An electrical plug for an associated electrical device for use in hazardous locations, comprising a metal housing; a nonconductive plug base holding at least two conductive terminal prongs connected to conductor wires passing through the housing and connected at their other end to the electrical device; and a plastic sleeve for preventing contact between the conductor wires and the metal housing, providing a bearing surface for the plug base and an elastomeric gasket compressed therebetween, cooperating with a reversible clamp to mechanically grip the conductor wires and prevent their separation from the terminal prongs, and providing simple measurement of a predetermined length of wire between the clamp and each terminal. A rubber grommet provides a moisture-resistant seal along the back end of the plug housing. A label plate may be affixed to the exterior surface of the plug housing by means of peened over posts that do not interfere with the integrity of the plug housing.