NEMA 12 enclosure with drilled and tapped holes using bolts threaded from outside to hold parts inside the enclosure do I need to gasket the bolt heads with NEMA gasket material or o-rings?
A NEMA 12 enclosure will be intended for indoor use to provide a degree of protection to personnel against access to hazardous parts and to provide a degree of protection to the housed equipment against ingress of solid foreign particles. It will also provide protection to its contents against the dripping or light splashing of water. This is roughly translates to the IP54 rating that would be used in Europe.
As such, I would always suggest that any intrusion into the enclosure should be appropriately sealed if the original rating of the enclosure is to be maintained. It would therefore be advisable to install NEMA gaskets or o-rings around the bolts to ensure protection to the required level.
There would be no value in specifying gaskets or o-rings with a higher NEMA rating than the original enclosure as the protection of the enclosure cannot be increased through ‘over sealing’.
If you need any additional information, please feel free to email me firstname.lastname@example.org