Reckon so, I run a "tight" ship. Top portion has a little slack in it. Never heard of tension being an issue in electrical cords, etc. What's your reasoning on tension (other than causing headaches)?
You don't want tension in the lines, tending to stretch out the copper wire. The wire gets warm with high currents and being stretched and heated/cooled will tend to deform the wire. Look and see how much tension they use on power poles. Mike