Have them drop either when wrenched or broken with a pick, and have them not steal energy from the electric wrench, perhaps unless shift-right clicking.

Fixed

I just tested with IC2 Classic version 1.1.0.19 in survival single player.

I placed a luminator on a tin cable, then tried with three different wrenches.

Regular bronze wrench: Right click and shift right click don't affect it, it merely stays where it was.

Electric wrench in lossless mode: Right click and it flickers on for around 1 tick, then goes back off. Shift right click and nothing happens. No energy is drained from the wrench.

Electric wrench in lossy mode: Right click and it flickers on for around 1 tick, then goes back off. Shift right click and nothing happens. No energy is drained from the wrench.

Breaking them by hand or with a diamond pick causes them to disappear.

As a random aside, when a cable is blown up it still visually connects to those around it, even if the cables it's connecting to are placed after it has blown up.

I placed a luminator on the line, which drew power, above the specified 5 EU/p the cable is rated for, so it exploded.

O.O luminators are reusable when you wrench it... I mean glass breaks also when using a pick...

Wait, weren't they already hand / whatever breakable before ?.... I remember breaking them by hand :P