SECTION 312.6 & 338.24

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PURE

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Location
columbus, ohio
Installing a standard 200amp Square D 40 space panel, entering the panel through the back knockout with a 4/0 SEU Alum. Cabinet is 3.75" deep. Inspector has failed the installation siting 312.6 for bending space. chart show 4'.

removed wiring from back and came in the top KO, meter and panel are back to back on a 2 x 8 wall.
Failed again, bending radius needs to be 10" diameter on cable. article 338.24.

I have installed services this way for 20 years and never had these calls made, any thoughts?
 

Volta

Senior Member
Location
Columbus, Ohio
I'm old school here, and our POCO didn't like us using the backs of meter cans to exit when I started, so I don't usually 'back to back' that way. Is this a slab house?

Assuming a residence full-load, you could use 2/0 cu through the nipple back to back. Only 3-1/2" needed. Assuming the panelboard enclosure is a 'cabinet'...
 

Dennis Alwon

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Chapel Hill, NC
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Article 338.24 is for the cable itself not the conductors in the cabinet. This inspector may be correct. If you came in the back at the top and the terminals are at the top I can see the problem but if you come in the back on the bottom of the panel and the terminals are at the top then he is off the mark-- 4" between the terminal and opposite wall is needed. Likewise 7" from the lug to the top of the panel is needed if you come in the top and the terminals are on the top.
 

infinity

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Maybe someone can explain to me what 312.6 means. The note at the bottom states that "Bending space at terminals shall be measured in a straight line from the end of the lug or wire connector (in the direction that the wire leaves the terminal) to the wall, barrier, or obstruction." If the wall of the cabinet is at least the minimum distance that is given in the chart does it really matter where the cable enters the cabinet? Even with a cable that enters right next to the the lugs the conductors can be bent in a loop to enter the lugs.
 

jim dungar

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312.6 says 'wire bending space at terminals', as mentioned by infinity it does not apply any where other than when measuring in a straight line from the terminal. This section is all about being able to cram wires into terminals, it really doesn't address the bending of the actual conductors.
 

Volta

Senior Member
Location
Columbus, Ohio
No, it does. Section 312.6 says "Conductors at terminals or conductors entering or leaving cabinets . . ."

I thought that at least for Metal Wireways, while referencing Section 312, there was an exception when leaving opposite a removable cover, but that might not help here. Not with careful and precise reading, anyway.
 
I believe the answer you are looking for is Code Cycle 2008 314.28(A) (2) Exception. Which states: Where a raceway or cable entry is in the wall of a box or conduit body opposite a removable cover, the distance from that wall to the cover shall be permitted to comply with the distance required for one wire per terminal in table 312.6(A)
 

Dennis Alwon

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Chapel Hill, NC
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Retired Electrical Contractor
Maybe someone can explain to me what 312.6 means. The note at the bottom states that "Bending space at terminals shall be measured in a straight line from the end of the lug or wire connector (in the direction that the wire leaves the terminal) to the wall, barrier, or obstruction." If the wall of the cabinet is at least the minimum distance that is given in the chart does it really matter where the cable enters the cabinet? Even with a cable that enters right next to the the lugs the conductors can be bent in a loop to enter the lugs.

Yes because interesting enough if the conductors enter the cabinet at the top and the terminals are at the top you need more room then if the conductors enter from the side or bottom. IMO, if they enter the back of the panel at the top and the lugs are there then you will not meet the bending space in 312.6(B).
 

Dennis Alwon

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Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
I believe the answer you are looking for is Code Cycle 2008 314.28(A) (2) Exception. Which states: Where a raceway or cable entry is in the wall of a box or conduit body opposite a removable cover, the distance from that wall to the cover shall be permitted to comply with the distance required for one wire per terminal in table 312.6(A)

Very good but that is still about the distance from the lug to the opposite wall. Most residential panels will not have the required space from the terminal-- I also think that if that hole is at the top in the back there will be issues.
 

Volta

Senior Member
Location
Columbus, Ohio
I believe the answer you are looking for is Code Cycle 2008 314.28(A) (2) Exception. Which states: Where a raceway or cable entry is in the wall of a box or conduit body opposite a removable cover, the distance from that wall to the cover shall be permitted to comply with the distance required for one wire per terminal in table 312.6(A)

Thanks, that's the one.
 

infinity

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New Jersey
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Yes because interesting enough if the conductors enter the cabinet at the top and the terminals are at the top you need more room then if the conductors enter from the side or bottom. IMO, if they enter the back of the panel at the top and the lugs are there then you will not meet the bending space in 312.6(B).

OK so what part of this code wording says that?

Note: Bending space at terminals shall be measured in a straight line from the end of the lug or wire connector (in the direction that the wire leaves the terminal) to the wall, barrier, or obstruction.

And what does this mean? (A) Width of Wiring Gutters. Conductors shall not be deflected within a cabinet or cutout box unless a gutter having a width in accordance with Table 312.6(A) is provided.
 

