Is a 20 Amp circuit enough to run a home theater?

S

shadyJ

Speaker of the House
Is a 20 Amp circuit enough to run a small home theater?
How much do you really need to run a small home theater?

Ex:
AVR 7.1.4 Surround
Amp (600 watt?)
Sub
Home Theater Seats
Blu-Ray Player
Projector
You will want to pay attention to how much power each piece of equipment draws. I would be looking at higher-sensitivity speakers, if possible.

I would also very much go for multiple subswoofers, and large ones too. The reason is it takes less power to produce bass with multiple subs- it's far more efficient. To get double the output from a single subwoofer, you need four times the power. For example, if your sub is using 10 watts to play at 90 dB and you want to double the SPL (in other words, you now want 96 dB), you need to increase the wattage to 40 watts. However, if you simply add a sub, that grants you an additional 6 dB for only half the power draw increase. Large subs are more sensitive than small subs, so a modest amount of wattage will go further with them. I would look at getting a couple of 15"s if it is in your budget.

Also look into good light control for your room, so you don't need a light cannon of a projector to get a good image. A good, bright screen can help here too, by giving you a nice vivid image without needing a ton of wattage going to the bulb.
 
mtrycrafts

mtrycrafts

Audioholic Slumlord
One reason to have a 20A receptacle is that you are ready to use a 20A appliance in that circuit without replacing the receptacle. An inexpensive pre plan.
 
panteragstk

panteragstk

Audioholic Spartan
The other thing to consider is that even though you have a 15A receptacle doesn't mean the attached equipment is limited to drawing 15A. The 20A receptacles are for equipment that REQUIRES a 20A receptacle to operate.
 
Z

z71sierraslt

Audioholic Intern
You will want to pay attention to how much power each piece of equipment draws. I would be looking at higher-sensitivity speakers, if possible.

I would also very much go for multiple subswoofers, and large ones too. The reason is it takes less power to produce bass with multiple subs- it's far more efficient. To get double the output from a single subwoofer, you need four times the power. For example, if your sub is using 10 watts to play at 90 dB and you want to double the SPL (in other words, you now want 96 dB), you need to increase the wattage to 40 watts. However, if you simply add a sub, that grants you an additional 6 dB for only half the power draw increase. Large subs are more sensitive than small subs, so a modest amount of wattage will go further with them. I would look at getting a couple of 15"s if it is in your budget.

Also look into good light control for your room, so you don't need a light cannon of a projector to get a good image. A good, bright screen can help here too, by giving you a nice vivid image without needing a ton of wattage going to the bulb.

I have my components set and I am upgrading my AVR and getting an AMP. After reading about power requirements for HT I got concerned and decided to check it out.

Yamaha RX-A3060
Outlaw 5000 (about 600 watts)
One 15" Sub (250 rms watts) 1000 peak
Sony Blu-Ray (24 watts)
BenQ projector (353 watts)
Klipsch Speakers (RC-62 II, RF-82 II, RS-52 II, RP-140SA Back surrounds, and 4 Yamaha ceiling speakers) so they are pretty efficient
Home theater powered seats(6) with sound shakers

Ceiling fan, no light control (keeping it simple)
digital clock

I think I should be ok. There are others with multiple subs and amps running on a 15a circuit
None of my components have 20amp prongs.

Is there anything else I need to be worried about?
 
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Pogre

Pogre

Audioholic Overlord
I would also very much go for multiple subswoofers, and large ones too. The reason is it takes less power to produce bass with multiple subs- it's far more efficient. To get double the output from a single subwoofer, you need four times the power. For example, if your sub is using 10 watts to play at 90 dB and you want to double the SPL (in other words, you now want 96 dB), you need to increase the wattage to 40 watts. However, if you simply add a sub, that grants you an additional 6db for only half the power draw increase.
Shady, wouldn't adding a sub give you 3db more output? Or am I confused on this one?

I couldn't agree more with getting two 15's and going big. Good subwoofage is often underrated. It can elevate your whole system. Everything sounds better.
 
mtrycrafts

mtrycrafts

Audioholic Slumlord
Shady, wouldn't adding a sub give you 3db more output? Or am I confused on this one?

