An A319 ground power plug-in panel lens cap and bulb were missing which could lead to electrical arcing so Maintenance was notified. The pilot's inspection authority was questioned.

Narrative

Upon exterior preflight I found an inoperative item which I KNEW could be MEL'd which I was fine with. I informed the mechanic at the gate about it. He said fine and then asked me why I was checking that item and the 108VU panel (panel under nose where ground electric power is plugged in). Number one; I told [the mechanic] it is part of the plane I'm responsible for. The 108VU panel is KNOWN to be conducive to moisture and with missing lens cap/light bulb; open sockets are susceptible to shorting out which I have experienced. Once; three years ago; I pushed the press to test light switch and SMOKE came pouring out of an EXPOSED socket. Who knows what THAT could have led to; perhaps a Swissair 111 accident or TWA 800 accident? I prevented a possible catastrophe. POOR Safety Culture at this air carrier; once again; mechanics UNDER PRESSURE to forget about safety first and put on-time performance first. NOT WITH ME! Having been at two previous airlines; one a MAJOR International carrier; it is imperative that this safety culture be ADDRESSED and the hostile environment we are pressured to work in be CHANGED. When is it OK for a mechanic to tell a pilot not to preflight certain items?