Grounded conductor

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donnohpp

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Hello All,
I have a 13.8 Delta to a 480V Y transformer feeding 480V street lighting. I have connected the XO to the grounding grid system that is permissible to use to ground the system, there is a factory bonding strap from the XO to transformer. I also have attached at the transformer EGC. I pulled all ungrounded circuit conductors plus the EGC to a 480V panel and attached the EGC to the grounding bar. All lighting is 480V. I have no line to Neutral loads. The Inspector said I still need to pull a Neutral conductor.
Whats up with that?
 
donnohpp said:
Hello All,
I have a 13.8 Delta to a 480V Y transformer feeding 480V street lighting. I have connected the XO to the grounding grid system that is permissible to use to ground the system, there is a factory bonding strap from the XO to transformer. I also have attached at the transformer EGC. I pulled all ungrounded circuit conductors plus the EGC to a 480V panel and attached the EGC to the grounding bar. All lighting is 480V. I have no line to Neutral loads. The Inspector said I still need to pull a Neutral conductor.
Whats up with that?
Click to expand...

Refer to 250.24(C) for the details, but essentially it requires you to bring a grounded conductor to the service disconnecting means.

However, if the service disconnecting means is on the primary-side of the transformer, your transfomer would be an separately derived system and the neutral would not be required for the secondary.

On the other side of the coin, you are not required to run an EGC on the line side of the service disconnecting means. Instead, you can use the grounded conductor or its terminals as a means for grounding and bonding. So if the service disconnect is on the secondary side of the transformer, you may be able to convert your EGC to a neutral (dependent on size, ampacity, color, and so forth). Regarding its size, it will need to be at least as large as the minimum size grounding electrode conductor per 250.66?see details in 250.24(C)(1).
 
If this is street lighting, not supplied by the customer, then the grounded conductor(neutral if you will) is installed to the lighting fixture and bonded to all metallic parts, including the manhole covers/shrouds.

The grounded conductor is the ground fault current path for utility provided lighting poles.
 
Could I consider this installation as a separately derived system and leave as is? The 13.8 Primary is feed from the Substation and the transformer itself has fuses on the Primary. The Sec. 480 Panel has a Main breaker installed. Since I have grounded and bonded at the transformer if I pulled the neutral it would not be utilized and waste of material.
 
Maybe I am completely misunderstanding the installation??

If you are supplying street lighting from the secondary of the transformer, and it is supplied as utility companies supply them, then the grounded conduuctor is the ground fault current path, which gets bonded to all metallic portions of the install and is required to be installed with the ungrounded conductors.

If not, and I am misunderstanding the install, you will need to install another means for fault current, which would most likely be an EGC.
 
Pierre C Belarge said:
Maybe I am completely misunderstanding the installation??

If you are supplying street lighting from the secondary of the transformer, and it is supplied as utility companies supply them, then the grounded conduuctor is the ground fault current path, which gets bonded to all metallic portions of the install and is required to be installed with the ungrounded conductors.

If not, and I am misunderstanding the install, you will need to install another means for fault current, which would most likely be an EGC.
Click to expand...
Pierre,

While I am not familiar with street lighting installations, it sounds as though you are asking if the installation falls under NESC or NEC... Perhaps you should resolve unknowns in that regard first, 'cause the questions you are asking and the comments you are providing are even confusing me!

Providing this installation falls under NEC purview, donnohpp needs to provide us first with one detail of major importance to how this "service" is wired... and that is: Where is the "service" disconnect???

He has already stated there are fuses on the primary. That implies there is also a disconnect on the primary. If that disconnect is customer operable, that would qualify as the service disconnecting means (SDM) and the transformer would then be an SDS... and no neutral need be pulled to the 480V secondary panel.

If there is no customer operable disconnect on the primary, then the main OCPD of the 480V panel would be the SDM, and donnohpp would have to pull the neutral or convert the existing EGC to a neutral (as mentioned in my first post).

In summary, we have two questions that need answered:
  1. Is this an NESC or NEC installation?
  2. Is the SDM on the primary or secondary side of the transformer?
 
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Smart $ said:
Pierre,

While I am not familiar with street lighting installations, it sounds as though you are asking if the installation falls under NESC or NEC...
In summary, we have two questions that need answered:
  1. Is this an NESC or NEC installation?
  2. Is the SDM on the primary or secondary side of the transformer?
Click to expand...


I am guessing this is an NESC installation.
The disconnect would not be a question if this is an NESC question.

It would be nice to have more info...it is not uncommon in this forum to have many unanswered questions, so we shoot in the dark a lot of times.;)
 
bonding lighting system

bonding lighting system

If it is for street lights. It could just be a city requirement so they can cover their butts when someone touches a light pole and gets shocked. this was the case in Columbus Ohio. But they are right. You always need a ECG at the disconnecting means. But I also only have one more word on this. AHJ
 
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