I couldn't agree more with getting two 15's and going big. Good subwoofage is often underrated. It can elevate your whole system. Everything sounds better.
Doubling amp power on one driver gives you 3 dB. Two drivers with amps gives 6 dB. 2x power and 2x driver area.
 
Pogre

Pogre

Audioholic Overlord
Doubling amp power on one driver gives you 3 dB. Two drivers with amps gives 6 dB. 2x power and 2x driver area.
I just learned something! I did not know that. So yeah, even more reason to go with 2!
 
lovinthehd

lovinthehd

Audioholic Jedi
Wouldn't the subs need to be co-located to achieve 6dB?
 
S

shadyJ

Speaker of the House
Wouldn't the subs need to be co-located to achieve 6dB?
In theory, if the subs are within 1/4 of a wavelength of the frequency then the second will make a 6 dB contribution- but that is for an anechoic setting. Normal room conditions are much less predictable, because they are affected by boundary gain, pressure vessel gain, and phase differences, etc. Whatever the result is in-room, if you add a second sub, you double the amplitude capability of your system.
 
-Jim-

-Jim-

Full Audioholic
Folks,

The 20 amp receptacle doesn't limit the current to the device, the breaker in the panel does. This type of receptacle allows for flexibility in that you can plug in the "standard" 2 prong polarized plug (with or without the ground) which, by Code, is less than a 15 amp load. It will also allow you to plug a device that can pull 20 amps if it has the "T" type configuration.

What most folks forget is that if the 15 amp device malfunctions, and pulls up to 20 amps, the receptacle will deliver it regardless of plug type. In a standard circuit the breaker would limit the current to 15 amps.



And yes, I am a licenced Electrician...
 
WaynePflughaupt

WaynePflughaupt

Audioholic Samurai

FWIW there are some amps that have particular plugs that need an appropriate receptacle to take advantage of a 20A circuit, like this and this.
Yep...20 a = 12-2 wire, 15a = 14-2 wire.

The only reason to ever use the funny looking outlets on a 20amp circuit is if the appliance calls for it...you can have all 15a outlets on a 20a circuit if you want.
General information, FWIW: While it’s fine to have a 20-amp circuit with multiple standard (15 amp) outlets, as I understand, if you have a 20-amp appliance (i.e. with a 20-amp plug), it should have a dedicated circuit, meaning the only outlet on the circuit is a 20-amp device. Obviously if the appliance is a 20-amp load, there is no “room” for other devices to be plugged into the same circuit.

Regards,
Wayne A. Pflughaupt
 
mtrycrafts

mtrycrafts

Audioholic Slumlord


General information, FWIW: While it’s fine to have a 20-amp circuit with multiple standard (15 amp) outlets, as I understand, if you have a 20-amp appliance (i.e. with a 20-amp plug), it should have a dedicated circuit, meaning the only outlet on the circuit is a 20-amp device. Obviously if the appliance is a 20-amp load, there is no “room” for other devices to be plugged into the same circuit.

Regards,
Wayne A. Pflughaupt
That also makes sense.
 
Johnny2Bad

Johnny2Bad

Audioholic Chief
In the interest of answering the actual question asked:
On the back, near the AC inlet, of every single device in your home theatre is a label with the current draw in watts.

Add up the watts drawn by all of the devices in your home theatre. Alternately, add up the watts for only the devices you could, in a worst-case scenario, use at the same time.

Generally speaking, a 15A circuit should probably be limited to 13Amps, because a safety margin is ... well ... nice ... if fire is something you prefer to avoid.

But strictly speaking, assuming nothing ever fails, you could allow yourself to draw 15A provided there are no extension cords involved and the AC cords are kept reasonably short.

Assuming you live in the US or Canada, that's 13A times 120V = 1560 watts and 15A times 120V = 1800 watts *

If it's more than either of those figures (use the one based on how fire safe you want to be) you need a 20A circuit (at least). Or two 15A circuits, or some similar combination or arrangement.

The reason I bring up fire safety and a 2A (15-2 = 13A) safety margin, is because the circuit breaker that is supposed to keep you and your family safe has no idea how much power is being drawn by the devices plugged into the wall.

What it does have an idea of, is how much heat is being generated by your power usage. When it gets hot enough to (in theory) equate to more than 15A (or 20A, as the case may be) it trips.

