240v 3 phase delta. One phase is grounded. I am tapping off that system and putting in a fused disconnect. Two phases on fuses and the grounded phase labeled white not fused. Since the grounded phase and the grounding conductor were bonded in first disconnect do I do bond them together again in the 240v delta step up 480v delta transformer and to building steel. And since the 240v is grounded do I need to ground a phase on the 480v secondary and if so how would I do that in the step up transformer.
240v grounded 3 phase
- Thread starter casjos
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No. 250.24(A)(5) still applies.. The grounded and grounding remain seperate..
You can either ground one phase of the 480 output following the rules in 250.30, or you can make it an ungrounded system and comply with 250.21(B)
mark32
Senior Member
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- Currently in NJ
Why label the phase that has been grounded white? This conductor is not acting as a neutral, it's a phase conductor and an eg yes?
jumper
Senior Member
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- 3 Hr 2 Min from Winged Horses
It is not a neutral, as you said, but it is a grounded conductor so I think identification is required per 200.6.
I believe it is still a phase conductor, yet it is still grounded. Not a EGC at all.
I believe it is still a phase conductor, yet it is still grounded. Not a EGC at all.
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- Licensed Electrician
Corner grounds freaked me out the first time I saw one because I was so used to having a smaller voltage to ground than phase to phase.
mark32
Senior Member
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- Currently in NJ
Jumper, you are correct. Even though the grounded conductor in this case is not functioning as a neutral it still must be identified as one. I tried uploading a great graphic from iaei.org but it's too large and I don't know how to resize it, so here's the link to a most informative article
http://www.iaei.org/magazine/2002/01/installations-and-inspections-of-corner-grounded-systems/
http://www.iaei.org/magazine/2002/01/installations-and-inspections-of-corner-grounded-systems/
kwired
Electron manager
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- NE Nebraska
People get confused with this in part because they don't always use the correct terminology. Many think of the 'white' as 'neutral'. Often times it is but there are times when it is not.
NEC refers to it as a 'grounded conductor' for good reason. It is the conductor that is grounded. It does not always have to be 'neutral' to all other conductors of the system. Even a two wire transformer secondary does not have a 'neutral' but one conductor usually needs to be 'grounded'.
mark32
Senior Member
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- Currently in NJ
Exactly, that's why I am always mindful of the difference when making posts on here. On the other hand, when talking with the unexperienced I find that they get even more confused when you start using the term grounded conductor.
kwired
Electron manager
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- NE Nebraska
That is what the difference is between professionals and novices. A journeyman or higher level electrical worker, designer, engineer, etc. should know what a 'grounded conductor' is. There are many that don't. Majority of them seldom or never work on anything but 120/240 single phase also. They need to stay away from other systems if they are not willing to learn more about them. The basic concepts are still the same however you just need to understand what you have.
ptonsparky
Tom
- Occupation
- EC - retired
Grounded conductor:thumbsup:
kwired
Electron manager
- Location
- NE Nebraska
Grounded conductor is the terminology used by the NEC. Conductor on some systems that is grounded is not necessarily a "neutral"
It sure helps to understand the NEC better if you use the same terminology it is written with.
It sure helps to understand the NEC better if you use the same terminology it is written with.
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