Understanding Article 550.15 (H) Exception of the National Electrical Code (NEC)

Understanding Article 550.15 (H) Exception of the National Electrical Code (NEC)

The rules for protecting wiring under mobile homes that are exposed to the weather have changed over the last few years. Here’s a simple summary of what’s been going on:

  1. Code Changes: The rules, or “code,” have been updated in the last three code revisions. These updates aim to make sure that the wiring under mobile homes is safely protected from weather and physical damage.

  2. Role of Code Panels: The people who decide on these changes (code panels) don’t actually write the new rules. Instead, they review suggestions from the public and vote to accept or reject them. The person suggesting the change has to make sure it fits the style and format of the National Electrical Code (NEC®).

  3. Old vs. New Requirements:

    • 2014 Code: The rule said that any wiring under a mobile home exposed to moisture or damage had to be protected by a special pipe or tube (conduit or raceway) approved for use in wet areas.
    • 2017 Code: The rule was clarified. Now, the pipe or tube must be specifically identified for use in wet areas, not just approved. This means you can’t use just anything, like a garden hose, to protect the wiring. It must be something designed for that purpose.
     
  4. Why the Change: The old wording was confusing and didn’t make sense in parts. The new wording makes it clear that the protection must be appropriate for wet conditions and physical damage.

  5. Where to Find More Info: You can check out the full text of the code for free on the NFPA.ORG website. Look for the 2017 NEC® edition of NFPA 70.

2014 Rule:

  • Wiring exposed to weather or damage under mobile homes must be in a conduit or raceway approved for wet areas.

2017 Rule:

  • Wiring exposed to weather under mobile homes must be in a conduit or raceway specifically identified for wet areas.

This change ensures better protection and clarity in the rules.

 

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