3 wire sub feed

TJQ

Member
Location
Covington Kentucky
Occupation
Electrical Contractor
I have a client with an old apartment building being sold. The Home Inspector noted that the sub feeds from the service disconnect to the unit sub panels is 3 wire (two hots, one neutral). Was there a time when this was accepted by the NEC and if so do you know when the code was changed to require a 4 wire sub feed.
Thank You,
 
Last edited:

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
I don't think it was compliant but if the old panel is feed with emt or metal raceway then the home inspector may not realize the conduit could be the equipment grounding conductor.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
If the sub-panel is within the same structure then a 4-wire feeder has been required forever.

Welcome to the Forum. :)
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
Any bets that the subpanels don't have any circuits with grounds, and the installer figured he didn't need to pull a ground to the subpanels?
 

TJQ

Member
Location
Covington Kentucky
Occupation
Electrical Contractor
Has grounds, Home Inspector report actually noted that the grounds and neutrals needed to be separated because it is a sub panel. We were hired to do this and found that it was fed with a 3 wire so isolating the neutral would not help. The option to replace with 4wire sub feeds would cause a lot of drywall damage so customer was hoping this was done per the NEC when it was originally installed to avoid replacing it. I was not aware of a time when a 3 wire was acceptable and it is sounding like this is the case.
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
Has grounds, Home Inspector report actually noted that the grounds and neutrals needed to be separated because it is a sub panel. We were hired to do this and found that it was fed with a 3 wire so isolating the neutral would not help. The option to replace with 4wire sub feeds would cause a lot of drywall damage so customer was hoping this was done per the NEC when it was originally installed to avoid replacing it. I was not aware of a time when a 3 wire was acceptable and it is sounding like this is the case.
OK, I got nuthin'. :unsure: I can't imagine what the original installer was thinking.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
Has grounds, Home Inspector report actually noted that the grounds and neutrals needed to be separated because it is a sub panel. We were hired to do this and found that it was fed with a 3 wire so isolating the neutral would not help. The option to replace with 4wire sub feeds would cause a lot of drywall damage so customer was hoping this was done per the NEC when it was originally installed to avoid replacing it. I was not aware of a time when a 3 wire was acceptable and it is sounding like this is the case.
Then your only recourse is to find the original electrical inspection.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Has grounds, Home Inspector report actually noted that the grounds and neutrals needed to be separated because it is a sub panel. We were hired to do this and found that it was fed with a 3 wire so isolating the neutral would not help. The option to replace with 4wire sub feeds would cause a lot of drywall damage so customer was hoping this was done per the NEC when it was originally installed to avoid replacing it. I was not aware of a time when a 3 wire was acceptable and it is sounding like this is the case.
Feeder needs to be replaced.
 
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