Article 314, JB fill calculation with DIN rail devices

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lukefeil

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Lake Orion, Michigan
Hello Everyone,

How do you calculate JB fill (Article 314) for a JB that contains a DIN rail with equipment? 314.16(B)(4) has only provisions for strip or yoke mounted equipment?

  • The JB is a Cooper 864 SC, 8x64 = 192in³
  • The wiring I have to count, for now I got:
    • The main conductors are 9x #6 = 45in³ (Table 314.16(B))
    • Then control wiring 14x #14 = 28in³

How do I account for the PDB and terminals?

IMG_20190121_142006246 (Small).jpg

Best regards,
Lukas
 
Interesting question, is there anything in Article 314 for a calculation for anything other than conductors?
 
No, even 314.28(E)(2) does not provide information on fill calculation, only a calculation for the minimum size of box (a very confusing one...)

On the other hand, does 314.28(E) indicate that the terminal blocks are not allowed in the JB?
 
Although the enclosure appears to be a typical screw cover junction box maybe this could actually be an industrial control which would fall under 409.104(A).

409.104 Wiring Space.
(A) General. Industrial control panel enclosures shall not
be used as junction boxes, auxiliary gutters, or raceways for
conductors feeding through or tapping off to other switches or
overcurrent devices or other equipment, unless the conductors
fill less than 40 percent of the cross-sectional area of the wir-
ing space. In addition, the conductors, splices, and taps shall
not fill the wiring space at any cross section to more than
75 percent of the cross-sectional area of that space.
Click to expand...
 
This box would be subject to the provisions of article 312 cabinets in this case, not the provisions of the junction box. So you have the deflection requirements and the wireway fill requirements of that section, unless you have wires that travel through the box spliced or unspliced, in that case you would have to comply with the diameters of pull boxes, but i don't believe you have a fill issue. I think they don't assume you would and your picture certainly isn't going to have enough conductors to be "full" in the 314 sense.
 
The only thing I could find was 312.8 but it really doesn't apply but you could use it as a guideline.

312.8 Switch and Overcurrent Device Enclosures. The wiring
space within enclosures for switches and overcurrent devices
shall be permitted for other wiring and equipment subject to
limitations for specific equipment as provided in (A) and (B).
(A) Splices, Taps, and Feed-Through Conductors. The wiring
space of enclosures for switches or overcurrent devices shall be
permitted for conductors feeding through, spliced, or tapping
off to other enclosures, switches, or overcurrent devices where
all of the following conditions are met:
(1) The total of all conductors installed at any cross section of
the wiring space does not exceed 40 percent of the crosssectional
area of that space.
(2) The total area of all conductors, splices, and taps installed
at any cross section of the wiring space does not exceed
75 percent of the cross-sectional area of that space.
(3) A warning label complying with 110.21(B) is applied to
the enclosure that identifies the closest disconnecting
means for any feed-through conductors.
Click to expand...
 
lukefeil said:
No, the documentation shows that this enclosure is Listed as a junction box...
Click to expand...

What documentation, a the label applied when they made the box or after they built this control panel? Is there a reason why a box cannot be used to create something like a control panel as long as it marked according to 409.110.
 
infinity said:
What documentation, a the label applied when they made the box or after they built this control panel? Is there a reason why a box cannot be used to create something like a control panel as long as it marked according to 409.110.
Click to expand...

listed boxes are general what is used to house industrial control panels.

I am not sure this would qualify as an ICP though.

Industrial Control Panel. An assembly of two or more components
consisting of one of the following: (1) power circuit
components only, such as motor controllers, overload relays,
fused disconnect switches, and circuit breakers; (2) control
circuit components only, such as push buttons, pilot lights,
selector switches, timers, switches, and control relays; (3) a
combination of power and control circuit components. These
components, with associated wiring and terminals, are mounted
on, or contained within, an enclosure or mounted on a
subpanel.
The industrial control panel does not include the controlled
equipment.
Click to expand...
 
lukefeil said:
No, the documentation shows that this enclosure is Listed as a junction box...
Click to expand...

I just went through this for myself. A junction box is a cabinet or a cutout depending on its construction. Don't know why your box is listed, because indoor metal junction boxes don't need to be. The provision of article 409 DO apply. All you have to do is look up the definition of an industrial control cabinet in article 100 along with that article 312 applies.
 
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