I had quite the lengthy disagreement with inspector today about a 200 amp feed through panel with 6 breaker spaces. I came off the bottom lugs with 4/0 SER (150 amp per 60 degree column) and went to a 150 amp main breaker panel. She tried saying that they were tap conductors. I said no way. There is no way the SER will ever see more than 150 amps cause it has a main breaker. Can someone else chime in on this please.
Inspector disagreement with 200 amp feed through
- Thread starter rhovee
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jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
Pretty sure inspector is right.
You are tapping the 200 Amp panel with 150A conductors.
Depending on the length you may be okay since the conductors terminate in a OCPD that matches.
240.21(B)(2) assuming a length not greater than 25'.
You are tapping the 200 Amp panel with 150A conductors.
Depending on the length you may be okay since the conductors terminate in a OCPD that matches.
240.21(B)(2) assuming a length not greater than 25'.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
The whole idea of a tap conductor is that it is protected at the far (load) end rather than at the upstream (supply) end.
You say that your SER is protected by the 150A breaker at the far end. That would normally make it a tap. Even if it goes through the 200A main breaker on the feed through panel it is not protected at its rated ampacity at the supply end.
Being a tap does not make it illegal, it just subjects it to a bunch of restrictions.
But if it does not go through the main breaker at the first panel it is actually a service conductor and subject to much different rules. Among other things it can be protected at the far end, but it cannot run inside the building (very far.)
In particular that the 150A disconnect be grouped with the main disconnect at the first panel.
You say that your SER is protected by the 150A breaker at the far end. That would normally make it a tap. Even if it goes through the 200A main breaker on the feed through panel it is not protected at its rated ampacity at the supply end.
Being a tap does not make it illegal, it just subjects it to a bunch of restrictions.
But if it does not go through the main breaker at the first panel it is actually a service conductor and subject to much different rules. Among other things it can be protected at the far end, but it cannot run inside the building (very far.)
In particular that the 150A disconnect be grouped with the main disconnect at the first panel.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
I agree as described it's definitely a tap. Increase the conductors to 200 amps and then you're OK.
mopowr steve
Senior Member
- Location
- NW Ohio
- Occupation
- Electrical contractor
So what part got you?
Is the length over 25'? Otherwise it's still possibly OK
Did the 200amp panel have a Main or not. If not since it was a 6 circuit panel did the feed thru lugs take you past the 6 disconnect rule?
Is the length over 25'? Otherwise it's still possibly OK
Did the 200amp panel have a Main or not. If not since it was a 6 circuit panel did the feed thru lugs take you past the 6 disconnect rule?
flatlander
Senior Member
- Location
- Diamond bar, CA , Tempe AZ
Is this residential. At what point does the rule that says the conductors need not be larger than the service entrance.
- Occupation
- Licensed Electrician
That's been debated before. Disjointed code sections make it hard to come up with a clear answer. 338 tells us to size using 60 degree. Some other code section I can't remember says the part about nothing needing to be bigger than the service entrance conductor size. It all breaks down into a chicken and egg argument.
Residential or not has no bearing.
If there is no main in the 200A feed-thru panel, where all load breakers are service disconnecting means, the feed-thru would just be a service entrance conductor tap with no length limit. However, the two-to-six grouping rule would prevent any substantial distance to the tap OCPD.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
With no length limit *outside the building*.
That qualification comes not from a tap rule but from the service conductors rules.
curt swartz
Electrical Contractor - San Jose, CA
- Location
- San Jose, CA
- Occupation
- Electrical Contractor
I'm 99% sure the service panel the OP is describing does have a main breaker. Its actually a pretty common Combination Service Entrance Device in my area. Meter socket with 200 amp main breaker that feeds 6-8 breaker slots and a set of lugs to feed another panel. The lugs are on the load side of the main breaker.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
That may be true but the protection must be at the origin of the conductors- with some exceptions. I am assuming the main panel has a 200 amp overcurrent protective device. If so and this is not a tap conductor then it is not compliant.
Strathead
Senior Member
- Location
- Ocala, Florida, USA
- Occupation
- Electrician/Estimator/Project Manager/Superintendent
Pardon me for my ignorance. Why are you using the 60 degree table for the conductor rating? Using the 75 degree table I believe your conductors comply with code.
- Occupation
- Licensed Electrician
Art. 338 says you have to use 60 degree. It was not always that way. That is also part of what I was alluding to in my post about feeders not being required to be larger than service conductors.
Strathead
Senior Member
- Location
- Ocala, Florida, USA
- Occupation
- Electrician/Estimator/Project Manager/Superintendent
The OP didn't say it was embedded in insulation, however, I wasn't aware of this change in the 2011 code, so that covers my ignorance part. Second, an inspector could allow the use of 31.15(B)(7) for this cable. I can also see an inspector denying that table, and I certainly wouldn't try to argue too much, but it is part of the feeder between the main breaker and the branch and feeder circuits that feed the dwelling unit.
flatlander
Senior Member
- Location
- Diamond bar, CA , Tempe AZ
Why would you ever make someone use a size larger than the service entrance wires for a dwelling.
So what if there are some loads not carried by that cable. It's still lesser load.
So what if there are some loads not carried by that cable. It's still lesser load.
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