When do I need to use a shielded cable? Are there any downsides?Updated 7 months ago

Use shielded cable if you cannot avoid getting close (in parallel) to AC electrical wire, electrical motors, or have other EMI/RFI issues that you are aware of. Crossing electrical wire at right angles is OK. The environment will dictate when and how shielded cable should be used. We have a handy table for this in our blog Top 2 Things to Consider When Running Ethernet and Power Cable.