do i need to turn off/unplug uno while wiring up a circuit?

Simple question but I can't find an answer anywhere. Do I/Should I turn off the Arduino when hooking up or making changes to a circuit? Or can I leave it plugged into USB?

thx!

forgetcolor: Simple question but I can't find an answer anywhere. Do I/Should I turn off the Arduino when hooking up or making changes to a circuit? Or can I leave it plugged into USB?

thx!

Should I? Yes I should always. Do I? Not nearly as much as I should. ;)

Lefty

Have I blown up chips making changes while powered up? Yes!
Power down/unplug from USB when making changes.