CTA: Line can enter Top or Bottom - Load exit Bottom (can be configured reverse). CTMS-O: Line enter Top - Load exit Bottom. CTMS-U: Line enter Bottom - Load exit Bottom. BFCTMS: Line enter Bottom - Load exit Top. CTSS - CT Cabinet and Switch are in separate enclosures which mount together (wired together in field by contractor). Can be configured for either underground or overhead service conductors.