Abstract: An electrical power connector for use in a hazardous environment, such as in a sub-sea distribution system for distributing electrical power to remote oil well heads from a marine platform. The sub-sea connector comprises first and second connector bodies, one of which houses a solid state electrical power switch and switch control means. The switch control means is responsive to a non-electrical control system, e.g. an optical signal, which is transmitted between the connector bodies by a transmission path which is interrupted when the bodies move apart by a first short distance, to cause the solid state switch to switch the power off. The actual power contacts in the first and second bodies do not separate from physical engagement until the bodies move apart by a second distance, greater than the first distance. Thus the power contacts can only separate, and engage, when they are electrically dead.