ya gotta take it to each disconnecting means enclosure.

 

[ryan_618]

Re: ungrounded???

Thanks guys. Thats thew way I viewed it as well. Yesterday I did an inspection for a system such as this and I required the grounded conductor, although I based decision on 250.4(B)(4).

what is a Combination inspector????

A combination inspector is one that holds certification in all aspects of a building, such as building, mechanical, plumbing and electrical. I have 7 certifications, so I inspect all aspects of residential/commercial.

 

[charlie]

Re: ungrounded???

Besides all that, CS409, Ryan is one sharp dude.

 

[electricman2]

Re: ungrounded???

The POCO here will supply a grounded or ungrounded service depending on what is requested.

 

[rasmithircgov.com]

Re: ungrounded???

Heres my 2 cents, YES.

 

[ryan_618]

Re: ungrounded???

Thanks Charlie, that was very nice of you.

Just so theres no misconceptions, Charlie is trying to get me to buy him a beer when he gets to Salt Lake for the NFPA meeting.

 

[tom baker]

Re: ungrounded???

I'll buy for both Charlie and Ryan. Its seems like we are running into more building code aspects in the NEC, its nice to get the building code help from Ryan.