Gordon Brockhouse talks to Sunfire’s Bob Carver (AMPLIFIERS)

[AcuDefTechGuy]

If those amps all put out their maximum wattage into any speakers you have all at once, the speakers would explode and your head would cave in, LOL

Pure American Muscle Horsepower, baby!

I guess the lightings, 4 pre-amps, & blu-ray player also produce power, right?
I wonder how much?
I've read that the pre-amplifiers have torroidal transformers power supplies?

 

[AcuDefTechGuy]

Unless your using the new math, 15A = 1800 watts, not 1440.
A 15A breaker trip at 1800 watts.

Also, I misspoke as to the bedroom on a 20A overcurrent device.
I meant to say "A bedroom should be on its own circuit."
Sorry for any added confusion.
My reasoning still stands, a TV, and a hair dryer in a bedroom, will trip a 15 amp breaker.

So each bedroom should have it's own 20A circuit. I'm guessing that with the TV, lights, 4 pre-amps, BD player, my max power should be no more than 8000 watts. So I would need a max of four 20A circuits for the HT?

Now I have a good idea of what I will need.

 

[AcuDefTechGuy]

You can generally figure how much power a given circuit using Ohm's law, or a derivative thereof.

P = I*V

where P = power, I = current and V = voltage

In the US, we have V = 120; I will be the amount of current allowed through your breaker, in this case, say, 15 amps.

Then,

P = I * V
P = 15*120 = 1,800 watts

Similarly, for a 20 A circuit, you can support (continuously, without blowing the breaker) 2,400 watts.

If they would just incorporate all this home theater into physics, students would retain the knowledge a lot better.

So that's why a 300 wpc x 7-ch amplifier requires one 20A circuit or two 15A circuits. Now I know.

 

[mtrycrafts]

Oh, No wonder my big microwave trips the circuit from time to time!

So is a 20A rated for like 2000 watts or more?

I noticed that each of the 15A circuit controls a few outlets, right? So if my HT room has 4 electrical outlets, but they are all controlled or shared by one circuit (all outlets in room go out when tripped), then my entire room is only rated for a max of 1440 watts? Yikes!

My Acurus amps: [300 wpc x 3 @ 4 ohms] x 4 = 3600 watts max
My DT built-in amps: 1800 watts + 1800 watts + 150 watts = 3750 watts
Total = 7350 watts on one 15A circuit?

As otto indicated, your breaker will break at 15A, 1800 watts. The circuit is calculated to 80% of its rated capacity for determining loads and number of circuits based on that 1440 watts to a 15A circuit. It will handle a hair dryer up to 1800 watts but code requires for such loads a 20A breaker because of that 80% factor.

Unless you are unlucky to have the first music disc needing max power at the same instant time and your volume is at reference level, you will almost never come even remotely close.

 

[Rickster71]

The 80% rule applies to known loads. (fixed equipment, fixed appliances)
There is no way of predicting what will be plugged into a receptacle in the future.
So for those, guessing at 80% ampacity would be impossible.

 

[AcuDefTechGuy]

The 80% rule applies to known loads. (fixed equipment, fixed appliances)
There is no way of predicting what will be plugged into a receptacle in the future.
So for those, guessing at 80% ampacity would be impossible.

Yeah, 20A is for me. Last Thanksgiving we used one of those table-top grills in the formal dinning room and it tripped the circuit! So for me, it seems like 15A is just not enough no matter which room and what application.

 

[mtrycrafts]

The 80% rule applies to known loads. (fixed equipment, fixed appliances)
There is no way of predicting what will be plugged into a receptacle in the future.
So for those, guessing at 80% ampacity would be impossible.

The number of minimum circuits are determined by by this rule and the square footage of the house. Homeowners don't know the rule but the more circuits, the less likelihood of overloads.
A circuit will blow at the designed limit no matter what. So will a 20A and the 30A breakers.

 

[Rickster71]

The number of minimum circuits are determined by by this rule and the square footage of the house. Homeowners don't know the rule but the more circuits, the less likelihood of overloads.A circuit will blow at the designed limit no matter what. So will a 20A and the 30A breakers.

You quoted the 80% rule, after you gave the incorrect load a 15amp breaker could supply.
(Go back and re-read your post #56)
Now your parroting whole house load calculations. Each time I bring up a point to explain why your incorrect, you go off on another tangent.

Also in this post, I made bold part of your quote, how your making two of my earlier points for me. (A bedroom should have it's own circuit) (There is no way of predicting what will be plugged into a receptacle in the future)

Look, I'm not interested in a flame war starting. Arguing semantics is such a waste of time, and gives me a headache.

 

[AcuDefTechGuy]

A circuit will blow at the designed limit no matter what. So will a 20A and the 30A breakers.

What? They have 30A outlets too? So that's 30A x 120V = 3600 watts MAX?

Since we never know what the future holds, it might be possible that I will go crazy one day and get four 1000-WPC amplifiers, those 30A circuits might come in handy.

 

[mtrycrafts]

What? They have 30A outlets too? So that's 30A x 120V = 3600 watts MAX?

Since we never know what the future holds, it might be possible that I will go crazy one day and get four 1000-WPC amplifiers, those 30A circuits might come in handy.

Oh, yes, central vacuum systems may use such a circuit. I have one

 

[AcuDefTechGuy]

Oh, yes, central vacuum systems may use such a circuit. I have one

So you have a 30A circuit in your house?

 

[OttoMatic]

Your oven and A/C probably run on 50A circuits (each on their own circuit). Open your breaker panel and see what's there!

 

[mtrycrafts]

Your oven and A/C probably run on 50A circuits (each on their own circuit). Open your breaker panel and see what's there!

And, they are 240V too Lots of power demand from those buggers

 

[mtrycrafts]

So you have a 30A circuit in your house?

Yes, one 30A-120V for the central vacc only.
As otto indicated, you may have bigger ones for other tasks but most likely they are 240V and the breakers are connected as they tie to both hot leads in the box.
Hair dryer on its own, kitchen has a good number of 20A for appliances.

If you are building or about to build, plan ahead, don't have them skimp on breakers, cat 5e cables, etc. Some cannot be anticipated

 

[OttoMatic]

Yes, one 30A-120V for the central vacc only.
As otto indicated, you may have bigger ones for other tasks but most likely they are 240V and the breakers are connected as they tie to both hot leads in the box.
Hair dryer on its own, kitchen has a good number of 20A for appliances.

If you are building or about to build, plan ahead, don't have them skimp on breakers, cat 5e cables, etc. Some cannot be anticipated

I would agree with both these. Yeah, you've got 240 V on some of these things. Lots of power available!

If I were building out new, I would definitely increase all this stuff. I mean, you probably don't really need 30A circuits in bedrooms, but I'd probably do the upgrade from 15A to 20A. In other rooms where there may eventually be even larger loads (basements, living rooms, etc.), I'd probably opt up as well -- multiple 20A circuits per room. Espeically if you have a target location for a HT or associated equipment.

I really have no idea how much more it would cost. The materials are a little more, and I know 12G cable is harder to deal with than 14G, so there will be more labor. And you might have to upgrade the whole electrical panel. But what's it gonna cost? An extra $2k? $5K?

In the long term, I think it'd be worth it.