Axiom Home Page Forums General Discussion Advice from Axiom Owners Dedicated Line for Amp?

We are getting a bit off track on how wiring affects audio ... so feel free to skip this post ,.. i.e. "these are not the droids we are looking for ... move along".


The gauge of wire is dependent on two things ... amperage and length. Since I don't know the code for this I can just tell you what I have in my house (built last year).

Most if not all 120V outlets are wired with 12/2. Most if not all 120V lighting was done with 14/2 and 14/3.
I'm not sure if 12/2 was required as a minimum for all 15A outlets or if it was just easier to use it for all outlets without keeping track of the run length.

That's interesting. The electrician said they were required in kitchens too ... at least in Massachusetts. Unfortunately the inverter in our microwave kept blowing it. I ended up just getting a different microwave. Less often, I have the same problem with my shop lights. Not sure why I have an arc fault on them ... perhaps because the downstairs bedroom light is also on it? I'm pretty sure they would not have used one if code didn't require it ...be nice to know the reasoning ...

From what I understand the difference between commercial grade and residential grade is durability. Outlets like all connectors are only guaranteed for a limited number of swipes before they wear out. (I.E. Swipes on Residential grade << swipes on Contractor grade.)

I do not know if the contact resistance is any better ... but it has to be reasonable on all outlets otherwise they would be a hazard. It does make sense that if the outlet is worn thin then you'll have a higher resistance. So in places where you are constantly plugging in and out stuff, like the kitchen, you'd definitely want the higher grade ...

On contact force ... guess I should qualify that this is educated reasoning rather than hard facts ... just applying what I know about connectors to stuff I know about outlets ...

Once you reach a force that wipes the contacts clean (so you get a good connection) extra force may just result in extra wear. So there are trade offs. Hospital grade outlets have a high contact force mainly to keep the plug from being accidentally pulled out. I'm sure they are designed for long wear too (probably by having a thicker layer of contact material) making it more expensive (but not necessarily better)

We have no tamper proof outlets ... most likely it's a state requirement.

I no longer have a COF, so I'm not inclined to give wiring advice or get too deep into NEC interpretation. My earlier comments were about generic wiring of circuits and the rationale around a dedicated "line" for the EQ Rack, verse adding a receptacle to an existing circuit.

Having said that, in years past (not too long ago either), 12/3 was used throughout a structure for 110V/120V. It was quicker and saved effort with respect to running wire between the panel and the first Jbox, or just drilling holes in studs and joists for the romex. For example, I would run a length of 12/3 to the first convenient box in a bedroom where I planned to install 4 duplex receptacles. Per code at the time, 8 receptacles was the max I could feed from a 15A circuit. Well, the room also needed a couple of receptacles for lights and/or a ceiling fan. I would use one of the line conductors for the receptacles and the other line conductor for the lights, running 12/2 to the rest of the room box's. That left one N and one G for both the lighting and power circuits back to the panel.

This method of pulling/installing romex was common in the industry. It can cause issues though. Some light fixtures send weird amounts of current back to ground through the neutral, and sometimes, this is enough to create "noise" on the circuit used for the receptacles. I've seen enough stray current at times to trip a GFCI receptacle before. It can also be a PITA to troubleshoot.....

Nowadays, you just don't wire a house or other building using 12/3 for 110V/120V. 12/2 is used. This enables the wireman to do whatever he/she needs to do with the neutral wire back at the panel. Sometimes you only need to land it to the bus bar, or you might run it to an AFCI or GFCI breaker.

So back to the original question.....is a dedicated line needed? Yes, I think it is. And no, I would not consider adding a receptacle to an originally installed circuit a good idea, - unless that circuit is home ran (both L and N), and it has capacity for the added receptacle.

And I always use 12G wire (copper solid strand). I don't screw around with 14G. Not many electricians do. 12G is good for a 20 amp circuit, 14G isn't, well usually isn't.

For new construction, AFCI circuits are the norm if GFCI is not needed. A lot of electricians run combo circuits. The electricians I work with tell me it the next NEC will most likely call for all residential circuits to be AFCI, with exception of those that require GFCI.

