Seal For Soundproofing Outlet & Light Boxes

Seal For Soundproofing Outlet & Light Boxes

The Electric Box Seal is a specially molded fire resistant neoprene seal for outlet boxes. It is a gasket that fills the gaps between the cover plate (not included) and the wall surface to seal a common weak point in sound and air flow and significantly improves the STC performance of the outlet and recepticle.

Color: Supplied in beige and available in many standard designs. Select from options below.

*Important Note Regarding Duplex Designs: Designs marked with an * are NOT compatible with Cooper Wall Plates. They will fit all other standardized NEMA devices. For Cooper Duplex Receptacles an alternate design can be purchased through our office. A minimum purchase will be required.

Price: $4.24
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The Electric and Light Switch seal is a pre formed acoustical and air seal for outlet boxes made of specially-molded fire resistant neoprene in similar size and configuration as a cover plate for a recessed electrical device. It is a gasket that fills the gaps between the cover plate (not included) and the wall surface and between the electrical device and the cover plate. It is held tightly against the wall surface by the cover plate. This seal is a great air seal for air leaks in outlets and recepticles.

Why a Electric Box Seal?

Partitions are tested for sound isolation under ideal laboratory conditions and are given a rating for the amount of sound they stop from passing through called the Sound Transmission Classification (STC). Recessed outlets are essentially holes in the wall that let sound through from one side to the other. A pair of outlets on both sides of a partition has a value of only STC-19 so they stop much less sound than the wall. Depending on the size and number of outlets in the wall, overall performance of the sound isolation separation is severely compromised.

Increasing the STC performance of the partition does nothing to improve the sound isolation overall since the sound still comes through the recessed outlets. Consider a pail of water with holes in it – increasing the thickness of the shell does nothing to keep water from pouring through the holes.

The outlets need to be sealed to obtain the performance level of the partition. Lab tests, field tests and theoretical calculations all show that the Box Seal™ improves the value for the outlet from STC-19 to STC-26, an increase that translates to significant improvement in the overall sound isolation performance of the separation. Full recovery of the partition STC value is usually achieved, given a reasonable number of outlets and normal sound absorption values in the receiving room.

This seal is particularly recommended for any partition of STC 45 or higher to maintain the best overall performance of the acoustical separation.

Benefits of Electric Box Seal

  • Matches or exceeds the performance of any acoustical sealant currently on the market as proven by independent tests.
  • Seals around the device as well as the outlet box where sealants only treat the perimeter of the box.
  • No waste, no tossing-out of half-used tubes of sealant.
  • Easier and quicker to install than sealants, with no preparation of surfaces, mess or cleanup required and significantly lower labor cost.
  • Almost limitless shelf life compared to sealants, with no temperature limitations for storage or installation.
  • No hazardous products compared to sealants, some of which irritate the respiratory tract, eyes or skin. The Box Seal™ does not contain polybutene, petroleum distillates, or airborne carcinogens.
  • Outperforms simple fiber or foam gaskets currently on the market for sound isolation.
  • Easily removed and reinstalled with the cover plate, offering access to wiring.
  • Used not only in new construction, but also as a retrofit sound control improvement for electrical outlet boxes currently in use.
  • For more information, make sure to read Why the BoxSeal is Necessary for Sound Control and Why the BoxSeal is Necessary for Fire Resistance.


This seal should be used wherever acoustical privacy and noise control are valued. It is ideal for retrofit as well as new construction.

  • Private offices
  • Conference rooms
  • Personnel offices
  • Patient rooms
  • Hotel rooms & bathrooms
  • Tenant demising partitions
  • Consultation rooms
  • Medical exam rooms
  • Classrooms
  • Auditoriums
  • Theaters
  • Teleconference rooms
  • Band rooms
  • Fabrication areas
  • Laboratories
  • Mechanical equipment rooms

Available Designs, See Data Sheet:

  • Duplex-Single*
  • Duplex Pair*
  • Toggle Switch-Single
  • Toggle Pair
  • Decora-Single (Rocker, GFCI, Motion Detector)
  • Decora Pair (Rocker, GFCI, Motion Detector)
  • Data / Phone Terminal Single
  • Data / Phone Terminal Pair
  • Duplex / Toggle*
  • Duplex / Decora*
  • Blank Single (For Juntion Boxes, etc.)**
  • Blank Double (For Junction Boxes, etc.)**
  • Custom Designs Available

All Seals fit NEMA devices and wall plates made by Cooper, Hubbell, Leviton, Lutron, Mulberry Metal, Pass & Seymour/Legrand EXCEPT Cooper wall plates for duplex receptacles.

