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Discussion Starter · #1 ·
Ok, I went to Lowes today, and hanging out in the electrical section I got all psyched up and bought the stuff to do a subpanel for my basement. Right now the lights, electrical outlets, theater power, and power into my shop and rest of the basement are all on one circuit.


My thought is to cut that circuit from my main panel, attach to the subpanel, then separate out the lighting, home theater etc. It doesn't change the overall amperage coming into the basement, but separates it out if say my circular saw pops a breaker.


Has anyone done subpanels in their room to split off the HT? Is it overkill? Or does it have some advantages I may not be aware of?
 

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Sounds like you have way too much on that one circuit. I put my basement on it's own panel because I ran out of circuits in the other panel. My theater alone has 4 dedicated circuits as well as 3 shared ones.


1- receiver

2- all other av gear

3- sub-woofer (+ incidentals)

4- projector (+ incidentals)


5-6 shared with adjacent rooms for incidentals

7 lighting -shared with 2 adjoining rooms


(BTW, you can see my sub-panel in my gallery of pictures)
 

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the other day i was in "the little guys",an A/V store in the chicago suburbs..i was talking with there head sound engineer...one thing i remember him saying is that a subpanel for your theater is a MUST!!!i'm sure that was his opinion,but he seemed to know what he was talking about.


brickie
 

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It only made sense for me to include a subpanel specifically in the theater equipment room, but that is because it is a new construction. For an existing house, I'm not sure I'd go through the trouble if the amperage available was adequate.


In your case, it sounds like it might not be. If you're going to be running a dedicated line(s) to the theater room, it wouldn't be that much more work to make it a sub panel instead.
 

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The subpanel is the one thing I regret not doing. I have individual circuits for the equipment rack but a subpanel would have made life easier.
 

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Discussion Starter · #8 ·
Well, I checked my main panel last night, and it has only a 15 amp breaker on the circuit running to the basement. My initial idea for the subpanel was more for convenience, as the lights and outlets and everything are on one breaker in the main, so to do any electrical work I need to cut the power to the entire basement.


Running new cable down there from the main would be pretty difficult. I should know my NEC code by now, but does anyone know what amperage levels are allowed for 14 gauge wire? I know I can't just up the circuit breaker unless the wire can carry the current. I have seen people just put in larger circuit breakers, but of course the idea of the circuit breaker is to protect the wire from melting, so the wire from the breaker must be sized correctly.


It seems like they have 20 amp and 15 amp all on 14 gauge wire - is 20 amp the max for 14 gauge? Do I really need to snake in 12 or 10 gauge wire?


Thanks for all your advice, folks....
 

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14 gauge is for 15a, 12 gauge for 20a, 10 gauge for 30a. If you actually have 14 gauge wire and 20a breakers, you have a potentially dangerous situation. Anyone asking questions like you are does not have the knowledge required to safely bypass the required permit. Make a plan and get a permit before doing this work. If your house burns down and your wiring did not meet code, your insurance company is not required to pay you anything.
 

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One of the best reasons to run a subpanel in the basement is that you can isolate that system when you work on it. My wife was tired of me constantly flipping the main breaker on and off. With a subpanel, she is not affected by my never ending science project.


Along those lines - if you are running water lines in the basement for a wet bar, it is a must to initially install valves when teeing of the hot and cold water pipes. Again, you won't have to constantly shut off the water and drain the hot water tank when you need to work on the system.


Just some of my experiences.....
 

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Installing subpanels, as opposed to merely adding circuits to the main panel, is done for three reasons:


1) Increasing breaker capacity of existing panel (quantity of circuits, not amperage).


2) Adding several circuits in an area away from the mian panel (can be more economical to run one heavy cable than many smaller ones, and lowers voltage drop over distance).


3) Localization of load center for convenience of use, to bring control near point-of-use.


Empire needs to know that there's no advantage to adding a panel to a single circuit. Plus, how much space is left in his existing panel? For convenience of keeping the lights on while doing other wiring, he could simply use several switches.


Theoretically, he could wait and see if the theater equipment ever causes a breaker to trip. If he's never had this problem before, and doesn't use the rest of the basement at the same time, he might be okay.


Also, the intended new gear is a factor; a TV and mid-line receiver would probably be okay on the existing wiring. If he's going with a high-power system and projector, as well as new lighting, then he's definitely going to need more ampacity.


As far as the necessary new capacity goes, anything short of a kilowatt-rated system would be more than happy on a single 20-amp circuit, and the lighting should be okay on the existing circuit.


If one needs more capacity than that, and/or is adding a lot of lighting or other wiring, a 30-amp/240-volt sub-panel, fed with a 10/3 (plus ground) cable and a 2-pole/30-amp breaker would provide plenty of power, and could easily handle four or six new circuits.


In my case, I ran a 50-amp/240-volt panel, fed by a 6/3 cable. Why? Because (1) I'm an electrician, (2) my system is in the 2+ KW range and includes a CRT PJ, and (3) because I will be adding lighting some day. I used eight 15-amp circuits, by the way.


Greywolf is right on the money with the wire size/ampacity numbers. If you overload a wire, it overheats and damages the insulation, which leads to fire, the #1 danger of electricity. Electrocution is #2.
 

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Way too much for a 14 wire. Put the lighting on the 14 run and run two or three 12s to the basement or do as Larry suggests and run a single 30 (10-3) amp to a sub panel in the basement and branch of from there. It may look like a real job for you but an electrician will know how and where to run it.
 

