Here's a little trick to keep you from damaging your shore power cable. Start to Extend the cable from the outside, then go inside and push the cable out to the point that all is deployed except for a little remaining inside. Wrap a few inches in red duct tape. Now you have a visual que as to when to stop pulling out cable from the outside. The point being you don't want to pull on the cable, stressing the connections to the electrical system.