In a game I played on the new agricultural update, I was having problems with some circuits overloading, so I started a switch to heavi-watt wire. I only did a small section down a side farm hallway to a couple of lightbulbs that then went down a short section of ladder to a battery on a level underneath. A few minutes later, I had a massive stress problem with some dupes getting above 50% (before the highest was maybe 8%).
In this new update, it turns out heavi-watt wire subtracts decor by a significant amount in a large radius around each segment. In that farm hallway, I had probably 6-7 paintings and 2 marble statues, but my decor rating was -124. Every time a dupe went to go harvest the farms their stress would go up by probably about 25% per harvest (granted these were artist dupes with high decor expectation). Even the ones that used the ladder and passed the farm section would shoot up a couple of points each pass. As soon as I replaced it with normal wire, the decor in the hallway went back to a full, bright green and dupe stress dropped back down to single digits after awhile.
I am not so sure heavi-watt wire is even worth it now with that negative decor rating. Even if it is in side hallways or rarely used areas, the radius is so large, it is going to affect other areas as well. I understand that heavi-watt wire would be seen as disgusting in a base and affect decor rating, but as far as gameplay, it just negatively affects decor too much to be worth using it.