A shielded locking system for securely closing a lid on an enclosure, such as a grade level utility vault, including an L-bolt connected to a spring-biased slide member positioned on the underside of the lid that rotates in a slotted housing that securely retains the L-bolt under the lid, the slide member engaging an abutment on the inside of the enclosure when the lid is forced down over an opening in the enclosure by downward force on the lid which progressively causes the latch to retract against the spring-bias from contact with the abutment and then snaps the latch into a spring-biased locking position under the abutment, and a non-conductive cover positioned over and connected to the locking system to shield the L-bolt from electrical conductivity from within the enclosure.