*IMPORTANT NOTE: Seals marked by * are NOT compatible with Cooper Wall Plates. They will fit all other standardized NEMA devices. For Cooper Duplex Receptacles an alternate design can be purchased through our office. A minimum purchase will be required.

**Note, Screw holes not included in Blank Designs. Holes can be easily punched with screw or standard hole puncher.

Note, Cover Plate not included.

Physical Properties:

  • Standard Color Beige; Custom Colors Available through our office
  • Nominal Thickness:  1/16 inch
  • Shelf Life: 100 years or more.
  • Storage: Unaffected by heat, cold, humidity or other typical environmental conditions.
  • Limitations: None
  • Surface Burning (ASTM E84): Class A
  • Sound Transmission (ASTM E90): Increases STC of recessed outlets from STC-19 to STC-26.
  • Safe Handling Information: No special precautions required

Note, Available in beige and standard sizes through our website. For additional sizes and colors, contact us at 845-388-1200.

Product Data

Click to Print: Product Data Sheet

Click to View: Why the BoxSeal is Necessary for Sound Control

Click to View: Why the BoxSeal is Necessary for Fire Resistance

Available Designs

Available Designs for STC BoxSeal

Compliance Details

Available Designs for STC BoxSeal

Field Tests

Available Designs for STC BoxSeal
Installation Guide

Click to Print Installation Guide

Installation Guide for STC Box Seal for Soundproofing Outlet and Light Boxes


Verify that the edge of the outlet box is flush with or slightly recessed rom the wall surface. Remove any burrs from the cut edge of the gypsum board opening that may interfere with a smooth, tight fit to the wall.


With the electrical device installed and the wall plate removed, place the performed seal over the exposed outlet box flush with the device protruding through the precut opening in the seal.

  • The front of the Box Seal faces the wall plate and has long recesses for stiffening ribs on some manufacturer’s wall plates to fit without warping.
  • The back of the Box Seal faces into the outlet box. It has “STC Box Seal” and “Patened Pending” embossed on it, and ribs that fit into the annular space of theopening for the outlet box.

Fit the wall plate over the preformed seal and hold in place with plate-securing screws.

  • Use 1/2” long 6-32 oval head screws (some wall plates come with screws that are too short to fit into the device.)
  • For one-hour partition applications where outlets on opposite sides are less than 24-inches apart, including back-to-back, use metal wall plates with the Box Seal to comply with IBC 714.3.2 and UL 1479.  

Tighten screw to pull the device flush with the wall plate and the wall plate snugagainst the face of the gypsum board.


No maintenance is expected. The Seal may be removed to access wiring and reinstalled with the cover plate.

Shipping & Returns

Shipping and Return information is specific to this product page only (not for other products on our site).

  • Shipping:
    • This product usually ships within one business day from NY. Please call to verify stock before purchasing large quantities.
    • FREE SHIPPING on orders over $99.00. There will be a flat $14.99 shipping and handling fee on orders under $99.00. - Applies to orders shipped within the USA (excluding Alaska and Hawaii).
    • Ships via major carriers, such as UPS or FedEx Ground, with tracking information provided.
  • Returns:
    • Product can be returned up to 30 days if in brand new condition.
    • A $10.00 fee will be deducted from each return to cover our original shipping cost.
    • Please call or email us to receive an RMA number before returning. No returns will be processed without an RMA number.
    • Return shipping is customer's responsibility. A return address will be provided with RMA#.
    • If you are shipping via USPS (not recommended) do NOT require signature as we will not be able to pick up your package from local post office facility.
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Product reviews are only available to verified buyers of this product. To leave a review, please refer to the product review email we sent you.
  • Great Overall Soundproofing (2)
  • Effective (1)
  • Visually Unpleasing (1)
best uses
  • Residential party wall (1)

Reviewed by 4 customers

Displaying reviews 1-4

By mario

from los angeles

Verified buyer
Causes outlet cover to bulge out too much
  • Visually Unpleasing
best uses
Comments about Seal For Soundproofing Outlet & Light Boxes:
Hi, these gaskets are too thick and not designed well enough to fit standard outlet covers. The quick fix for this problem would be to design custom outlet covers which could easily fit the seals.

