Believe it or not, electrical tape doesn't hold as well as the duct tape. You could try it, but be prepared to replace the tape.

Also, you could just set the lamp over the 'air hole' already there. That way you're not cutting more holes (which messes with humidity and temps). Having the lamp hover a few inches over the opening allows for air and heat together.

Just curious, why do you need a heat lamp to keep temps up?