Each time a breaker trips, it becomes somewhat less reliable. Breakers wear out if they are cycled a large number of times, to the point where they might not trip at the heat that corresponds with the amperage rating of the breaker.

Breakers also need a certain amount of time for the heat to build up. Brief demands may not trip it, even if the load exceeds the breaker's rating (15A, etc).

So, it is always good to remind yourself that if your gear, perhaps due to a failure, demands 20A or even 30A from the 15A circuit, the electrical system will do everything it can to supply that power, until the breaker trips. If the breaker doesn't trip, well, I suggest gathering up the children and getting out. That is, if you know it's happening, which you may easily not.

* Electric Utilities vary with regard to how much power they can send out and how regulated that power is. I know that in certain parts of North America 110V is common. Where I live, with no devices drawing from the circuit, I routinely measure 127V, which falls to somewhere between 117 and 122V if something is turned on and draws power on that circuit.

This affects how many watts your system can support. More voltage is better, to a point. Too much voltage can stress devices on the circuit, although it also might allow your amplifier to be able to put out more power. It's better to have a nice, steady 120V than either of the extremes.

** The above calculations for power draw are somewhat of a simplification, but do work well with Home Theatre devices. If you have a device that has a poor Power Factor ... Compact Fluorescent Lamps are notoriously bad ... they draw more power than what is actually printed on the label. But most people know not to use CFL bulbs on the same circuit as their Home Theatre or HiFi (LED lamps should also be avoided, they can introduce noise into the AC line). A good old low-wattage tungsten bulb lamp is best if you need supplemental lighting in your audio rack.
 
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Benni777

Benni777

Audioholic Intern
Folks,

The 20 amp receptacle doesn't limit the current to the device, the breaker in the panel does. This type of receptacle allows for flexibility in that you can plug in the "standard" 2 prong polarized plug (with or without the ground) which, by Code, is less than a 15 amp load. It will also allow you to plug a device that can pull 20 amps if it has the "T" type configuration.

What most folks forget is that if the 15 amp device malfunctions, and pulls up to 20 amps, the receptacle will deliver it regardless of plug type. In a standard circuit the breaker would limit the current to 15 amps.



And yes, I am a licenced Electrician...
Pm'd you
 
P

ParleyW

Junior Audioholic
Is a 20 Amp circuit enough to run a small home theater?
How much do you really need to run a small home theater?

Ex:
AVR 7.1.4 Surround
Amp (600 watt?)
Sub
Home Theater Seats
Blu-Ray Player
Projector
I picked up a Crestron 7x200 that requires a dedicated 20 amp circuit. My Panamax shows current draw assuming it’s accurate. I’ve really stomped on the volume that taxed my amp, sub amps etc. never pulled more than 5 amps.
 
Verdinut

Verdinut

Audioholic Ninja
I picked up a Crestron 7x200 that requires a dedicated 20 amp circuit. My Panamax shows current draw assuming it’s accurate. I’ve really stomped on the volume that taxed my amp, sub amps etc. never pulled more than 5 amps.
In a small home theater, the total current drawn is far less than 20 amps. The average power output to each speaker is only a couple of watts. Unless someone wants to play his HT at ear bleeding levels, even a 15 amp circuit should be sufficient.
If you don't drive your Crestron to a very high SPL, you should not even need a dedicated 20 amp circuit.
 
P

ParleyW

Junior Audioholic
In a small home theater, the total current drawn is far less than 20 amps. The average power output to each speaker is only a couple of watts. Unless someone wants to play his HT at ear bleeding levels, even a 15 amp circuit should be sufficient.
If you don't drive your Crestron to a very high SPL, you should not even need a dedicated 20 amp circuit.
I agree. I have a very large reference system, all 4 ohm. At insane levels, I’m seeing 3-4 amp draw. Kinda makes
Me sleep with one eye open with that Crestron. Doubles as a mig welder??
 
Pogre

Pogre

Audioholic Overlord
I agree. I have a very large reference system, all 4 ohm. At insane levels, I’m seeing 3-4 amp draw. Kinda makes
Me sleep with one eye open with that Crestron. Doubles as a mig welder??
Isn't that an ATI amp? I have a Monolith 7 on a 15 amp circuit and it has gobs of power too. Also ATI. Great amps.
 

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