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Discussion Starter · #13 ·
Folks, thanks for your comments.


Just to clarify, I do not by any means plan to put 20 amp breakers downstream from a 15 amp breaker, or do anything against code or dangerous nor do I recommend this to anyone else.


To restate my original post better: Without changing the overall amperage of the circuit, is it worthwhile to split the one circuit from the main breaker into four independent circuits for the basement.


"One of the best reasons to run a subpanel in the basement is that you can isolate that system when you work on it." was the kind of thing I was wondering about.


I do understand the impact of too large breakers on different wire, but I appreciate the list from Greywolf as I wasn't sure what current maximums were for each gauge wire. If I do start tripping my breaker, I will need to snake in some new wire.


As more information for my project - I have a half finished basement which I am finishing the other half, adding lights and electrical outlets. To do this with all power off and working by flashlight seems to be the alternative to separating the lights and the outlets. I am in a 15 year old house with no easy way to bring in new wire from the main panel to separate circuits at the main panel other than cutting into the drywall in several places.
 

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To likewise restate my answer, there is no advantage to using anything downstream of a properly-sized-for-the-wire breaker. A 20-amp breaker downstream of a 15-amp breaker would simply provide you with a breaker that will never trip.


Switches would provide the same split-the-single-circuit-into-several-separate-ones isolation you're seeking. Bring the wire into a two- or three-gang (or whatever suits) switch box, and you can have one switch for lights, one for receptacles, etc.


Keep in mind that original wiring usually has no regard to separation of lights and receptacles since, with the exception of appliance circuits, receptacles are considered lighting outlets; the switches are probably wired in with the receptacles.


You'd likely have to re-wire the entire basement's wiring to separate the lighting from the receptacles, which will invole a lot more wall-opening than adding a circuit or two. Adding to an existing circuit is a bad idea; they used one original circuit for a reason.


Doubling the finished area of your basement will certainly be too much for a single 15-amp circuit. Re-consider having a new home-run or two installed; experienced electricians can usually fish wires with little or no wall opening/patching.
 

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Discussion Starter · #15 ·
Thanks, Larry. I didn't quite catch your switches idea the first time around, but that does sound like a much more economical approach to splitting the circuit and would have the same effect electrically as circuit breakers other than tripping on overcurrent which will be provided by the upstream 15 amp.


Sounds like I'll need to look into a new home run circuit though before I put too much on the other side of the basement. Thanks for the advice...
 

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One thing I've never understood about amperage and subpanels...


I have 400amp service to my home (it was to feed my home and a shop/garage with 2 meters.) Currently only the home is connected via an exterior main disconnect, rated at 200amps. I then feed about 50' through 3" conduit using 3/0 cable to my inside box, which is also rated at 200amps. This box is physically full except for 2 spaces. What happens to the ratings if I take those 2 spaces, and feed a 50amp subpanel in my theatre? This is what I've never understood...I realize that the panel will never reach full capacity unless every outlet/light/switch/appliance is drawing max at the same time, but how can adding that subpanel not affect the overall system? This is something I have considered doing, as I also have a CRT and fairly high powered audio system. I'd also like the ability to add lighting in the future and only pull from a nearby panel rather than the other end of the home. I'll start reading these links now :)
 

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Jay,


Nothing happens to the amperage ratings by adding a subpanel. All you are really doing when you add a subpanel is increasing the number of available slots to install breakers in. The overall maximum amperage you can pull is still the same as is dictated by the breaker in your main panel.


If you add up the amperage of all the breakers in your main panel, you'll likely find that you are WAY over the total that your main panel breaker is rated for - at least that's the case with my panel. As long as you are not drawing more than the maximum amperage your main breaker is rated for, it does not matter how many breakers you have in your main panel or any additional subpanels you have connected to it. It's all about the concurrent usage of electricity on circuits that you need to be concerned with...


Dwight


By the way, I'm not an electrician. Larry Fine will correct me if I screwed up anything in this posting, but I'm pretty sure that I've gotten it all right...
 

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Quote:
Originally posted by dwightrahl


By the way, I'm not an electrician. Larry Fine will correct me if I screwed up anything in this posting, but I'm pretty sure that I've gotten it all right...
No, Dwight, I can't fault your explanation, just maybe embellish it a little.


The total current used by your house does not depend on the quantity of circuits that are used. Adding a sub-panel fed by the main panel is no different, electrically speaking, than tying the same new circuits directly into the panel.


Equipment ratings refer to the maximum allowable current capacity. The actual current usage depends on the equipment you have connected and running at any moment. You can add many new circuits and the current use will not increase until you turn on the new equipment.
 

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Quote:
You can add many new circuits and the current use will not increase until you turn on the new equipment.
And other than teh worksheet provided earlier, there is no other way to establish whether you have a large enough box or not? When I go to any _insert any name_ home improvement store, they seem to have predominately 200amp panels. Am I to asume that 200 amps would serve almost anyone? Within reason of course.
 

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200 amp entrance is the standard today. It would be rare to see someone update their service or a new home supplied with less than 200. The cost difference is negligible to use less. However there are many good sized homes out there with 100 amp entrances operating with no problems whatsoever. If you have a 60 amp entrance you definitely would want to think about updating to 200 but just because new homes are now at a 200 amp standard is not a reason to run out and spend 1500 bucks (around here anyway) because you are adding a couple more 20 amp runs to your HT.
 
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