AVS Forum banner

Electrical service for subs and main amps ??

4K views 56 replies 16 participants last post by  kgveteran 
#1 ·
I plan on running four separate electrical lines with four separate breakers for my current build. Three are for amps and the fourth is dedicated to all the lower voltage gear and a thousand wall warts Lol.

My question is do i use two runs of 12/3 or four runs of 12/2. I will have more common wires and ground wires with the four separate romex runs, will it really matter ?
 
#2 ·
KG, since I did a bunch of electrical on my place last year, and had it inspected, I suggest you run separate 12/2 lines for each new circuit you're adding. My house has a situation where the previous owner (or maybe it was me, I honestly don't remember) ran a 12/3 line to the kitchen where one side of it goes to the dishwasher and the other side goes to the garbage disposal, sharing a neutral. Each side of the line was connected to a separate breaker. While it wasn't a problem to share two circuits over one 12/3 wire run, the inspector had me install a little bracket between the two breakers so that if one breaker trips, both sides will trip.
Just keep it straightforward and run separate 12/2's for each circuit. I can recommend a good inspector if you need one afterwards. I've used him a few times.
 
#4 ·
I will have more common wires and ground wires with the four separate romex runs, will it really matter ?
The main issue will be the potential for ground loops with the separate ground lines back to the service entrance. I'd have all the outlets in a common metal enclosure so that their grounds are all connected by that enclosure at the point of use. Another option is a break out box at the point of use, connected by a single large gauge wire to a 220 breaker in the entrance. That's how it's done in pro-sound, where multiple amps are commonly used in the same rack.
 
#8 ·
I have no clue what you said. could you provide a schematic I could look at. I would do a search as to what you said, but wouldn't know what to search. I would like to weigh my options.
 
#5 ·
The potential for ground loops is low - extremely low - and there would have to be measurable ground current, one device, with another device having a lower resistance path to ground than the first device to create an issue. In 4 12/2 romex runs to the same place - I don't see that happening. 12/2 is the way to go. If you use 12/3 with shared neutrals, you should have each breaker on a separate leg of power (I don't say phase because the two legs are in phase but out of polarity), and the breaker should be tied together. Also note, that if you used 12/3 and the neutral ever became loose or was otherwise damaged, your gear would be running in series with what is on the other circuit - think about that for a minute... and you will want 4 runs of 12/2.

Though - I second Bill's suggestion that a 60A or 100A sub panel or something like it with one run of big wire makes more sense to me. Then when you trip a breaker with your bass, its a short trip for a reset.
 
#10 · (Edited)
A typical arrangement is to run 10ga cable from a 30A-30A 220v breaker to a box at the point of use and split it there to four or more 110v/20A rated outlets. That's 60A total at 110v, which should be plenty. If this doesn't make perfect sense to you it should to a qualified electrician.
I get it now, a run of 10/3 could provide 220v to a sub panel, then (4) short run from the subpanel to my equipment rack.....would that be correct ?

One side note, the location for my equipment rack and my main panel box is about 70' apart, so four runs of 12/2 70' long would have a common ground 70' away opposed to 4' away........

Is this a correct understanding ?

...... and while were at it. I should provide enough wire support if i ever need more at that sub panel. Is 10ga enough ? I will need four 20a breakers at the sub panel and, what load breaker in the main panel, dual 40a ? The distance is 75'. Is there any difference between aluminum or copper wire ;0)
 
#6 ·
I walked the path you seem to be on.

I ran a line to a sub-panel. Inside that sub panel, I ran four lines to my room. Ran them into the closet and have a bunch of outlets on each line (picture below, each column is dedicated to a location, left column is dedicated to front left, second column is dedicated to center, 3rd column, right front and 4th column is dedicated to the items in the closet)

Wanted some switched outlets so ran some 12-3 wires to the switches.

Every single outlet I have, literally every single one, is switched on top and hot on bottom. Again, everything is tied to the switches on each circuit.

Made for a lot of work but i have tons of outlets. My wife hates the orange color! It is however, easy as pie for her to turn things on/off. Just hit the 4 switches and everything is on, relative to how you turned it off.

No hum issues. I was worried about that. Soldering the connectors in the closet was a pain in the rumpus-maximus.
 

Attachments

#11 ·
Wow there are a lot of outlets in some of these builds. Myself I wouldn't want to do that much wiring or drywall work and would stick with one or two high amp twist lock outlets and use PDUs. If you have good amps that support 220v (most pro ones do) then include one 220 outlet and one 120v outlet otherwise do two 120v ones.

