1. ATTENTION returning members. If you are coming here from the old forum for the first time, you will need to reset you password. However, we had an email problem getting password reset links set out to a lot of the email addresses. That problem is temporarily rectified but IF you still have an issue, email me direct at info@thebuildingcodeforum.com and I will give you a temporary password.
    Dismiss Notice
  2. Welcome to the new and improved Building Code Forum. We appreciate you being here and hope that you are getting the information that you need concerning all codes of the building trades. This is a free forum to the public due to the generosity of the Sawhorses, Corporate Supporters and Supporters who have upgraded their accounts. If you would like to have improved access to the forum please upgrade to Sawhorse by clicking here: Upgrades
    Dismiss Notice

Box Fill Exercise (sharpen your skills)

Discussion in 'Electrical Codes' started by jar546, Sep 21, 2018.

Tags:
  1. jar546

    jar546 *****istrator

    Joined:
    Oct 16, 2009
    Messages:
    5,831
    Likes Received:
    281
    Alright, here we go!

    You have a 4" square metal junction box 2-1/8" deep with NO integral clamps. An 1-1/2" extension ring is added to the box.

    The box has 6 cable assemblies that terminate inside the box with the following wires:

    2- 12/2 with ground MC cables
    3- 12/2 with ground, 16/2 MC-LED cables
    1- cable assembly from Emergency Light mini-inverter

    The above is broken down as follows:

    5- 12 awg equipment grounds
    1- 18 awg equipment ground (from EL mini inverter)

    5- 12 awg neutrals

    5- 12 awg hots

    6- 16 awg LED dimmer control wires

    11- 18 awg emergency light inverter wires (12-1=11 equip gnd grouped above)

    FYI, the extension ring is not marked with cubic inch capacity.


    There are no devices in the box, just the wires, ground screw, extension ring and cover plate.

    Is there adequate space in the setup as described for box fill?
     
    #1 jar546, Sep 21, 2018
    Last edited: Sep 22, 2018
  2. RJJ

    RJJ Platinum Member

    Joined:
    Oct 17, 2009
    Messages:
    2,935
    Likes Received:
    56
  3. jar546

    jar546 *****istrator

    Joined:
    Oct 16, 2009
    Messages:
    5,831
    Likes Received:
    281
    Wow, just one taker on this one?

    No one does electrical inspections? The could easily happen in a residence too.
     
  4. ICE

    ICE Sawhorse

    Joined:
    Jun 23, 2011
    Messages:
    7,675
    Likes Received:
    671
    Can I get a picture?
     
  5. jar546

    jar546 *****istrator

    Joined:
    Oct 16, 2009
    Messages:
    5,831
    Likes Received:
    281
    No Sir. You have all the information that you need.
     
  6. Pcinspector1

    Pcinspector1 Platinum Member

    Joined:
    Oct 28, 2009
    Messages:
    2,524
    Likes Received:
    244
    If I understand the Q.

    NO, not enough room even when I buy the extension ring for your project. Need approx. 53.25 volume

    30.3 (4x2-1/8") + (22.5 RACO 1-1/2"extension ring) = 52.8 *No devises.

    Did you measure the box, if it's a 4-11/16" x 2-1/8" = (42.0) volume + ext ring 22.5 = 64.5 you'd be good
     
    jar546 likes this.
  7. jar546

    jar546 *****istrator

    Joined:
    Oct 16, 2009
    Messages:
    5,831
    Likes Received:
    281
    No sir, it is a 4" square box, not a 4-11/16" but if that were the case we would be good.

    So here is the question, RACO does list that extension ring as 22.5 BUT it is not embossed on the ring itself, therefore you have to take the same cubic inches as listed for a box that size which is 21. I think you are off a little on you calculation for what you do need. Actually, you are off a little on that........
     
  8. Pcinspector1

    Pcinspector1 Platinum Member

    Joined:
    Oct 28, 2009
    Messages:
    2,524
    Likes Received:
    244
    Jar, from the response, the inspection of boxes must not be a high priority or its not an issue until the inspector see's some abnormal amount of wiring in a box. Calculating the components is far more complicated than I thought and appreciate the exercise you posted. I diffidently wouldn't go to court with my calcs!

    According to EC&M, there is 1) Conductor volume, 2) Cable clamp Volume, 3)Support fitting volume, 4) Device yoke volume and 5) Equipment-grounding conductor volume that has to be calculated.

    And then the box and ring allowable volume.

    I'd be curious how other inspectors are alerted to box overfill, like when you see several conduits entering a box, like 4,5 or 6 conduits, do you start to have convolutions and drop your coffee cup?
     
    jar546 likes this.

Share This Page