redearslider.com

I have a few power cables coming out of my tank (filters, heaters, etc...) and I've noticed my turtle biting them from time to time. It doesn't look like he's digging into them or pulling at them, and I've felt the cables to see if there are bite marks or if he's getting through the plastic and he has not. Should I be concerned about this? What can I do to avoid him getting shocked?

If your turtle does't lose interest, then I would suggest using a hang-on-tank or canister filter. You can get an in-line heater (for canister filters), in-filter heaters (certain canister filters) or angle it so the cord is out of the water. Most importantly, use a GFCI... viewtopic.php?f=6&t=29049

Ditto what Steve said.
GFCIs are a must for your turtles safety and YOURS