Dennis Alwon

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Chapel Hill, NC
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I read art. 312.6(B)(2) referring to T. 312(6)(B). The note at the bottom of the table states this:

1. Bending space at terminals shall be measured in a straight line from the end of the lug or wire connector in a direction perpendicular to the enclosure wall.

This is for wires leaving or entering opposite the lugs.
 

Dennis Alwon

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Chapel Hill, NC
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from the handbook

Section 312.6(B)(2) and Table 312.6(B) provide the requirements for wire-bending space where straight-in wiring or offset (double bends) is employed at terminals. Section 312.6(B)(1) applies only to 90 degree bends. The notes to Table 312.6(B) permit a reduction in required
bending space for removable and lay-in wire terminals. The removable terminal wire connectors can be either the compression type or the setscrew type. However, connectors are required to be of the type intended for a single conductor (single barrel). Removable connectors designed for multiple wires are not permitted to have a reduction in bending space.
To facilitate wiring, a terminal may be placed on the stripped end of the conductor, which has been cut to the proper length. The terminal is crimped or lightly torqued on the wire as intended. The wire is bent and routed to facilitate mounting onto the stud or landing pad for proper connection. All mechanical screws, bolts, and nuts involved should then be torqued to the proper value. See the commentary following
the informational note to 110.14 regarding tightening torques.
In accordance with the notes to Tables 312.6(A) and 312.6(B), when Table 312.6(A) is used, bending space is measured in the direction in which the wire leaves the terminal, and when Table 312.6(B) is used, it is measured in a direction perpendicular to the enclosure wall.
A lay-in-type terminal is a pressure wire connector in which part of the connector is removable or swings away so that the stripped end of the conductor can be laid into the fixed portion of the connector. The removable or swingaway portion is then put back in place and the connector
tightened down on the conductor. Exhibit 312.1 applies the rules of 312.6(B)(1), 312.6(B) (2), and Tables 312.6(A) and 312.6(B) to the wiring for a lay-in-type terminal according to the following list, where T stands for the dimension to the terminal, and G stands for dimension of the gutter.
 

infinity

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New Jersey
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I read art. 312.6(B)(2) referring to T. 312(6)(B). The note at the bottom of the table states this:



This is for wires leaving or entering opposite the lugs.

from the handbook

But is the OP asking about the enclosure wall distance or the KO distance that he brought the cable into? Or are they the same thing in this section?
 

Dennis Alwon

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Chapel Hill, NC
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But is the OP asking about the enclosure wall distance or the KO distance that he brought the cable into? Or are they the same thing in this section?
If the enclosure wall opposite the terminals is the wall the ko is in then the distance is the same.
 

kwired

Electron manager
Location
NE Nebraska
Installing a standard 200amp Square D 40 space panel, entering the panel through the back knockout with a 4/0 SEU Alum. Cabinet is 3.75" deep. Inspector has failed the installation siting 312.6 for bending space. chart show 4'.

removed wiring from back and came in the top KO, meter and panel are back to back on a 2 x 8 wall.
Failed again, bending radius needs to be 10" diameter on cable. article 338.24.

I have installed services this way for 20 years and never had these calls made, any thoughts?

I can't recall seeing a Square D panel in the past 20 yrs that would not allow 4/0 AWG as long as you are using factory prepunched KO's. Punch your own hole right next to the lugs and not only is it a violation it is just about impossible to land the conductors in the lugs.
 

PURE

Member
Location
columbus, ohio
cabinet depth

cabinet depth

Very good but that is still about the distance from the lug to the opposite wall. Most residential panels will not have the required space from the terminal-- I also think that if that hole is at the top in the back there will be issues.

The inspector is not siting the distance to the terminal as that is 9inches.
He is siting that my panel is 3 and 3/4" deep and you need 4" to bend a peice of 4/0, stating that you can not bring 4/0 into the back of any standard 200amp panel box. Deflection only, terminals not involved.

The wire comes out of the bottom of the meter and into the back of the panel.
 

Dennis Alwon

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Location
Chapel Hill, NC
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Retired Electrical Contractor
The inspector is not siting the distance to the terminal as that is 9inches.
He is siting that my panel is 3 and 3/4" deep and you need 4" to bend a peice of 4/0, stating that you can not bring 4/0 into the back of any standard 200amp panel box. Deflection only, terminals not involved.

The wire comes out of the bottom of the meter and into the back of the panel.

Well then he is incorrect-- an lb would be no different- ask him how they are rated for 4/0 wiring.
 

elohr46

Senior Member
Location
square one
Well then he is incorrect-- an lb would be no different- ask him how they are rated for 4/0 wiring.

A 2" crouse-hinds alum. LB is rated for a maximum of three 4/0 conductors and the distance measured from the hub to the cover is 4.24" according to their website. I know, it doesn't seem right, but that's what it is. So it looks like the inspector is right.
 
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