Dedicated circuits


I just completed installing 2 dedicated circuits. After reading several threads here, I went with 30 amp breakers with 10 AWG wire with high end receptacles. One circuit for the amp and the other for everything else. I’m blown away by the difference. Tighter bass, not as bright, better imaging and soundstage. Should have done this long ago. 

z32kerber

So far I haven't seen anyone question why the dedicated circuit made such a difference. So here is the answer: typical wiring for receptacles is several, often two or more rooms worth, on the same branch circuit. Aside from the smaller consequence of the longer cable run to reach the last receptacle on the branch circuit, the major consequence is the number of splices or receptacles that are in the path. This is a major consequence because the splices are often less than optimal, and where the branch circuit is wired through one receptacle, and on to other(s) it is usually with the backstab connections. A chain of many weak links is what you get, unless you properly pigtail wire each receptacle. 
 

With that myth debunked, let's look at another myth: isolated grounds in dedicated branch circuits. By definition, when you do a dedicated branch circuit run, the ground is isolated. So what do isolated ground receptacles exist for? The answer is in commercial branch circuits, the circuit has a common junction box that each receptacle is wired into, in a hub and spoke topology. This can cause undesirable effects to the shared ground, from eddy currents induced in each spoke. So, where we want a "clean" ground, devoid of such electrical noise, we run a dedicated ground, and use an isolated ground receptacle to keep the noisy branch ground separated separate from the equipment safety ground. 

The breaker handle rating determines the size of the branch circuit, not the wire.

@jea48 okay, I understand that. But what I was getting at was wouldn’t a circuit with Romex and outlets rated for 20A but protected by a breaker that will trip at 15A actually be safer? I mean the 15A breaker should now trip way before the 20A circuit can get hot enough to be dangerous?

@jea48  It's against building code to install 20A outlets on a 15A breaker.  You may be correct that the 15A breaker would trip, but do you want to risk your home insurance not paying out after your house burns down?  Just follow the code and be protected.  It's there for a resaon.  

@bigtwin  , actually it was me, not @jea48  who was wondering about a 15A circuit breaker on a 20A circuit.  Anyway, I am not trying to be argumentative, I was just thinking that if the circuit breaker is designed be the weakest link in the circuit I thought that making it a little bit weaker could only be further protection for the circuit. 

I did a search and found this

Should a 20 amp circuit have a 20 amp outlet?

The amperage of the outlet must never exceed the amperage of the circuit. According to National Electrical Code, only a 15-amp or 20-amp electrical receptacle can be installed to a 20-amp circuit.