Screw into studs, not drywall anchors, for something heavy that will be above your head while you sleep!
If you're worried about shorting the circuit with your screw, turn the breaker off first.
Measure voltage between hot, neutral and ground, and make sure its 0. Then measure resistance, and write down what you find.
Then try to make sure with the stud finder that you're screwing directly into the middle of a stud. It is then, very very unlikely you will hit the wire. Especially 4-5 feet above the floor!
Once the screw is in, measure resistance again and compare to what you wrote.
If you see a significant change in resistance (>2%) then you might have hit the wire with your screw, and should take steps to repair from it. You could disconnect the outlet in the overhead's junction box, or you could cut open drywall and replace the wire.
But more than likely you will measure no change in resistance, and can turn the breaker back on with confidence that you're OK.
Position the rack so you can screw into the studs. If that is not practical then mount a sheet of decent thickness plywood onto the wall surface and fasten that to the studs wherever possible. The rack can then mount onto the plywood. If you use a plywood that is 3/4' inch (19 or 20mm) thick then the screws for the rack need not even penetrate the drywall at all.
BTW. It is generally (if not always) discouraged to mount anything that will carry significant weight just on drywall anchors.
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The most important part is to start off in the correct location. Once you have started the hole it's relatively easy to keep straight if you take it slowly and have a steady hand.
If your drill has a variable speed - either via a selector switch or by varying the pressure on the trigger - use the lowest speed possible to start the hole. A drill that uses trigger pressure is best as you can start with the drill bit on the mark and then gradually increase the speed. This prevents the bit skidding on the surface.
Once you have the first few millimetres drilled bring the drill up to full speed. You will need to push but don't use your full weight on the drill.
You might find it useful to have someone else watch so they can tell you if you aren't holding the drill perpendicular to the wall.
If you don't have an assistant you can do various things to help you keep the drill level.