A lightning protection system for a wind turbine blade (22, 170) with a blade wall (22a, 174, 178) and a blade cavity, the lightning protection system comprising: a socket configured to extend at least partly through the blade wall, the socket including a socket body, a plurality of first teeth arranged in a first circumferential array, and a first retention shoulder; a receptor plug configured to be secured to the socket with the receptor plug disposed at least partly within the blade cavity, the receptor plug including a plug body, a plug conductor (76, 78, 82, 84) at least partly enclosed by the plug body, a plurality of second teeth arranged in a second circumferential array, and a retention tab extending away from the plug body, the retention tab including a second retention shoulder and the plurality of second teeth; the plurality of first teeth engaging the plurality of second teeth, when the receptor plug is secured to the socket, to resist rotation of the receptor plug relative to the socket; and the second retention shoulder engaging the first retention shoulder to secure the receptor plug to the socket; wherein: the first retention shoulder is part of a plurality of discrete first retention shoulders disposed at least partly within a central opening of the socket body; the retention tab is part of a plurality of discrete retention tabs; the second retention shoulder is part of a plurality of discrete second retention shoulders included on the plurality of discrete retention tabs; and the plurality of discrete second retention shoulders engage the plurality of discrete first retention shoulders to secure the receptor plug to the socket. a socket configured to extend at least partly through the blade wall, the socket including a socket body, a plurality of first teeth arranged in a first circumferential array, and a first retention shoulder; a receptor plug configured to be secured to the socket with the receptor plug disposed at least partly within the blade cavity, the receptor plug including a plug body, a plug conductor (76, 78, 82, 84) at least partly enclosed by the plug body, a plurality of second teeth arranged in a second circumferential array, and a retention tab extending away from the plug body, the retention tab including a second retention shoulder and the plurality of second teeth; the plurality of first teeth engaging the plurality of second teeth, when the receptor plug is secured to the socket, to resist rotation of the receptor plug relative to the socket; and the second retention shoulder engaging the first retention shoulder to secure the receptor plug to the socket; wherein: the first retention shoulder is part of a plurality of discrete first retention shoulders disposed at least partly within a central opening of the socket body; the retention tab is part of a plurality of discrete retention tabs; the second retention shoulder is part of a plurality of discrete second retention shoulders included on the plurality of discrete retention tabs; and the plurality of discrete second retention shoulders engage the plurality of discrete first retention shoulders to secure the receptor plug to the socket. the first retention shoulder is part of a plurality of discrete first retention shoulders disposed at least partly within a central opening of the socket body; the retention tab is part of a plurality of discrete retention tabs; the second retention shoulder is part of a plurality of discrete second retention shoulders included on the plurality of discrete retention tabs; and the plurality of discrete second retention shoulders engage the plurality of discrete first retention shoulders to secure the receptor plug to the socket.