What is the difference between a UL rating for dry, damp, and wet locations?

Saturday, June 30, 2018

Unless the Underwriters Laboratories “UL” label on an electrical fixture has a statement on it that the fixture is “suitable for” or “rated for” a damp or wet location, then it is only approved to be installed in a dry location. Here’s the difference in the definitions of the three categories:

Dry Location - May used in any location that is normally not exposed to dampness, but may be temporarily damp. This typically means an indoor location. Ventilation is important for dissipating any temporary dampness in a dry location, and a typical example would be a luminaire (light fixture) above a mirror at a bathroom sink.

Damp Location - May be used in sheltered outdoor locations, such as a porch or carport, that are subjected to high humidity and condensation, but not direct contact with water, rain, or snow. An exterior light fixture under a roof overhang sufficient to protect it from driving rain coming down diagonally would be a damp location.

Wet Location - Suitable for locations that receive direct contact with rain, snow, or excessive moisture, such as heavy fog or coastal ocean spray. 

    Although the damp and wet ratings are primarily for outdoor installations, the National Electrical Code (NEC 410.10D) specifies that any light fixture (luminaire) located over the footprint of a bathtub or shower, up to 8 feet above it, must be rated for a damp location, except that one that is subject to shower spray must be rated for a wet location. 

    Also, see our blog post Why is the National Electrical Code (NEC) so hard to understand and complicated?

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Here’s links to a collection of our other blog posts about ELECTRICAL WIRING:

Which house appliances need a dedicated electrical circuit?

Can a short circuit cause a high electric bill?

Can you use a light switch for a water heater disconnect? 

• When did the requirement for two 20-amp kitchen counter appliance circuits begin?

What is the maximum spacing requirement for securing NM-cable (nonmetallic-sheathed cable)?

Is it alright to just put wire nuts on the end of unused or abandoned NM-cable or wiring?

What causes copper wires to turn green or black in an electric panel?  

 Is the latest edition of the National Electrical Code (NEC) the standard used for the electrical system of new homes?

What are typical aluminum service entrance wire/cable sizes for the electrical service to a house?

Why is it unsafe to bond neutral and ground wiring at subpanels?

When was it first required that neutrals and grounds be separated (not bonded) on any panel past the main service panel? 

Should I get a lightning rod system to protect my house?

Why is a strain relief clamp necessary for the cord connection to some electric appliances?  

Does a wire nut connection need to be wrapped with electrical tape?

What is the minimum clearance of overhead electric service drop wires above a house roof?

What is three phase electric service?

What is a reliable way to tell if the electrical service is 3 phase or single phase? 

Can NM-cable (Romex®) be used to make a cord and plug to connect an appliance?

What are the requirements for NM-cables entering an electric panel box?

What is the color code for NM cable (Romex®) sheathing?

Can I remove a 240-volt range receptacle and hard-wire the range? 

Why do some wires in an electric panel have tape wrapped around them near their connections?

Why is undersize electric wiring in a house dangerous? 

Why is bundled wiring in an electric panel a defect?

What causes flickering or blinking lights in a house?

What is the voltage rating of a house electrical system? 

Why are old electrical components not always "grandfathered" as acceptable by home inspectors?

What is tinned copper wiring?

What is a conduit body or condulet? 

How can I find out the size of the electric service to a house?

What could cause an extremely high electric bill?

Can old electrical wiring go bad inside a wall? 

What are the code requirements for NM-cable (nonmetallic-sheathed cable or Romex®) in an attic? 

What is the difference between "grounded" and "grounding" electrical conductors? 

What does it mean when a wire is "overstripped" at a circuit breaker?

What is an open electrical splice?

What are the most common electrical defects found in a home inspection? 

What is the life expectancy of electrical wiring in a house? 

Do any pre-1960 houses have aluminum wiring?

What is the gooey stuff on some of the wire connections in the electric panel? 

How much does it cost to rewire a house?  

What is an "open junction box"? 

What are the clearance requirements for an overhead electric service drop that is directly over or near a swimming pool? 

How dangerous is old electrical wiring? 

What is a ground wire? 

What are the most common homeowner electrical wiring mistakes?

I heard that aluminum wiring is bad. How do you check for aluminum wiring? 

What is "knob and tube" wiring? 

    Visit our ELECTRICAL page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.

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