vpritchard
Member
- Location
- Binghamton, NY
Electrical outlet boxes are stamped with the volume inside, in cubic inches. The NEC provides us with a method of calculating box fill (314.16). Conductors, loops, splices, clamps, yokes... there is an allowance made for actual wires as well as physical items in the box that do take up space...... how about firestop insert pads? Technically they consume space within the box. Hilti and a few other companies make these. I think the intent was if you have to firestop after walls have been closed, there is this wonderful product that you can stick INSIDE the box. But it takes up physical space, and would reduce the available volume for calculating fill. The very helpful technical engineers at Hilti have sent me all kinds of paperwork regarding UL testing and approvals for the "system" of having this pad inside an electrical outlet box. But they had no real answer for me when I mentioned allowances for box fill. I could imagine a scenario where an electrical inspector comes across an outlet box at max fill...lets say a 4-11/16" x 2-1/8" square box (42cu in) with 18 'conductors' in it plus one of these pads, and issues a violation. Although no one I have asked has comes across (or even thought of) this issue. To me it seems very plausible. I was curious to know if anyone has encountered this scenario and/or had any input on the topic.