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Discussion Starter · #1 ·
I'm about to get estimates on installing a dedicated panel (? or is it circuit) for a HT. I've noticed the mention of 20 amp vs 15 amp circuits? How does this make a difference. I know that some amps (like the EAD's) can put out more power with a 20 amp circuit but what about other amps or equipment. Does 20 amp just give more potential, or does it mean more draw for the equipment? sorry, I know nothing in regards to electrical work (or wood work, or drywall, or..). Just wanted to sound somewhat informed when I talk to an electrician.


Thanks,

Andy
 

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It provides more potential. It also provides a means to put more of the equipment on fewer circuits minimizing grounding issues. Personally, I run pretty much everything - AV or not - on 20 amp circuits. You never know when you might want to add something to a circuit.


The difference in cost is minimal for the breaker but more for 12 ga wire over 14 ga for a 15A circuit. However, being able to only have say 2 circuits for basement lighting vs. 3 can help recoup the cost due to fewer long home runs back to the breaker box. This also leaves more space in the panel for future additional circuits if you need them.
 

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I actually had a subpanel in my basement so I did a bunch of 15AMP circuits. Wired up 6 circuits, and doubt I'll ever reach that for each one.


Here's what I have in case you were wondering:


Home theater - lights

Home theater - recepticles

Equiptment closet

Den/Hallway recepticles

Den/Hallway Lights

Closet Lights/Recepticles


Worked out nicely. It's pretty tough to hit 15 amps on a circuit as it is. The only one in question may be your equiptment closet...
 

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hard to explain without confusing myself :/


having more current means you have less resistance (given Voltage is constant)


a 20a circuit can handle a greater load than a 15a circuit.


Personally i have planned for a 20a circuit, but only because I want a dedicated circuit for the HT equipment. Everything else will be run off 15a circuits.
 

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Discussion Starter · #5 ·
Thanks guys. I'm in an older house and everything else is 15a, I think. I just wanted the equipment rack and the pj to get the 20a. I guess thats the way I'll go. But just to make sure, it just means more potential. Electronics are not going to fry just because its plugged into a 20a circuit, right? Hate to hang the pj and have it fried.


Thanks again.


Andy
 

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That's right. The current draw is determined by the load. The wiring and associated hardware needs to be able to handle the load. If the pj is the only load for example and if it draws maybe 6amps, there will be 6amps running through a circuit with the ability to handle 20amps peak and 16amps continuous.
 

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Let's separate the current capacity from the voltage drop.


Voltage drop is the difference between the voltage at the circuit's origination and the load. This is dependent on only two things: the circuit resistance and the circuit's current flow. E (volts) = I (amps) x R (resitance).


You can always use a larger wire size, 12 instead of 14 for example, and still render it a 15-amp circuit by using that size breaker; the inverse is not doable. The breaker protects the wire from overheating.


The load expected on a circuit is what determines the best wire for the job. Lighting is generally a consistant load once calculated. Electronics is more variable, and more sensitive to voltage variations.


What's important is that the labor cost is the same, the cost of the breakers is the same, the devices (receptacles and switches) are the same, and the wire cost difference is about 25%, so choose by need.


Whether to run a sub-panel instead of individual circuits depends on (a) the distance, (b) room in the main panel, and (c) the importance of individual load diversity (one overload not shutting down everything).


A large feeder will exhibit much less voltage drop over a distance as compared to separate runs, especially since few circuits will be loaded simultaneously. Plus, a subpanel gives a great fun factor!
 

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Everything new I'm running is 20 amp, using 12 gauge wire. While the benefits are described, using 14 gauge is easier in terms of installation. 12 gauge is stiffer, making twisting, connections, etc. a bit more difficult. Worth it though.
 

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to add to what larry said, and to expand a bit, the way you wire your fixtures/receptacles also plays a part on the load you'll be seeing.



If you're running series your voltage and resistance will vary from one device to the next, but current will remain the same, and if you run in a parallel setup your voltage is the constant, and current and resistance are the variables.
 

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I can't think or any fixtures that can be wired in series to a 120VAC source. Certainly receptacles cannot be wired in series.
 

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Discussion Starter · #12 ·
Thanks a bunch guys. It amazes me how much info is available here on the forums. Quick question, how much would one expect to pay a licensed electrician to either do a dedicated circuit to 3 outlets or to create a subpanel for 3 outlets. Relatively small one story house with attic and crawl space to run "stuff" if needed.


Thanks again for all the info.


Andy
 

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Andy, the single hardest part of the job is getting the home runs into the panel, especially if it's on an outside wall. Rough range: Circuit w/3 receptacles: $150 - $250. Sub-panel, $250 - $500. Parts included.


By the way, the only thing wired in series in a house is a switch and its load (unless you count things like breakers & fuses, and low-voltage-bulb X-mas lights. In other words, every circuit is "series"wired.)


Some people call the usual two-screws-in/two-screws-out "series, and pigtailing "parallel. Electrically, there's no difference. Pigtailing merely removes the screw connections from the downstream circuit path.
 
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