Should Subwoofer Be Plugged Into Same Circuit?

I am running electrical lines for my theater myself. Should I make the outlet for the sub on the same circuit as the rest of the AV equipment, or put it on a separate circuit?

i could have sworn I read something that said it needs to be on the same circuit to help prevent ground loops.
Help prevent, yes. Absolutely required, no.

It's pretty easy to tell when you hear it. :)
Run one line, 10 ga copper if you can. Not the cheaper aluminum. One run only, direct from panel to the one system outlet. Plug your power conditioner into it, and plug everything into the conditioner. Or power strip if you're not using a conditioner. 

Hum happens when there's more than one path to ground. But its unpredictable. You could plug into ten different circuits and have no problem, or you could use two and have intolerable hum. Why risk it? One and done. 

This is btw based on actual experience having run several circuits myself and heard the effect of different methods first hand. Also this will be enough no matter how many subs or watts you add down the road. Because contrary to what most probably think the greatest power load is not when the volume is cranked to 11 but the instant things are turned on and drawing full load to fill the power supply caps.

Bit of a shame going to all this trouble for multi-channel. Someday though you may decide to go for sound quality, put a stereo rig in there, and then it will all have been worth it.
It depends on the total current draw of all your components on a particular circuit. Calculate the total amperage that will be used at one time on the circuit. 
And it's best to use a 20A dedicated line which includes 20A wall receptacle and 20A breaker.

I’m in the USA by the way. I get the feeling MillerCarbon May be in another country since we haven’t used aluminum in decades this side of the pond, and I have never heard of using 10 gauge wire for a regular electric run (either 12 or 14).

Thats a good idea on making a 20 amp dedicated circuit for everything if there is even a chance it could increase chances of a ground loop. 
Don’t worry, I have a home theater and a stereo setup, I’m just working on them both at the same time. 
Also, I didn’t think you were supposed to plug everything into a power conditioner. I’m probably wrong because I have never had one but will most likely buy that Brick thinga-ma-bob.
It should be a law of audiophiles that everything should be plugged into one outlet. That is the best way to eliminate ground loops. And sometimes the only way.
I remember you had a thread asking about power conditioners. Most conditioners limit current and an amp draws the highest current of all your components. That's why typically sources are plugged into the PC and amp is plugged into the wall. With a 20A duplex receptacle, conditioner into one outlet, amp into the other.

Depending on the power of your amp, you may be able to plug everything into the Brickwall. It's supposed to be non-current limiting.

To add to the foregoing comments, I suggest that you read pages 31 through 35 of the following document, the section that begins with "this finally explains what drives 99% of all ground loops." It was written, btw, by Bill Whitlock, a renowned expert on such matters.

As you’ll see, the type of wiring can dramatically affect susceptibility to ground loop issues. Romex (i.e., NM cable) is pretty good in that respect. The worst case in that respect is discrete wires randomly positioned in conduit.

My thanks to member @Jea48, this Forum’s foremost expert when it comes to electrician-type matters, for calling this paper to our attention here a few years ago.

Best regards,
-- Al

I’m glad you guys jumped into this convo because I have another question. 
Notice I said same circuit.

i need to branch an outlet off to reach the sub in the corner of the room. 
I don’t see why the sub would have to be plugged into the exact same outlet vice a branch outlet in the corner where there is only the two outlets in the circuit.

please advise.
My guess is that you'll be ok plugging the sub into a different outlet than the rest of the system, on the same circuit. Assuming (per the reference cited in my previous post) that the wiring between outlets is Romex or some other wire type which has the safety ground conductor symmetrically placed between the two current carrying conductors, or alternatively has them all twisted together.

The only way to know for sure, though, is to see how it works out, as susceptibility to ground loop issues is also very much a function of the design of the specific components.

Best regards,
-- Al

Thanks Al! So why is a 20 amp circuit recommended over a 15 amp out of curiosity? 
In addition, @almarg correct me if I'm wrong, one of the receptacles needs to be grounded to the service panel, not self grounded. If there are two separate runs of Romex, then both need to be grounded to the panel to help prevent a  ground-loop. This may also lower the noise floor.

... why is a 20 amp circuit recommended over a 15 amp out of curiosity?
My understanding is that 15 amp circuits are often wired with 14 gauge conductors, although they can be wired with 12 gauge, while 20 amp circuits must be wired with 12 gauge or larger. For a given amount of current 12 gauge will of course produce less voltage drop in the conductors than 14 gauge, resulting in a slightly higher voltage being supplied to the components. (Although if the line voltage that is supplied to the particular location is near the high end of its +/- tolerance less voltage drop in the conductors could conceivably not be preferable, depending on the design of the specific components). Also, of course, with a 20 amp circuit and breaker there is less chance of overloading the circuit and causing the breaker to trip, for instance if the power amp and/or the sub draw large amounts of current for significant amounts of time, during high volume musical passages.

