Dedicated Line, Surge and Safety

As I'm getting ready to have a dedicated line installed a few safety quesions have come to mind.

1)Will 10-2 wire conduct a stronger surge and increase the risk for damage?

2)Every electrician,besides my electrician,says that using 10-2 wire is overkill and my house will get set on fire. Certainly this is not desireable but all authorities on dedicated lines I've consulted suggest 10-2.

What's the bottom line on dedicated line safety?

Thanks - Jack
Jack, many electricians will tell you that it is overkill. I beleive the electrical code for a 20A line only calls for 12 gauge. However, if anything, it should be safer with 10 gauge. Since the circuit breaker will determine how much juice is sent down the line. Look at it this way, you're installing a 4 lane highway where code only requires 2 lanes. So it should be safer. The breaker guarantees that more traffic won't be sent along just because you widened the road.
That's right. But more importantly, I suggest that you set up TWO dedicated lines, in order to isolate digital components from analog...or at least use your pre-existing house line to maintain isolation. I also believe that using better cable (Teflon insulation) results in better performance most of the time. Many folks know that a cheap-insulation NEW dedicated line can take a long time to burn in, and that an OLD house line, if dedicated, will sound better. (DISCLAIMER: I sell Teflon-insulated Belden cable for dedicated line use). A good compromise might be to set up one Teflon 12AWG line and one 10-12AWG Romex one. Barring that, I'd install two 12AWG Romex instead of one 10AWG...again to allow separation of digital and analog....
How are you gonna handle the ground with 2 conductor wire?
You "believe" the electrical code for a 20A line only calls for 12 gauge, and you think it "should" be safer with 10 gauge. You actually mention twice that you think it "should" be safer. I'd love to hear your repsonse when his house catches fire. "Well, I thought it would be ok."

If you're not actually qualified to give factual, technical advice on house wiring, perhaps you should keep your "beliefs" to yourself.
10 gauge is not any more dangerous than 12 gauge ... it is in fact, safer. 12 gauge is the MINIMUM for 20 amps, not the only. 10 gauge will work fine - as long as it fits in the terminals on your receptacles.
Timo - 10/2 is the standard designation for 2 insulated 10ga wires in combination with an uninsulated ground wire. It's a three-wire cable.
Subaruguru - I'm interested in reading your explanation as to how two dedicated lines somehow isolate components from each other. If you put both lines on the same power leg to avoid ground potential problems, you're riding on the same big bus. Any noise or AC distortion is going to ride that bus, and every circuit on it will be affected. Neither the wire nor the circuit breaker have filters in them, and they flow current both ways.

So can you tell me how this constitutes isolation? If there's something I'm missing, please enlighten me.
Jdombrow, very funny. I figured if he wanted factual information, he'd just listen to his electrician, whom I simply agreed with. I guess I should have simply said to listen to his electrician.
I am not an electrician, but I did sleep at a Holiday Inn last night. Seriously though, I do know a few, and they all will say that 10 gauge is overkill. Meaning you can get away with thinner wire (12 gauge), safely and legally and cheaper. Most folks associated with audio choose for overkill though. Many of us could get by with cheaper and thinner cables in our systems. I had to fight with my electrician to get 10/3 wire, he's a friend who was hell bent on saving me a couple bucks. He simply thought going from 12/3 to 10/3 was a waste of money. When I told him how much my power cords cost, he rolled his eyes and gave in.

Timo- Rex is correct, 10/2 actually has 3 conductors, they don't count the ground conductor. So 10/3 would have 4 conductors.
As Ez2hear said, 12ga is the minimum gauge for a 20A circuit. It's preferred by electricians over 10ga precisely because it's thinner. Thinner is easier to install. If you've ever worked with 10ga NMS, you know it is a major PITA - it makes any job take about twice as long.

12ga works fine for most 20A circuit applications. The only REAL reason to use it (i.e. besides tweaky weird audiophile reasons) is if you have to go a long distance. There's a maximum length spec for 12ga on a 20A circuit, and if you exceed that you need to use 10ga. BTW there's not too many residential situations that would cause you to exceed the max length. An almost sane reason to use 10ga is if you're going from one side of your house all the way to the other and it's a long way, 10ga will cause a little bit less voltage drop than the 12ga. That's one to use on more imaginative electricians.

If you've got one who just stares at you like you've lost your mind when you say you want a 12ft run of 10ga for your 20A circuit, tell him you may need to upgrade it to 30A at some point because your next hobby will be arc-welding! :)
10 gage is not overkill. You're house will not catch fire either by surges or because #10 wire happens to be capable of carrying extra current - the circuit breakers and the grounding system protects against that.

