Enclosures with grommetless strain relief are provided, each including a base and a cover. The base has a bottom and four sidewalls arranged to provide an open box-like structure. A first of the sidewalls of the base is configured with a wire routing slot at its perimeter. The cover has a top and four sidewalls arranged to provide an open box-like structure configured to couple with the base, so as to provide a strain relief for an electrical wire passing through the wire routing slot. The wire is pressed against a length of the first sidewall of the base by a first sidewall of the cover. The enclosure may include other features, such as rounded edges in the wire routing path, a wire guide and/or strap to inhibit wire movement between the first sidewalls, and/or one or more locking mechanisms configured to secure the cover to the base.