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Discussion Starter · #1 ·
I am installing a ceiling fan and lighting under a new outdoor patio cover. The lights and fan are damp-rated. I am intending on installing a single-gang combination switch/dimmer that has a dimmer for the lights and a multi-speed switch for the fan. However, I can't find one that is damp-rated for outdoor installation. I will be installing the switch in an outdoor-rated box with an "in-use" type cover and it will be under the roof cover in a location that likely will never, ever be exposed to direct liquid (rain, snow, whatever).

I know that a UL rating is a UL rating and all the responsible people here will want to tell me "NO!", but what would be the implications if I installed the "dry location"-rated switch outdoors in the "safe" location? Obviously the only concern is humidity in the air... but how is that different from someone who doesn't have central air conditioning, lives somewhere humid, and always has the windows open? The electrical engineers in my office say (off the record) that it's probably fine and that UL is probably covering their rears, and nothing more. But is there something unique in a rheostat-type dimmer switch that would react negatively to humidity? Just looking for any practical experience, if anyone here has any, with this situation. What could go wrong with this switch that wouldn't go wrong with a plain old switch or receptacle in an outdoor damp location?
 

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Scared Electrician
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In a box with an in-use cover on it is considered a dry location, so use of a standard switch/dimmer in this case would be ok. I would however recommend that it be protected by a GFI. It might be even required.
 

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Discussion Starter · #3 ·
In a box with an in-use cover on it is considered a dry location, so use of a standard switch/dimmer in this case would be ok. I would however recommend that it be protected by a GFI. It might be even required.
Thanks - I will have it GFCI-protected.

The website where I was looking at switches/dimmers had a pop-up link explaining "dry", "damp", and "wet/outdoor" per the UL ratings and the dry explanation indicated a place where there would not be humidity - not even a bathroom. That sounds to me like the outdoor "in use" cover would not be "dry". But, as I said above, what about people with no AC and open windows? The switch will have the same exposure as those.

Thanks.
 
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