With respect to surges: surges are a temporary overvoltage or overcurrent condition which can cause thousands of amperes to flow. Your circuit breakers are rated for 10,000 amps of short circuit capability - which gives adequate protection for lightning strike surges and arc faults. However, a lot of capacitive energy can sneak through - therefore the purpose of the surge protector. Also, heavier gage wire has a higher fault current capability. For example, #10 wire can clear an 8,500 amp short in only 1/2 of a 60Hz cycle and withstand temparture spikes up to 250 celsius.. a #12 wire can withstand 5,000 amps. That's why a circuit breaker is rated to clear 10,000 amp shorts - a safety factor of two. So, technically, #10 wire offers better protection if by chance your circuit breaker doesn't clear the fault or a lightning surge current misses the ground rod. Now you know more than your electrician.

As for lengths of runs: a longer run will cause a higher voltage drop. Generally, you want to keep the voltage drop to 2.5% or less at your outlet. For a #12 wire, keep the length under 30 feet and voltage drop will never be a problem at max current draw of 20 amps. For #10 wire, you can run up to 60 feet before you have to consider voltage drop. Also, power supplies can operate at spec down to 114 volts (5% voltage drop) so you can double the above lengths and still be okay.

There is another "real" reason to use fatter wire: sound. My monoblock amps sound WAY better when I rewired with 10 wire. #10 wire has less inductance/capacitance to the instantaneous current demand called by the amplifiers.
Rex, the longer the loop distance between the dirtier digital onto its ac line to the analog preamp's input the lower the expected noise floor....
Gs5556, nice post. So why does the 10AWG sound better? It's TOTAL inductance is actually higher than the 12AWG, but maybe not as a ratio to its resistance, or current-handling capacity. If it sounds better I postulate that it's because it stays isothermal through those instantaneous current demands. Yes, 10AWG is overkill in these circuits, as even tiny temperature fluctuations won'y occur except perhaps with the very largest amps. There's some work to do here, as the normal electrical specs allow ratings that reflect a fairly large temperature rise...maybe WELL past what's audible! Is it the voltage drop that's audible or the fact that it fluctuates...or some other consequence?
After consulting with Ernie (Subaruguru) I installed two dedicated lines, one using 12AWG Teflon-insulated Belden wire, and one using 10AWG Romex (for my amps). The difference was not subtle. Before I installed the dedicated lines, I had my entire system powered using the existing, shared line. My amps had been bordering on clipping when trying to drive my Thiel CS3.6's to even moderate levels. After giving them a dedicated line, I never saw the distortion lights flicker even once, even at loder listening levels.

The nice thing about the Belden wire Ernie sells is that if you have any left over, you can make some very nice power cords out of it.

Good luck, Tom.
Thanks, Rex!
Are these wires available at Home Depot?
Romex is available at Home Depot. Belden is not.
I'm glad this question was asked as I am thinking about placing dedicated lines in my house as well.
Shopsmartjazz, The Belden 83000 Series cables can be bought in 100'+ spools from a couple of industrial/commercial suppliers. I do just that, "cure" the Teflon insulations with my EST process, then chop them into custom lengths to resell to you guys on A'gon. It's a whore's business, taking over my office workshop with various unspooled lengths everywhere. Ellen won't even go in there anymore (hmmm....), but I figure somebody's got to do it. This cable is very expensive as commercial stuff goes, given its complete Teflon construction and double-shielding. Even the outer jacket is Teflon, so it's an installer's dream. Belden explains that the 9AWG costs nearly double the 12AWG because there's no real cost saving in doubling the materials because it's offset by the difficulty in making such a hefty cable with fluorocarbon insulations. Teflons sell for $7/lb, vs a few percent of that for PVC. And as we know, oftentimes you CAN hear the difference. I'm not sure that the benefits of using the 12AWG version cable on big amps will offset the possible advantage of 10AWG, but that's why having the 9AWG version is nice, especially for short PCs on my PoBoxes, for example. But using the 12AWG on a dedicated line for preamps, DACs, etc., can be quite beneficial.
(Disclaimer, etc.) Cheers...and Happy Holidays.
To follow up on what Ernie just said, I ended up having him help me make a custom 4-way box with an in-line switch (60A) using the 9AWG Belden (on the 10AWG Romex line). I used this box for my amps. A simliar box (was that a 40A switch, Ern?) was made for the pre/source components using 12AWG Belden on the 12AWG line. I have PS Audio Ultimate Outlets on each line, so a new extension cord was made for each, using 12AWG and 9AWG Belden wire. Both boxes, the non-high current UO, and all wall outlets use PorterPorts from Albert.

I did not have the luxury of carefully auditioning each component (for one thing, my outlets are behind a very heavy entertainment cabinet), but the overall effect is a very noticeable improvement over my prior setup.

Tom, I use the same SPDT 30/30A switch on both the 12AWG and 9AWG PoBoxes, so EACH outlet has overkill 30A rated contacts. Cheers, Ern