Does the National Electrical Code weigh in on the subject of metallic versus nonmetallic in-use covers for outdoor outlets attached to a single family home? I've got an up-to-date copy of "Wiring Simplified" (based on the 2017 NEC) and can't find this topic addressed.

I have no electrical outlets on the exterior of my 1942 Cape Cod. I'm planning to hire an electrician to install three outlets. The plastic in-use covers are easy to find online and in stores but the metal ones are not so common. I can buy them on Amazon (made in USA by Greenfield) but before I pull the trigger I'd like to know whether there's some code-related or other practical reason to go for the plastic ones? Yes, the plastic ones are transparent, so you can see into them. But why do I care? If I'm using them I know what's in there -- a plug. And if I'm not using them I also know what's in there -- nothing. What am I missing here?

I've seen many of the plastic ones on buildings that are broken or seem discolored or just weathered. The plain white metal of the Greenfield covers appeals to me aesthetically and I'll never have to replace them. But if an electrician refuses to install them because they're not code compliant then there's no sense in buying them. I live in Wisconsin, by the way, in case that matters.


The national electrical code only specifies extra duty or in use covers. Both plastic and diecast meet this requirement. I will not use the plastic ones as they are worse than no cover in most cases as they are always broken when I see them. Just my opinion but the few extra dollars for a diecast metal cover will last for years where the plastic ones are junk in my opinion.

  • Ed: Thanks for your help. I see from your profile you are a person who knows a thing or two about this stuff. I suspected it didn't make a difference code wise but I'm a cautious guy. Metal boxes it is. – peterreb Aug 24 '18 at 14:52

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