![electrical - Can someone tell me what/how there are 4 wires on one switch and if they're necessary? - Home Improvement Stack Exchange electrical - Can someone tell me what/how there are 4 wires on one switch and if they're necessary? - Home Improvement Stack Exchange](https://i.stack.imgur.com/H0Ui8.jpg)
electrical - Can someone tell me what/how there are 4 wires on one switch and if they're necessary? - Home Improvement Stack Exchange
![4 way switch wiring - Power from light fixture to light switch setup - Devices & Integrations - SmartThings Community 4 way switch wiring - Power from light fixture to light switch setup - Devices & Integrations - SmartThings Community](https://global.discourse-cdn.com/smartthings/original/3X/6/d/6d96c098b2f1fb5accaa4b1373368da6996e1b92.jpeg)
4 way switch wiring - Power from light fixture to light switch setup - Devices & Integrations - SmartThings Community
![I can't figure out how to connect the existing wires in my kitchen light switch to the kasa smart switch. The upper black wire appears to be a common but it doesn't I can't figure out how to connect the existing wires in my kitchen light switch to the kasa smart switch. The upper black wire appears to be a common but it doesn't](https://preview.redd.it/lq2dghry9bj61.jpg?width=3024&format=pjpg&auto=webp&s=43b4d9286a979f8fb3107b49c03e3347fb9cc1ee)