Fire Rated Back Box Inserts for Fire and Acoustic Rated Walls

Yes. Tenmat Socket Box Inserts are preformed to fit the back box and push fit in seconds, with no kneading, moulding or adhesive. They fit up to 80% faster than socket putty pads and stay in place before the faceplate goes on. Swapping one for the other on site still needs the designer’s approval.

From EI30 to EI120, classified to BS EN 13501-2 and tested to BS EN 1366-3. EI120, a 2 hour rating, is achieved with plastic boxes in a 100 mm wall with 2 layers of 12.5 mm board and boxes offset by 150 mm (double 47 mm boxes need cavity insulation). Metal boxes reach up to EI90.

No significant reduction was recorded. The tested partition achieved Rw (C;Ctr) 67 dB for airborne sound insulation to BS EN ISO 140-3 and BS EN ISO 717-1, with sockets protected by the inserts. The insulative material also helps reduce air leakage through the socket, so the same insert serves as an acoustic back box solution.

Yes, both are tested. Plastic boxes must be fitted flush with the outer plasterboard. Metal back boxes can be flush or recessed: a 12.5 mm recess in a 100 mm wall achieves EI90, and a nominal 20 mm recess in a 190 mm twin wall achieves EI60. Check the tested configuration for your wall.

Yes, in tested configurations. Metal boxes in a 100 mm wall with 2 layers of 12.5 mm board achieve EI90 back to back. 35 mm deep plastic boxes achieve EI90 back to back when the cavity has at least 50 mm of 100 kg/m³ stone wool. Check the tested configurations or the datasheet before specifying a back to back layout.

It depends on the wall. Walls of at least 75 mm take up to 2 twin and earth 2.5 mm² cables per socket at EI30 or EI60. Walls of at least 100 mm take up to 3 at EI30 to EI120. Walls of at least 190 mm take up to 7 twin and earth 2.5 mm² cables, or 2 of 6 mm², at EI60.

Yes, subject to the tested detail. A small slit is made in the insert so it fits around the existing cables, and the slit must close back up once the cables are through. The same tested configurations and cable limits apply, which makes the insert suitable for remediation work as well as new build.

Two formats: a single insert at 70 by 70 mm and a double insert at 140 by 70 mm. Each is made in 35 mm and 47 mm depths to match standard back box depths, with a nominal thickness of 4 mm. Both are tested for metal and plastic back boxes, subject to the tested detail for your wall.

The inserts are UKCA marked under certificate 0843-CPR-1313, with UKTA 0843-UKTA-23/0021 and Declaration of Performance QA029. Classification report 4790657229-01 Issue 2 covers EI30 to EI120. Datasheet TDS 44, BIM models and NBS Source clauses are available, and the full evidence pack is sent on request for building control or Gateway 2.