... correct me if I’m wrong, one of the receptacles needs to be grounded to the service panel, not self grounded. If there are two separate runs of Romex, then both need to be grounded to the panel to help prevent a ground-loop. This may also lower the noise floor.

I think your words "not self grounded" are referring to the fact that it is preferable for the safety ground wire to not be connected to metal conduit at the outlet, and that is correct per my understanding. Regarding that also see page 191 of the reference I linked to earlier, which discusses "isolated ground" receptacles. Note that using Romex to connect to a non-isolated ground receptacle accomplishes that by its nature, since there is no conduit.

And of course neutral and safety ground for all runs must be connected together at the main service panel, and they should be and hopefully will be connected from there to a nearby earth ground.

Best regards,
-- Al

If your equipment supports it then a balanced connection between the amp and sub would mean you wouldn't need to worry about ground loops at all and can plug in the sub wherever you want.
I’m covered for all of that conversation. Lol
Also, it’s a powered sub.

I do wonder if AFCI/GFCI outlets hurt an AV system.
I do wonder if AFCI/GFCI outlets hurt an AV system.
I was wondering about that, too.
To avoid ground loops, power connections of all devices should be in a star connection and as short as possible, without obviously exceeding the power capacity of your socket.  So, to get as close to this configuration as possible, it is better to connect all your devices to ONE power socket.

If however, your sub is wireless, this does not matter.  I have mine at home wireless and therefore can plug it to any socket I want without any hum issues.
It should be a law of audiophiles that everything should be plugged into one outlet. That is the best way to eliminate ground loops. And sometimes the only way.
If the system is wired so all the grounds home to a single point, multiple outlets are fine. Recording studios have dozens of outlets with amps, mics, effects, recorders, etc. plugged into them. Ideally with balanced lines and screen lifted at destination. Every studio I wired or fixed was dead quiet with the monitors on S T U N.

Many powered subs do not use a grounded connection, so an additional extension outlet is fine. If the sub is grounded and unbalanced, I'd be wary of a branched line. I've seen grounded unbalanced monoblocks plugged into the same socket hum a little while individually each was dead quiet.

The power loss between ≈50 foot run of 10 and 14ga @ 14A [≈1700 watts] draw is an inconsequential 0.17db. See

A Class B resistive breaker has a 3-5x multiple of rated capacity [For a 15A breaker that is 45-75A or ≈5000-9000 watts] for a couple of seconds. Your voice coils are vapor by then. See

IMO, there is no need for GFCI in a HiFi as there should be next to no chance of water at the equipment.
So if I read between the lines ieales you are saying a 20 amp circuit is unnecessary.

i was curious about the gfci because unfortunately my theater back up to my washing machine in the other side of the wall and has water lines running above it. That’s the trouble with a theater in the basement. Of course a gfci isn’t going to do any good of water is leaking all over the equipment. Lol 
Subs are typically Class D.....don't use much electricity at all  Craigert...I have a gizmo called FloodStop on my water heater, washing machine, water conditioner, etc.  If it senses water on the floor, it immediately shuts it off.  Easy to install....very effective. Get it at Home Depot.
@craigert, being familiar with Ieales’ posts I can vouch for the accuracy of analyses he provides. Also, given the equipment in your system that you’ve listed in another thread, namely:

Sony OLED TV, Marantz preamp processor, Atoll amp, cable box, nighthawk router, Xbox, Rega P3 TT, and powered 12” subwoofer with 2 stereo speakers.

... it seems safe to assume that a 15 amp circuit and 14 gauge wiring of reasonable length (e.g. 50 or 75 feet or so) would be suitable for powering your equipment.

Of course installing a 20 amp circuit can’t hurt, and conceivably could provide added flexibility in the future. I would be more concerned about the drop of a volt or two or three that would occur due to the resistance of that wiring (depending on the current drawn by the components as well as the length of the wires) if a tube amp having unregulated filament (as well as high voltage) supplies were involved. And there are some very high powered solid state amplifiers which can require a separate 20 amp circuit even for each of two monoblocks, but those are big, heavy monsters which typically are at the extreme upper end of the price spectrum. Different animals altogether.

Regarding the possibility of adverse sonic effects from GFCI or AFCI/GFCI outlets, I have no particular knowledge. FWIW, though, my instinct would be to doubt that there would be any adverse effects. For one thing, if significant voltage was being dropped in their contacts they would be heating up significantly.

Best regards,
-- Al


Thanks for the link to Bill Whitlock's paper!
I was aware of the nasty effect from dimmers. Seems the paper is pre-LED lightning emerged. Are you aware of how "noisy" LED power supplies are and/or how to mitigate said noise being injected in the circuit? I'll be making changes to my room and this is a topic I had in mind.

FWIW, lights are on separate circuits in my house.


I have no particular knowledge of the technical characteristics of electrical noise that can be generated by LED lighting, although I understand that it can be significant. I found the following writeup, though, which indicates that the amount of noise can vary drastically among identically rated LEDs, depending on the manufacturer and how they have implemented the design:

Best regards,
-- Al