My home builder gave me cat5e outlets in the wall (near the ceiling, for cameras) with just a plain white wall plate. Behind the wall plate is an open back wall box (I think), the cat5e cable and a whole lot of insulation (the pink puff balls kind that go between walls to retain heat). I replaced the wall plate with this https://www.amazon.com/gp/product/B00DL93SLU

I heard somewhere that all holes in the wall with wires/plumbing coming out should be closed with fire insulation foam. Should I get some fire foam and seal it up? Or should I replace the open back wall plate with a close box? Or do I replace the wall plate I have and install an ethernet interface?


For mains electrical power, you need fully enclosed boxes, to reduce chance of fires from electrical arcing.

You don't need that for low voltage wiring. An open back box or "wish box" is just fine. Weirdly, I priced the two types of box yesterday, and the "wish box" was 40% more expensive.

Do not under any circumstances fill any electrical junction box with foam.
You weren't saying you would, but somebody is going to read this and maybe think that. Anyway, most foams are fire accelerants not retarders, and it is easy for even professionals to make Very Big Mistakes in this area.

I don't like the starburst shape "gasket" either. I would install a listed wall plate receptacle so you have a proper Ethernet socket in your wall. A listed receptacle will be tested for fire safety. Amazon tends to be glutted with Cheese junk and counterfeits, so watch out.

  • I live in a multi unit building. Don't I need foam to ensure fire doesn't spread because of draft from this hole? – user71123 Jun 21 '17 at 6:31
  • I've never heard of foam being used as a fire deterrent and I've never heard of that as a code requirement. I have heard of foam being used as a fire accelerant. It sounds like you might've just dreamed that one up... OR... it's a local requirement of your local AHJ due to local conditions (AHJ=Authority Having Jurisdiction, i.e. your city or county electrical inspector). In which case they will have a very particular foam in mind (random foam products will not cut it.) – Harper Jun 21 '17 at 14:47
  • There is a foam used for fire stopping, colored orange and used for drilled holes for wires and pipes. – Jack Jun 21 '17 at 14:49
  • I certainly didn't dream it up. In fact, my local home depot has three grades. – user71123 Jun 21 '17 at 15:20
  • The fact that local Big-Box sells it means less than nothing, though. They cheerfully sell you all sorts of things that violate code, SMH... Honestly if you live in a multi-unit building then a) you're urban enough to have an active, staffed AHJ, and b) your building will have management who defines best practices for the facility. So that is two resources this question should go to. – Harper Jun 21 '17 at 17:03

Cat 5 is considered a low voltage wire and does not require a closed back box. I've done this a ton and used the Carlon orange every time, insulation or not.

I wouldn't use that star plate. Most places sell quickport plates that a Cat 5 keystone will fit into. I would use that instead. The star stuff can tear and break, not to mention looking unsightly.

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