Question about tap rules and panel wiring

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cdherman

Member
My colleague and I have been in a quandry about an installation that we were confronted with.

There is a 200 A main service panel with a 100 A panel next to it. The two panels are connected with steel conduit, about 6" apart.

The second panel (I am purposely not useing the term sub here) is fed from a 100A breaker from the main, #2 AL wire and also has a #3 copper to the neutral bar, as well as #6 Cu to the ground bar. It has a bare #6 going outside to earth ground as well.

Here's where it gets tricky -- the neutral and ground are bonded in the second panel and the neutral and ground wires are randomly attached.

There are no feed through lugs on the main panel.

So -- can a panel which meets distance and wire protection requirements for a tap through be wired in this manner? It seems like the second panel meets all the requirements of a tap through installation, except for the use of a breaker in the main panel as the feed.

Maybe I don't get it. I have read about this in great detail. I am mostly in carpentry so you can fairly tell me to get an electriction, but unfortunately, we are getting different opinoins from them as well.

This is my first post -- I've been a reader here for years though and really appreciate all the sound discussions that I have read. Thanks in advance....
 

infinity

Moderator
Staff member
Location
New Jersey
The tap rules would apply if your subpanel had a 90 amp OCPD protecting the #2 AL conductors which have an ampacity of 90 amps. The grounding and grounded conductors need to be separated at the subpanel. If the #6 GEC to the ground rod is not an auxiliary electrode it would need to terminate in the 200 amp service panel on the neutral bus.
 

1793

Senior Member
My colleague and I have been in a quandry about an installation that we were confronted with.

There is a 200 A main service panel with a 100 A panel next to it. The two panels are connected with steel conduit, about 6" apart.

The second panel (I am purposely not useing the term sub here) is fed from a 100A breaker from the main, #2 AL wire and also has a #3 copper to the neutral bar, as well as #6 Cu to the ground bar. It has a bare #6 going outside to earth ground as well.

Here's where it gets tricky -- the neutral and ground are bonded in the second panel and the neutral and ground wires are randomly attached.

There are no feed through lugs on the main panel.

So -- can a panel which meets distance and wire protection requirements for a tap through be wired in this manner? It seems like the second panel meets all the requirements of a tap through installation, except for the use of a breaker in the main panel as the feed.

Maybe I don't get it. I have read about this in great detail. I am mostly in carpentry so you can fairly tell me to get an electriction, but unfortunately, we are getting different opinoins from them as well.

This is my first post -- I've been a reader here for years though and really appreciate all the sound discussions that I have read. Thanks in advance....
If the sub-panel is fed with a breaker as stated in OP then how is this a "Tap" issue?

The tap rules would apply if your subpanel had a 90 amp OCPD protecting the #2 AL conductors which have an ampacity of 90 amps. The grounding and grounded conductors need to be separated at the subpanel. If the #6 GEC to the ground rod is not an auxiliary electrode it would need to terminate in the 200 amp service panel on the neutral bus.
Agreed
 

cdherman

Member
So, just so I understand things completely: If the second panel was fed from feed through lugs instead of the breaker, it would have been a tap through, right?

And, if a second panel is a tap through installation, does it, or does it NOT have to have the ground and neutral separated?

I had understood tap through panels to be wired identical to main panels, in that neutral and ground are bonded together.

It might be easier for us in the long run to make the second panel a tap through from the meter box, as opposed to separating the neutral and ground in it, assuming that it is OK to bond neutral and gound in tap through situations..... The second panel is wired fine enough, but there is not enough extra wire to move things around from one side to the other.....
 

jwjrw

Senior Member
I think he is asking if a disconnect for a transformer can be fed from a tap conductor why cant a panel.
 

jwjrw

Senior Member
I only mentioned it because the OP asked about a tap. The obvious answer to correct the violation would be to change the 100 amp OCPD ahead of the #2 Al feeder with a 90 amp OCPD.
And to unbond it in the subpanel seperate neutral and grounds.....
 

cdherman

Member
And to unbond it in the subpanel seperate neutral and grounds.....
First, it will be easier for us to get rid of the Al wire and replace with #2 copper. That would remedy the 90A versus 100 A issue. The wires between the two boxes are less than 3 feet. I will do that.

Unbonding the neutral and ground are more problematic, as there are wires in the box that are going to be too short. I assume we can add a second ground bar bolted to the box and bond it to the main ground lug with some #6 for good measure. If that is acceptable, then I might be able to unbond the neutral and gound.....

Otherwise, it gets messy, with lots of external boxes to splice on longer pieces of wire to avoid splices in the panel box.

Finally, I still am curious how a second panel is supposed to be wired under tap through rules (and I accept that you are telling me is NOT our situation). But I'd still like to understand it -- are neutral and gound bonded in the box in a tap through install or not? Seems like they would be.
 

augie47

Moderator
Staff member
Location
Tennessee
First, it will be easier for us to get rid of the Al wire and replace with #2 copper. That would remedy the 90A versus 100 A issue. The wires between the two boxes are less than 3 feet. I will do that.

Unbonding the neutral and ground are more problematic, as there are wires in the box that are going to be too short. I assume we can add a second ground bar bolted to the box and bond it to the main ground lug with some #6 for good measure. If that is acceptable, then I might be able to unbond the neutral and gound......
good plan. adding ground bars is often the solution.
Otherwise, it gets messy, with lots of external boxes to splice on longer pieces of wire to avoid splices in the panel box.

Finally, I still am curious how a second panel is supposed to be wired under tap through rules (and I accept that you are telling me is NOT our situation). But I'd still like to understand it -- are neutral and gound bonded in the box in a tap through install or not? Seems like they would be.
240 defines a tap: Tap Conductors. As used in this article, a tap conductor is defined as a conductor, other than a service conductor, that has overcurrent protection ahead of its point of supply that exceeds the value permitted for similar conductors that are protected as described elsewhere in 240.4.
To be a tap, your install would have to meet the above definition and the requirements of one of the tap rules in 240.21

Normally, if your conductors and overcurrent match, it is simply a branch circuit ot feeder.
 
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jwjrw

Senior Member
First, it will be easier for us to get rid of the Al wire and replace with #2 copper. That would remedy the 90A versus 100 A issue. The wires between the two boxes are less than 3 feet. I will do that.

Unbonding the neutral and ground are more problematic, as there are wires in the box that are going to be too short. I assume we can add a second ground bar bolted to the box and bond it to the main ground lug with some #6 for good measure. If that is acceptable, then I might be able to unbond the neutral and gound.....

Otherwise, it gets messy, with lots of external boxes to splice on longer pieces of wire to avoid splices in the panel box.

Finally, I still am curious how a second panel is supposed to be wired under tap through rules (and I accept that you are telling me is NOT our situation). But I'd still like to understand it -- are neutral and gound bonded in the box in a tap through install or not? Seems like they would be.

Adding a ground bar is fine. Why would having the connections to extend the wires inside the panel enclosure be a problem.
And if you are seperating the grounds unless Im missing something it would not have to bond the ground bar.
 

augie47

Moderator
Staff member
Location
Tennessee
cdherman, while we appreciate your visiting the forum, as you are aware it is designed primarily for individuals connected directly to electrical installations. I, as all the other posters, wish to assist in solving your problems, but, since your comment in post #14 of "I will do that", it seems this is work you are performing yourself. Due to the many variables involved in any installation, as you know, we strongly advise professional electricians be involved in any repair or installation.
After discussion with other moderators, we feel it best to close this thread and I am doing so.
 
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