I need to span across my 30” stove with a gap. How long are those two expansion pieces together and could I buy more if need be? Are they waterproof?

Thanks for your interest in Armacost Lighting RibbonFlex home. The included connectors are about 6". If you wish to extend them, the best thing to do is cut them in the middle and splice in additional wires. They are not waterproof.