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NEMA OS 4 boxes

M

Mike

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2021 IECC R402.4.6 specifies NEMA OS 4 boxes when boxes are installed in the building thermal envelope, Table R402.4.1.1 for electrical /phone boxes in exterior walls can be standard boxes if an air barrier is installed behind the boxes. My question is what about boxes installed in the ceiling with attic space above, Table R402.4.1.1 only deals with recess lighting, would only NEMA OS 4 boxes be permitted in a ceiling with attic space above? thanks for any help.
 
Like this for surface mounted lights? It's what I'm using. Along with single and double gang. They are hard to source - no supplier around here has them. One said he might be able to order the Carlon version. Not cheap.

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Mike said:
Table R402.4.1.1 for electrical /phone boxes in exterior walls can be standard boxes if an air barrier is installed behind the boxes.
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This gimmie doesn't actually exist, there is a "conflict" between what the table says and what the code section requires....
 
Steveray this is a recent article in the NJ construction communicator our DCA puts out, I copied the article in reference to the boxes

communication is Key for Air Leakage and Electrical Outlet Boxes, so the title is a play-on-words I want to discuss regarding the air leakage requirement of the International Energy Conservation, Residential provisions (IECC-R) and Chapter 11 of the International Residential Boxes Okay). For the 2021 edition of these codes, a new section was added, R402.4.6 (N1102.4.6), Electrical and communication outlet boxes [air-sealed boxes]. So now you can see the play-on-words here…not my best, but you get it. Here is the full section for reference: R402.4.6 (N1102.4.6) Electrical and communication outlet boxes (air-sealed box outlet boxes and communication outlet boxes installed in the building thermal envelope shall be sealed to limit air leakage between conditioned and unconditioned spaces. Electrical and communication outlet boxes shall be tested in accordance with NEMA OS 4, Requirements for Air-Sealed Boxes for Electrical and Communication Applications, and shall have an air leakage rate of not greater than 2.0 cubic feet per minute (0.944 L/s) at a pressure differential of 1.57 psf (75 Pa). Electrical and communication outlet boxes shall be marked “NEMA OS 4 ”or “OS 4” in accordance with NEMA OS 4. Electrical and communication outlet boxes shall be installed per the manufacturer's instructions and with any supplied components required to achieve compliance with NEMA OS 4. When you look at this section alone, it appears harmless. However, take a look at Table R402.4.1.1 (N1102.4.1.1.), Air Barrier, Air Sealing and Insulation Installation, and see the following “component” and “air barrier criteria”:(Continued on next page)Page 12 ------------------------------------------------Construction Code Communicator(Communication is Key for Air Leakage and Electrical Outlet Boxes)Component: Electrical/phone box on exterior walls; Air Barrier Criteria: The air barrier shall be installed behind electrical and communication boxes. Alternatively, air-sealed boxes shall be installed. At first glance, looks like they are conflicting. So, I asked the International Code Council. They condensed my inquiry down to a single sentence (we all know I’m long winded) and answered as such: Q: Does the testing requirement for electrical and communication outlet boxes in Section R402.4.6 supersede the Electrical/phone box on exterior walls provision of Table R402.4.1.1?A: No, Section R402.4.1.1 and Section R402.4.6 require that outlet boxes located in the building thermal envelope to be tested in accordance with NEMA OS 4 when they penetrate the air barrier in the building thermal envelope. Table R402.4.1.1 offers two options for the installation of outlets at the building thermal envelope. The first option is to install the air barrier behind the electrical and communication boxes. In this instance the box would not penetrate the air barrier and the tested and labeled boxes would not be required. The second option is to provide air-sealed boxes when they penetrate the air barrier. When the second option is selected, the use of NEMA OS 4 tested and labeled boxes in accordance with Section R402.4.6 is required. Source: Rob Austin Code Assistance/Development Unit (609) 984-7609
 
Mike said:
Steveray this is a recent article in the NJ construction communicator our DCA puts out, I copied the article in reference to the boxes

communication is Key for Air Leakage and Electrical Outlet Boxes, so the title is a play-on-words I want to discuss regarding the air leakage requirement of the International Energy Conservation, Residential provisions (IECC-R) and Chapter 11 of the International Residential Boxes Okay). For the 2021 edition of these codes, a new section was added, R402.4.6 (N1102.4.6), Electrical and communication outlet boxes [air-sealed boxes]. So now you can see the play-on-words here…not my best, but you get it. Here is the full section for reference: R402.4.6 (N1102.4.6) Electrical and communication outlet boxes (air-sealed box outlet boxes and communication outlet boxes installed in the building thermal envelope shall be sealed to limit air leakage between conditioned and unconditioned spaces. Electrical and communication outlet boxes shall be tested in accordance with NEMA OS 4, Requirements for Air-Sealed Boxes for Electrical and Communication Applications, and shall have an air leakage rate of not greater than 2.0 cubic feet per minute (0.944 L/s) at a pressure differential of 1.57 psf (75 Pa). Electrical and communication outlet boxes shall be marked “NEMA OS 4 ”or “OS 4” in accordance with NEMA OS 4. Electrical and communication outlet boxes shall be installed per the manufacturer's instructions and with any supplied components required to achieve compliance with NEMA OS 4. When you look at this section alone, it appears harmless. However, take a look at Table R402.4.1.1 (N1102.4.1.1.), Air Barrier, Air Sealing and Insulation Installation, and see the following “component” and “air barrier criteria”:(Continued on next page)Page 12 ------------------------------------------------Construction Code Communicator(Communication is Key for Air Leakage and Electrical Outlet Boxes)Component: Electrical/phone box on exterior walls; Air Barrier Criteria: The air barrier shall be installed behind electrical and communication boxes. Alternatively, air-sealed boxes shall be installed. At first glance, looks like they are conflicting. So, I asked the International Code Council. They condensed my inquiry down to a single sentence (we all know I’m long winded) and answered as such: Q: Does the testing requirement for electrical and communication outlet boxes in Section R402.4.6 supersede the Electrical/phone box on exterior walls provision of Table R402.4.1.1?A: No, Section R402.4.1.1 and Section R402.4.6 require that outlet boxes located in the building thermal envelope to be tested in accordance with NEMA OS 4 when they penetrate the air barrier in the building thermal envelope. Table R402.4.1.1 offers two options for the installation of outlets at the building thermal envelope. The first option is to install the air barrier behind the electrical and communication boxes. In this instance the box would not penetrate the air barrier and the tested and labeled boxes would not be required. The second option is to provide air-sealed boxes when they penetrate the air barrier. When the second option is selected, the use of NEMA OS 4 tested and labeled boxes in accordance with Section R402.4.6 is required. Source: Rob Austin Code Assistance/Development Unit (609) 984-7609
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Thanks Mike, but maybe they should have written the code to say "electrical boxes that penetrate the air barrier shall be marked NEMA OS4" not boxes that penetrate the thermal barrier...
 
Steveray, I agree, what makes it more confusing in NJ the electrical inspector enforces only the boxes and the building inspector enforces the table, as an electrical inspector I do not deal with air barriers for inspections, so I have been asking on plan review to make clear on the plans air barrier per the table or NEMA OS 4 boxes
 
Mike said:
Steveray, I agree, what makes it more confusing in NJ the electrical inspector enforces only the boxes and the building inspector enforces the table, as an electrical inspector I do not deal with air barriers for inspections, so I have been asking on plan review to make clear on the plans air barrier per the table or NEMA OS 4 boxes
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And this is the reason we are trying to pump the brakes with the energy code folks....They are writing bad code...
 
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