Waterproofing, Water Resistance and the NEC

Chuck Planek, President of Home Engineers Inc, recently asked us to write on waterproofing and water resistance, and their meanings as defined by the NEC.

What exactly is the NEC (National Electrical Code)?

Note that the NEC isn’t a law in and of itself. It’s a series of articles detailing recommended practices concerning electrical wiring and installations. If your local municipality or state government has adopted the NEC, then following its recommended practices would be necessary in order to get inspection approval.

If your local authorities have adopted the NEC (and many have) you should find out which version they’re using. The link above is for the 2011 version. A new one is due very soon and there are several older ones still available.

Also note that the local authorities can modify the rules of the NEC as they see fit. They can choose to change and/or ignore sections and modify the recommended practices as they see fit. If they do this, it’s in your best interest not to smack them upside the head with the printed NEC and say, “Hey, Mr. Inspector Dude. Dis ain’t what it says in the book”.

Remember at all times, the final arbiter of the NEC’s implementation is the local inspector and related authorities, even if what they say doesn’t agree with what’s in the NEC.

For your reference, a copy of the NEC can be found online here.

So what’s the deal with the NEC and weatherproof/resistant wiring?

We spent some time going through sections of the NEC to address some of Chuck’s queries. We found several sections that address outdoor wiring, low voltage systems, etc. They’re primarily Sections 520, 640 and the 800 series of articles. There are most likely others, but these stand out as being relevant to the CI market including control and A/V distribution. It would be a good thing for you to read them and find out what’s recommended for the types of systems you install.

Throughout the NEC the primary recurring messages seem to be:

  • Don’t let any wires touch other wires or materials that can damage or short circuit them
  • Use the proper sized and type of wire for the job (including wires rated for burial and in-wall installation)
  • Use conduit (and the right type of conduit) whenever possible
  • Be sure to properly ground anything that should be grounded, including conductive conduit

The NEC doesn’t define what makes a connector or other device waterproof or weather resistant. It just says when you use such products (as rated by their respective manufacturers) they should be wired properly so as not to be susceptible to shorts or ground faults, or any other potential dangerous situation. And they should be wired using cables and other devices that are rated to the same level of weather resistance as the item being installed.

 The NEC also recommends surge protection for devices wired to the outdoors, like outdoor speakers. You can click below for a refresher on the Panamax MOD-SPKR.

Panamax outdoor wiring surge suppressor

Here’s a few other tidbits:

  • The NEC defines weatherproof: Weatherproof: Constructed or protected so that exposure to the weather will not interfere with successful operation.
  • Informational note: Rainproof, rain tight, or water tight equipment can fulfill the requirements for weatherproof where varying weather conditions other than wetness such as snow, ice, dust, or temperature extremes, are not a factor.

Also note that every Terra speaker with our burial-grade “pigtail” comes with our silicone-filled, direct burial rated quick wiring connector that’s set up for daisy chaining if necessary.

Questions? Contact us at 207-725-1005 or you can e-mail us at info@terraspeakers.com.