There are some pretty crazy PDUs out there such as this dual 120v circuit example: http://www.tripplite.com/pdu-power-distribution-unit-40a-dual-independent-20a-120v-circuits-0u-vertical-nema-5-15-20r-outlets-dual-l5-20p-5-20p-single-phase~PDU40TDUAL/
 
#12 ·
You're getting in deep now! If you are hoping for (4) 20 amp breakers, that's an 80 amp sub panel, which is what I put in my garage (I actually have a 100 amp box out there but I'm using an 80 amp breaker in my main panel to feed it). I had to use 2/0 4 conductor aluminum service entrance cable to run from my main house panel to my garage panel. It's not cheap, and it's no fun to work with.
If I were in your shoes, I would buy enough 12/2 to run your 4 circuits to where you want them. Once you get into installing a sub panel, you're in deep assuming that you want it inspected so that if your house burns down you'll be covered.
 
#17 ·
So 70 x4 is 280 feet. Plus waste and misc.

One run of heavier gauge would be more money per single line but cheaper than 4 or more.

If you run a sub panel you have expansion options. Plus you can do multiple smaller load circuits dedicated for your various lighting and other stuff. That won't take much power but it's nice to have dedicated and labeled breakers and circuits. Now you could have 8 total circuits like for example (4) 15a and (4) 20a. I think the cost difference would be small when you factor in the upgrade-ability and ease of install on the backside. Once that panel is up everything is easy.

Or if you want to DIY but ar uncomfortable with the sub panel you could buy and mount the panel and wire everything up to it yourself, and then just pay an electrician to hook it into the main panel and energize it. He could overlook all the work too, and validate it's safe and done properly without you having to pay top dollar for a professional to do all the work.
 
#18 ·
Yep, build your cable run heavy to point of use. Upgrade your breaker box to handle the additional heavy circuit if need be. If I were doing it myself I would provide an overcapacity of 20% simply because in the future you may need to plug in more equipment/larger equipment etc. Saves you doing it all over again during upgrades. If you do it yourself an electricians inspection near the end of the project is a good idea. Have fun!
 
#19 · (Edited)
So, it looks like 100amp wire is needed. The numbers look like gauges 2-2-2-4, or 100amp sub feed cable.....

Is there a need to breaker my sub panel, or is there another way to connect to the main feed in my main panel. I would have to get a 100amp main shutoff for the sub panel.....
 
#24 ·
Went to Lowes, got ahold of an ex electriaian lowes emplyee and started my laundry list of parts......

Lets just say after about a thirty minute conversation he asked me why not just run four 12/2 lines and be done with it. It will be exactly the same electricity and you saved a ton of money and time.....Sounds like a plan to me :0)
 
#25 ·
Sounds like a good suggestion! lol
I was gonna say, in regards to cost, I spent $3-400 all said and done to do the subpanel in my garage, fill it with breakers, and run some 120v and 240v outlets; and this was with already owning the panel itself! Service entrance cable is not cheap.
 
#34 ·
Once you blow them once or twice they are spent, toss them. Annoying given their cost. I smoked one running very little current (15a)

No more 15a allowed in my house. A 20a cost only $0.65 more, worth it. A little extra for some 12 instead of 14, perhaps a buck here and there for 20a outlets... All money well spent if you are starting fresh.
 
#31 ·
When you guys talk about running sub panels, are those basically separate breaker boxes that are located somewhere in the home physically apart from the main breaker box? In the case of adding a separate sub panel, would it have a single wire connecting it to the main service panel/breaker box?

I have been wanting to run some additional 110v lines to my sun porch which is currently doubling as my shop (it's big) so as to not have to constantly drag the extension cords around. problem is that it is not possible to run another wire to the breaker box due to its location and the design of my home.
 
#33 ·
A sub panel can be located anywhere: in house, in shed, in garage, wherever code will allow. Keep in mind that disconnects may be required if the subpanel will be installed outside the home (like a porch - you'll need to check your local codes). The sub panel is supplied by the main service panel. Below is a quick image to get an idea.

I installed a 100amp subpanel in my home which required a 100amp breaker in the main service panel. I then used #6 wire to connect the 100amp breaker in the main service panel to the subpanel. The #6 run is 4 wires. Hot leg a, hot leg b, neutral, and ground.

 
#35 ·
Thankfully, arc faults are not required where KG and I live. At least, the inspector that I used (who is also a code instructor), did not mention me having to have them.
For my above ground pool power outlets, I chose to use arc faults in my main panel instead of having to use specialty GFCI's at the pool.
 
#38 · (Edited)
I run 12 gauge always with 20amp circuits, but I over build everything like almost everyone in this sub-forum
Hole hog'd for four runs of 12/2 and will be done with this leg of the install soon enough
 
#46 ·
If you passed, that is all that matters for resale and insurance reasons

I wasn't implying you were wrong or I was right... I literally just found it hard to believe an area hadn't adopted 2011 standards yet. Your replacement scenario makes sense though

I gotcha and it's all good. I am pretty convinced that my situation was acceptable because of the not adding new circuits to an existing dwelling thing. Looking at my local town code docs this morning, it states that my town does comply with current code and actually has even more stringent restrictions in some cases above and beyond what state code requires. I ran into that with the wiring for my pool pump.
Either way, I'm glad I'm in the clear.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top