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I've seen varying definitions of "type 1" enclosure, and most of them are informal. I've also heard it informally explained that I should be able to drop a screw into the top of the unit and not have it contact any live parts, but that's also informal. Is there a defined series of tests I can perform to claim type 1?

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    \$\begingroup\$ There's also "IP" (ingress/international protection) ratings, IP20 is somewhat common for "finger-safe" equipment, IP40 is a bit more enclosed (i.e. your screw wouldn't get in), on up to IP67 which is protected against dust and water. \$\endgroup\$ – Nick T Jul 22 '15 at 21:25
  • \$\begingroup\$ I think the ratings @NickT mentions are a lot more common. I for one have not yet stumbled upon a NEMA enclosure rating, but had conversations about IP codes with non technical people. They are also a bit more specific in their descriptions. \$\endgroup\$ – Magic Smoke Jul 22 '15 at 21:48
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Well, you can also call it a banana type 1 enclosure then or whatever else you want, because the name is rather meaningless, if it is not bound to a specification.

I guess you are referring to the NEMA enclosure types, which states type 1 to be

General-purpose. Protects against dust, light, and indirect splashing but is not dust-tight; primarily prevents contact with live parts; used indoors and under normal atmospheric conditions.

NEMA Enclosure Types is a pdf file that includes:

The purpose of this document is to provi de general information on the definitions of NEMA Enclosure Types to architects, engi neers, installers, inspectors and other interested parties. [For more detailed and complete information, NEMA Standards Publication 250-2003, “Enclosures for Electrical Equipment (1000 Volts Maximum)” should be consulted. This Standards Publication as well as all otherNEMA publications are available from IHS @ 800 854-7179 or http://www.global.ihs.com ]

The included TABLE 2 includes that type one "Provides a Degree of Protectiona gainst the Following Conditions":

  1. Access to hazardous parts
  2. Ingress of solid foreign objects (falling dirt)

But as the document says, you should consult the standard specifying document.

NEMA 250 and NEMA ICS 6 are commercially available. If you are a company/business and you want to sell products compliant to this specification, you should buy these specifications in order to do so. There is little to no point in buying these specifications as a private person. If you are just a curious private person, you should check your national/country/state library. chances are they do have these specifications available and you can read them.

If you are a student, ask your univerity or univerity library. They should have a copy of the specification available for you to read.

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In this context, enclosure type seems to be a NEMA thing. There are many types listed in that document, here is a small sample for completeness.

Type 1 Enclosures constructed for indoor use to provide a degree of protection to personnel against access to hazardous parts and to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt).

Type 2 Enclosures constructed for indoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt); and to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (dripping and light splashing).

Type 3 Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt and windblown dust); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow); and that will be undamaged by the external formation of ice on the enclosure.

As to the tests required to claim the enclosure is Type 1, it appears that those documents are behind a door you must pay to open...

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  • \$\begingroup\$ That's the kind of informality that's causing me trouble, though. "A degree of protection" could mean anything. For example, one enclosure I have has giant vent holes big enough for a quarter-inch screw. But it's still "a degree of protection", because larger things can't enter. Surely claiming that to be type 1 would be problematic. \$\endgroup\$ – Stephen Collings Jul 22 '15 at 19:58
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    \$\begingroup\$ @StephenCollings Your best bet is to pay for the standards. \$\endgroup\$ – Matt Young Jul 22 '15 at 20:00
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The NEMA 250-2003 standard(sorry, no better link..) is defining the types and tests for the applicable criterions.

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