Dedicated Circuits/Isolated Grounds


I’m getting ready to run dedicated lines for a combination Home Theater/2channel setup. The question is how many. I know to run at least two, one for analog equipment and one for digital equipment. However some additional advice for my particular set-up would be greatly appreciated. My equipment presently consists of:

1. Samsumg DLP TV
2. Yamaha RXV1 Receiver for HT processing and rear channel amplification (I may get a processor and a separate amp for the rears in the future)
3. Plinius 9100 Integrated amp for 2 channel and HT fronts
4. Direct TV receiver
5. Sony 9000DVP for DVD and CD (I will be adding a dedicated CDP down the road)
6. Bel Canto DAC 2
7. Velodyne DD12 sub
8. Totem Model Ones (front) and Mites (rear). I probably will not run a center channel.

My current plan is to run three 20 amp 120 volt circuits with 12 guage wire and one 15 amp 220 volt circuit (for the Plinius) with 10 gauge wire. Each amp/sub on a dedicated line, all digital on a dedicated line, the receiver on a dedicated line, and the TV on a dedicated line. What do you think? Over kill, not enough?

Also I’ve heard talk about isolated grounds. Can someone clarify this? Does this mean burying a rod somewhere in your yard separate from the electrical box? Or is it sufficient to ground each circuit back to the box?
jaffeassc

Showing 2 responses by nerspellsner

On a regular outlet the ground screw and pin are bonded to the mounting yolk on the outlet. An isolated ground outlet has the ground isolated from the mounting yolk. In buildings constructed with metal studs,metal outlet boxes are usually also used. When a regular outlet is installed with this type of contruction, the ground is bonded (connected) to all the metal studs in that room and probably the whole building. Electrial noise is introduced into the ground pin of the outlet this way. If an isolated ground outlet is installed the ground will not be bonded to the building metal studs and will not pick up electrical noise. If you install an isolated ground outlet in a metal box you would have to run 2 ground wires the box. One to ground the box and one to ground the outlet. They would both connect to the same ground bar in the panel. The outlet ground has to be insulated so it does not touch any other metal on the way to the outlet. If it did touch metal the isolated ground outlet would be useless. There is no advantage of installing an isolated ground outlet if the outlet box is mounted to wood studs and fed with NM (romex) cable.
Jaffeassc, there is nothing wrong with installing isolated ground outlets in your setup. They cost a bit more and are not needed when the box is mounted to wood studs. You can use regular hospital grade outlets without an isolated ground and save a few bucks. Some people might use isolated ground wiring and outlets if type MC (metal clad) cable or metal conduit is used to feed the outlets even if the metal boxes are mounted to wood studs. The long run of metal surrounding the conductors could introduce some noise into you systemt through the single ground wire connected to the raceway and the outlet. It is a NEC code to ground all metal raceways,enclosures,and boxes. The ground screw to the box must be an approved ground screw and always green in color. You could simply wrap the bare ground wire in the romex cable around the ground screw on the box and then connect it to the outlet. Or use a plastic or fiber outlet box that requires no grounding. Always use the screws on the outlet to secure the wires. Tighten with the loop on the wire going clockwise. If you dont the wire will try to back off the screw when you tighten it. Do not use the push in slots in the back of the outlet. The hospital grade outlets usually have a clamp that the wire goes under and is tightened by the screw. Do not wrap the wire around the screw in this case, use the clamp. Leave 6 inches of wire out of the box to connect to the outlet. Thats a little hard to do with #10 but thats a NEC code too.