2. tech-talk
  3. 167090-525

Main vs. sub panel for dedicated lines

I am building a second home on my property. Will have a dedicated audio room. I will be routing 2 or 3 dedicated lines for my audio system. The high current devices for the home will be run off the main panel. I will install a sub panel supplied by the main to accommodate power for 2 bedrooms and a 1/2 bathroom.  

Question, should I run my dedicated lines off the main or the sub panel? I could move some of the high current devices to the sub panel if needed.

Thanks in advance for advice. 
mesch
cissado
113 posts
 
I'm confused about the second (set) ground rod for the 2nd panel  issue. I'm familiar with installing two ground rods and connecting to the main panel. Sometimes a second panel (subpanel) is installed on a 2nd floor of a house for circuits in a bedroom, lights, etc... so are people suggesting we run a ground wire outside from there and connect it to a ground rod (or two)? 

A sub panel connection has different rules than a main panel. 
jea48
4,313 posts
 
For a sub panel in an out building, separate building, a ground rod (Grounding Electrode) is required. The ground rod is connected to the equipment ground bar in the sub panel creating a grounding electrode system for the separate building.

For a sub panel located in the same building as the main electrical service panel the separate earth connection ground is not required. If not required why would anyone want it? The separate earth connection can/does cause more harm than good. In fact the separate earth connection can/will add noise to the branch circuit equipment grounding conductors connected to the earth connected ground rod.

This guy has helped over the years in writing parts of the National Electrical Code, (NEC).
Auxiliary Grounding Electrode. (NEC 250.54)
https://www.youtube.com/watch?v=gg4wBI7bWgI
.
mesch OP
3,412 posts
 
Thanks! I am currently away from home and will return by end of the month. I will have my electrician help me install the sub panel. I will use it for my audio system. I will get back to everyone once this has been accomplished. 
lowrider57's avatar
lowrider57
5,397 posts
 
@jea48
Hi Jim, the service I mentioned is the one where you kindly offered advice. Installation was from the drop to a new meter, then inside to a Square D 100A panel, 60A subpanel.

This is a small Philly rowhome where outside the house is pavement. Now don’t freak out, this might be  Philadelphia code; both grounding rods are drilled into the basement cement floor near the rear wall. They’re 3’ apart, sunk into mother earth. I can only see one rod which is wired to the main panel. The 2nd rod is obscured behind my washer/dryer. I will look for the wire.

Question: why are two ground rods used?

I’m guessing the second rod isn’t wired to the subpanel because the main panel is ground, correct?


audioguy85's avatar
audioguy85
2,017 posts
 
What difference does it make? The sub panel is still receiving power from the main panel. Just go to main panel and fit a new 20 amp breaker, or if no room a piggy back breaker. Then use 20 amp 12 gage romex, the yellow jacketed romex. If you like making more work for yourself, then use 10 gage romex...to me, no benefit and way to stiff, over kill....then install a stand alone receptacle contained in a handy box. I’d recommend the audioquest nrg Edison receptacle and cover plate, excellent quality. This is an easy diy project. If the main panel is of 200 amp service, I’m having a hard time seeing the need to add a sub panel. You are in no way going to tax the main panel by running audio equipment.
More to discover