For the receptacle, I have a preference for hospital-grade. They are stout as hell, near impossible to break when landing wires, and will outlast the home. More expensive, but not really that much more when you look at the total installed cost of the system.

Hi Micheal ... all you said makes sense to me. I think we are not in disagreement. I now understand the 12/3 and 12/2 stuff you were talking about. I also understand why one of the electricians told me that 2 phase and single phase shouldn't be in the same box ... didn't get that one till you mentioned the common neutral and the problems it causes.

BTW: what does COF stand for in your context ... I only know it as Certified Old Fart

Oh, one more thing ... I might be wrong on this but don't the AFCI breakers also include ground fault detection? I'm pretty sure mine do both ...

We have no tamper proof outlets ... most likely it's a state requirement.[/quote]

It may be anything below a certain height, I can't recall, but we ended up with tamper proof outlets throughout to simplify.

Bedroom lights have to be on AFCI and outlets do as well. We could have wired bedroom outlets off one breaker but ran two for each room since we have 400amp service and plenty of room. The vacuum cleaner will still trip the AFCI once in a while especially on the wall wired in with the air purifier and tv plugged in and on.

We did run 14ga for lights instead of 12ga. I agree I think eventually 12ga will be required throughout although lights don't pull much current.

If they go to AFCI on everything it's easy to swap out the breakers and we wired everything not to overload any one breaker.

C.O.F. - Certificate of Fitness. I moved into management many years ago and just couldn't keep up with the required continuing education and time to study/sit for exams to keep mine current.

There are combination AFCI/GFCI breakers now. They open if either ground or arc fault is detected. Expensive and somewhat new'ish tech, but are becoming more mainstream..... Single-function AFCI or GFCI do not protect for both faults, to the best of my knowledge.

Just for clarification, the vast majority of residential wiring is single phase. Two-phase power generation was replaced by three-phase power decades ago. The residential feed is two 120V legs of three-phase power supply from the transformer, with one neutral. Commercial power will generally have all three phases ran to the building. So technically - your home is single phase, even 240V circuits.

12 AWG for lights IMO is overkill in most residential homes ... if anything the power needed for lighting has been going down. For years 14 AWG was used when most all residential lighting was incandescent. Then most switched to CFL (which consumed much less). Now most residential lighting is heading to LED. So, lighting is using something between a 5th to a 10th of what it used to. Some numbers off the top of my head ...

an efficient non-dimming led light can give you around 100 lumens/watt,
a dimming one a bit over 82-85 lumens/watt
an incandescent about 11 to maybe 15 lumens/watt.

Now all that said some people still insist on only putting in incandescent ...

Well, guess you can look at it that way (maybe). I see it as 2 of 3 phases each giving 120V to neutral. If you take the difference between the 2 phases you get 240 ... but hey, I'm an engineer ... it's hard for me over simply stuff because although it gives an idea of what going on ... it's just not quite right.

This especially bugs my wife who just wants simple two second explanations. She gets really impatient if I give the two minute one, I think, because in most cases it's completely unintelligible to her.

For example ... I'd say one thing and she hears:

A base plate of pre-famulated amulite surmounted by a malleable logarithmic casing in such a way that the two spurving screws are in a direct line with the panametric phlam, so fitted to the ambifacient waneshaft that side fumbling is effectively prevented.

2 phase lines are 90 degrees apart electrically. 240V house power is single phase and is sometimes called split phase.

Rich, maybe it's best your wife just sticks to the reality she knows best.

Every time I'm out
I'm full of doubt
In the world of the material bazaar
Outside I feel
Is not really real
Am I sensing things as they really are?

Inside I find
A trustworthy mind
Freed from illusions blurred
The thoughts that appear
Are so crystal clear
Mind over matter preferred

That leaf that I glean
Is not even green
Nor it's shape so simple, distinct
It's a fact that the green
Is but a smokescreen
And the shape is wavy fields linked

But inside my beef
A leaf is a leaf
No blurry senses buffet
There is no deception
Upon leaf's conception
No mind games whatsoever at play

Yep, your house is single phase 120V. To get 240V you are running a double pole breaker and sending 120V twice.