By Lio

from Palm Springs CA

Verified buyer
Great product
  • Great Overall Soundproofing
best uses
Comments about Seal For Soundproofing Outlet & Light Boxes:
Great for soundproofing and insulating electrical outlets.
Bottom Line Yes, I would recommend this to a friend

By Designer

from New Hope PA

About Me Home owner and renovator of many older homes

Verified buyer
Great product!
  • Great Overall Soundproofing
best uses
  • Residential party wall
Comments about Seal For Soundproofing Outlet & Light Boxes:
The new plastic boxes allow sound to easily travel. The outlet insert help quite a bit,
Bottom Line Yes, I would recommend this to a friend

By Float Room builder

from Rapid City, SD

Verified buyer
Worth the $
  • Effective
best uses
Comments about Seal For Soundproofing Outlet & Light Boxes:
So easy to install, these fortify one of the weak points in the wall.
Displaying reviews 1-4
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Customers Questions and Answers

1) Marina R: I'm concerned that the seal will prevent the outlet cover from contacting the wall. Is there any issue with that? Thanks

Trademark Soundproofing Reply: There is a small lip on the seal. That seals between the edge of the plate and the wall.

2) Sam: I have a box with 4 data ports. Can the blanks be used to cut out different configurations not offered?

Trademark Soundproofing Reply: Yes the blanks can cut out as you wish you will just be missing the tight seal around the ports, you will still have the outer seal.

3) Greg: can I get these outlet seals in white?

Trademark Soundproofing Reply: As of now they are only available in the cram color you see on the page (for very large orders we can have a custom run done).

4) Sally C: Are these seals for outlets and light boxes different than what is supplied by the electric company here in Cincinnati, OH? They're white and they're kind of like a foam? And are these seales bigger than the gang box for a more snug fit?

Trademark Soundproofing Reply: Not sure what is being supplied there. Ours is rubber and not foam and specially formulated and tested to seal for sound leaks. They are larger than the box and are the same size as the covers.

5) Drew: Hi There, I bought several of these and I need a triple light switch seal. Do you have a triple?

Trademark Soundproofing Reply: Hi Drew. Currently we do not have one for a triple light switch.

6) WILLIAM K: are these UL LISTED?

Trademark Soundproofing Reply: The single duplex configuration is UL-certified and listed as a wall opening protective material (R38040), and complies with IBC 714.3.2 (24-inch Rule) for 1-hour fire partitions. This is usually enough for apartments including kitchens where single duplex outlets end up back-to-back. However, the other configurations have not yet been UL tested. The product is ASTM E84 Class A fire rated.

7) Tina W: How does your pricing work? I am looking at the Duplex Single Electric Box Seal. The website price is $4.24. Is that a unit price? $4.24 for one gasket?

Trademark Soundproofing Reply: Yes that is the price per piece.

8) Dan M: Hi, I am looking at using this product in a facility in Canada. Do you guys have CSA/ULC approval? Thanks, Dan

Trademark Soundproofing Reply: Hi Dan. Yes. We have that approval. Thank you.

9) K: Hi, Before I purchase I want to make sure I am buying the right one. Is the duplex single electric box seal for a standard 2 plug wall cover? Thanks, K

Trademark Soundproofing Reply: Yes. 2 plugs one on top of the other.

10) Jessie Roy: Hello, Is any test data available for the BoxSeal product that shows it's performance compared to putty pads that wrap around recessed boxes? Thank you.

Trademark Soundproofing Reply: Hi Jessie. We do not have a head to head comparison of the 2. If the wall is open and it is possible to install putty pads, we highly recommend doing that. You can always add the box seal on as well.

11) RAMON DE O: Hi friends! I want to buy some seals for my electrical and light switches, but I can't tell what's what based on the photos. Is the "decor" switch the single wide switches?

Trademark Soundproofing Reply: Yes the "Decora Single" is for the single wide switches.

12) Ron : Hello, I was wondering if you knew if these outlet seal's worked on Eaton brand wall plates as well? Thanks

Trademark Soundproofing Reply: All wall plates fit Except the duplex receptacle versions – there is a stiffening plate that is very problematic for the design of the seal.

13) Troy: What's the difference between Duplex / Decora , Decora Single and Decora Pair ? I have newer construction with duplex (decora) square style outlets (and matching square rocker switches). Some single-gang boxes and some dual-gang. basically this: _['.']_ _['.']_ or _[roc]_ _[ker] or _['.']_['.']_ _['.']_['.']_ or _['.']_[roc]_ _['.']_[ker]_ Thanks

Trademark Soundproofing Reply: Hi Troy. If you choose any of the models from the drop down, the image will change to show you exactly the style. Currently our cut outs will not fit the square outlets. You can buy a "blank" and do the cut out on your own. Thank you.