I did this for two ide hard drives as I didn't want them running if they weren't being used and I didn't want to constantly be going inside my case to disconnect them. I used simple standard wall switches and occupied two 5.5 inch drive bays to mount them. Electricity is a "mystery" so while "philosophically" fewer switches should work by combing all the grounds, I got the notion that there might be some kind of feed back loop from the psu to the switch and I didn't want that happening--just out of ignorance and superstition. I also note that lots of plugs have more than one ground--so, seems to me that "every" power supply wire needs to be included in a switching scheme. It worked just fine for me, including leaving the data cables attached, for 6 months, then I did something else and actually want to try getting by with fewer hard drives connected at any one time. Superior management rather than hobbies/modification. Its fun though and I smile whenever I come across those switches--all nicely wrapped in duct tape.