This stuff is great. I just hooked up my travel trailer light electrical wires: I used a small shrink tube, then over the top of that a larger, longer shrink tube, then finished off the ends with this stuff. Actually I coated the whole darn thing with this stuff. And guess what. The lights did not work. I then checked the ground connections: scrapped to bare metal and tightened the screws down. THEN the lights worked fine. If you hook up your own trailer lights and they don't work, check the ground connection first thing.