Grounded conductor

[hhsting]

Nec 2014 Article 250.186 mentions grounded conductor. What is grounded conductor?

 

[infinity]

From Article 100:

Grounded Conductor. A system or circuit conductor that is
intentionally grounded.

 

[hhsting]

I apologize but I still don’t follow. In context of NEC 2014 Article 250.186 does grounded conductor mean neutral?

 

[LarryFine]

Yes.

 

[ptonsparky]

Most likely you will not see it on new projects, but a grounded conductor is not necessarily the neutral. Reference 250.186 (3) Delta Connected Service.

 

[infinity]

I apologize but I still don’t follow. In context of NEC 2014 Article 250.186 does grounded conductor mean neutral?

More definitions from Article 100:

Neutral Conductor. The conductor connected to the neutral
point of a system that is intended to carry current under
normal conditions. (CMP-5)

Neutral Point. The common point on a wye-connection in a
polyphase system or midpoint on a single-phase, 3-wire system,
or midpoint of a single-phase portion of a 3-phase delta system,
or a midpoint of a 3-wire, direct-current system. (CMP-5)

Informational Note: At the neutral point of the system, the
vectorial sum of the nominal voltages from all other phases
within the system that utilize the neutral, with respect to the
neutral point, is zero potential.

 

[hhsting]

Now i am really confuse. 250.186 says if grounded conductor is provided could also mean neutral or some other conductor?

 

[ptonsparky]

A grounded conductor is not necessarily a neutral. It can be one of the phases of a delta system. Corner grounded delta.

 

[Dennis Alwon]

1

 

[Dennis Alwon]

Here is an interesting read on transformers-- I certainly need all the help I can get on these as I have never worked on a Delta system before. When I worked in NYC some of the buildings still had DC not AC voltage but I had not seen deltas

https://iaeimagazine.org/magazine/20...unded-systems/

 

[electrofelon]

250.186 is kinda silly the way it is layed out and worded. First, note this is in part X which is over 1000 volts. It is rather odd they use the word "grounded conductor" here for two reasons: 1) I have never heard of a utility having a grounded conductor that wasnt a neutral, and 2) they use the word "neutral" not "grounded conductor" in 250.184. Not sure what is with the inconsistency.

250.186(A) is basically saying bring the MV neutral to the service equipment and bond it, just like a LV service.

250.186(B) probably never happens, this would be where the utility provides you with some sort of "EGC" or bonding jumper that connects to their grounded conductor (neutral) somewhere. up the line. I have never seen or heard of utility doing such a thing.

 

[kwired]

Any conductor that is intentionally grounded is a grounded conductor. Most low volt NEC applications that grounding occurs at either the source or first disconnecting means or at the service equipment. Most the time (per NEC) if there is a neutral conductor and the system is intended to be grounded then the conductor that must be grounded is the neutral conductor. Otherwise systems with no neutral you can ground any conductor of the system - corner delta is popular and another popular system that many forget about is a simple two wire source. Your typical 120 volt control transformer only has two terminals - you can ground either one of them, some may have provisions to make additional connections to one but from theory standpoint there is only two possible places to ground it. That grounded conductor of that two wire system technically isn't a neutral, just a grounded conductor, but many wrongly call it a neutral.