I try when possible to use a different color cable than is currently in the building if demo is going to be happening after new cable runs begin. If not feesible I make sure what brand cable is being used, and get a different one for the new, so the demo crew can sign off on being informed which color, and or brand the new cable is before they come on site. I ask the demo scope include not removing any of the brand, or color cable I am installing. If I am doing the demo, I use the same method.
