Does this look right!

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alive wire

Member
Location
Phoenix, AZ US
So this is my first time, there's a disagreement between an electrical engineer and a city electrical inspector ( and I'm stuck here in the Middle With You) about bonding and setup of this Transformer we chose the side of the inspector because we need our Green tag and to get on down the road.
Scared to death that I'm actually saying this to you guys.
But give me your opinion uploadfromtaptalk1464217380603.jpg

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winnie

Senior Member
Location
Springfield, MA, USA
Occupation
Electric motor research
Looks _wrong_ to me.

The supply neutral should not be in the picture at all. It should not be connected to the secondary neutral, and should not be connected to ground.

If the feeder for this transformer originates at the service panel then this might not actually be a problem, but it is not compliant.

-Jon
 
A

alive wire

Member
Location
Phoenix, AZ US
winnie said:
Looks _wrong_ to me.

The supply neutral should not be in the picture at all. It should not be connected to the secondary neutral, and should not be connected to ground.

If the feeder for this transformer originates at the service panel then this might not actually be a problem, but it is not compliant.

-Jon
Click to expand...
That's what the engineer thought , what I thought but the city inspector in buying it.
This run is as follows 277/480 disconnect to 277/480 panel to 30 kva 208/120Y trans to 208/120 panel

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Smart $

Smart $

Esteemed Member
Location
Ohio
Code wise (with extreme emphasis) I do not believe there is any requirement which prohibits a feeder neutral. It makes this transformer a non-SDS. Code offers little specifics on grounding such, but removing what is otherwise the system bonding jumper would make it compliant. The non-compliancy as wired is the connection scheme creates a parallel pathway for neutral current on the equipment grounding system and will require rearrangement of grounding per 250.6...

...But the better alternative is to remove the feeder neutral and make it the transformer secondary an SDS. :happyyes:
 
kwired

kwired

Electron manager
Location
NE Nebraska
alive wire said:
That's what the engineer thought , what I thought but the city inspector in buying it.
This run is as follows 277/480 disconnect to 277/480 panel to 30 kva 208/120Y trans to 208/120 panel

Sent from my SM-N900V using Tapatalk
Click to expand...
Have a picture of the nameplate of the transformer?

If it is delta connected primary (very likely is) there is no function that depends on a primary side neutral. You do need an equipment grounding conductor from the primary though.

If it is a wye primary there could be a need for a primary neutral, more details would be needed to know for certain.
 
A

alive wire

Member
Location
Phoenix, AZ US
kwired said:
Have a picture of the nameplate of the transformer?

If it is delta connected primary (very likely is) there is no function that depends on a primary side neutral. You do need an equipment grounding conductor from the primary though.

If it is a wye primary there could be a need for a primary neutral, more details would be needed to know for certain.
Click to expand...
Kwired and smart $
Thank you , you're right primary neutral should have never been pulled

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A

alive wire

Member
Location
Phoenix, AZ US
winnie said:
Looks _wrong_ to me.

The supply neutral should not be in the picture at all. It should not be connected to the secondary neutral, and should not be connected to ground.

If the feeder for this transformer originates at the service panel then this might not actually be a problem, but it is not compliant.

-Jon
Click to expand...
Winnie
Thank you also, you were first to respond and right on target.
Thanks to all that helped!

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S

Strathead

Senior Member
Location
Ocala, Florida, USA
Occupation
Electrician/Estimator/Project Manager/Superintendent
kwired said:
Have a picture of the nameplate of the transformer?

If it is delta connected primary (very likely is) there is no function that depends on a primary side neutral. You do need an equipment grounding conductor from the primary though.

If it is a wye primary there could be a need for a primary neutral, more details would be needed to know for certain.
Click to expand...

I have never seen a wye primary, I know they exist, but that said, my overfilled brain thinks the common (grounded conductor) point on the Wye primary have to be isolated from the secondary. And a grounding conductor would be allowed to bond to the same primary termination point. So this can't be a Wye primary because it doesn't have a primary common
 
J

jap

Senior Member
Occupation
Electrician
They should have saved that they wasted with pulling in the Neutral that wasn't needed in the primary and used that to size the secondary EGC properly.


JAP>
 
J

jap

Senior Member
Occupation
Electrician
Scratch my last.
When I flip the picture right side up the size of the wire is more evident.

JAP>
 
Smart $

Smart $

Esteemed Member
Location
Ohio
As it is currently wired, the secondary is not isolated, it is a non-SDS, and the EGC is sized based on the supply OCPD rating of the feeder.

Change it to SDS, then it would be undersized at #10, perhaps at #8 depending on actual size of those secondary conductors.
 
A

alive wire

Member
Location
Phoenix, AZ US
Primary conductors are #6, secondary are #1. egc is #6 Dropped the primary neutral today and was green tag , those who wanted a picture of the name plate here it is.
Thank you guys again for all your help!
uploadfromtaptalk1464310669319.jpg

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Smart $

Smart $

Esteemed Member
Location
Ohio
alive wire said:
Primary conductors are #6, secondary are #1. egc is #6 Dropped the primary neutral today and was green tag , those who wanted a picture of the name plate here it is.
Thank you guys again for all your help!
Click to expand...
Ha!

It's a delta wye transformer. Seems to me the only person that could justifiably make this mistake is an apprentice...
 
Smart $

Smart $

Esteemed Member
Location
Ohio
alive wire said:
Smart $ I'm hiring, what do you think about Arizona in June
Click to expand...
I appreciate the offer, but you should know when I last worked, I only worked four to five months a year and made essentially a year's worth of wages. Yes, I put in a lot of overtime in that stretch, and the pay rate was good also. However, because of health issues, I'm currently categorized as disabled according to my doctors and permanently disabled according to social security. I have high hopes of recovering and returning to work, but I'll likely go back to the work I was doing before if I am capable...

...unless you can manage a better offer. :D
 
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