AVS Forum banner
1 - 20 of 30 Posts

·
Registered
Joined
·
896 Posts
Discussion Starter · #1 ·
I have one dedicated regular circuit to the fuse box for my gear. I have two power bars rated at 1800 watts each with 17 devices plugged into the two wall outlets including a three channel 200 watt and a two channel 200 watt amp in addition to a remote amp for the second zone.


I have been reading about power clipping with certain power conditioners.


Question, is this too many devices for one outlet?


Question, what is the maximum rating for one regular (15 amp, I think) curcuit?


Question, if it is too many can I change the circuit to a 30 amp?


Question, should I run another 15 amp line or what? How do I know when it is too much?
 

·
Registered
Joined
·
2,205 Posts
Question, is this too many devices for one outlet?


The issue is not the number of devices nor the power output rating of your amps, but the total demand. To determine the load you add the power consumption ratings of each piece of equipment.


Question, what is the maximum rating for one regular (15 amp, I think) circuit?

1800 watts Circuit capacity is figured by multiplying the nominal voltage times the currant. A 15 ampere breaker allows a current of up to 15 amps. So 120 V x 15 = 1800 watts. You can plug in any number of devices so long as the total demand at any moment does not exceed 1800 watts.


Question, if it is too many can I change the circuit to a 30 amp?

No. You may not have a circuit larger than 20 amps for small appliances or 15 amps for other general use. You may have a 20amp circuit with 15 amp receptacles however.

20 amp circuits require 12 AWG wire and 15 amp circuits are not smaller than 14AWG. You may wire a 15 amp circuit with number 12 wire (it may be required in some locations or needed to reduce voltage drop in long runs) but are limited to 15 amp receptacles.


Question, should I run another 15 amp line or what? How do I know when it is too much?

If you need more power you can replace your 15 amp circuit with a 20 amp circuit or add a second circuit of 15 or 20 amps. Calculating your load will tell you what you need.
 

·
Registered
Joined
·
896 Posts
Discussion Starter · #4 ·

Quote:
Question, is this too many devices for one outlet?


The issue is not the number of devices nor the power output rating of your amps, but the total demand. To determine the load you add the power consumption ratings of each piece of equipment.

Some devices do not have a rating only a maximum rating which I believe is for the fuse? But if I assume that it is the power rating then I simply add them all up and if they do not exceed 1800 watts for both recptacles on the one circuit I am O.K. correct? The two amps alone have 1000 and 800 watts maximum printed on them. So if that is the rating and not the fuse then just those two things alone are enough for the entire circuit then.



Quote:
Question, what is the maximum rating for one regular (15 amp, I think) circuit?


1800 watts Circuit capacity is figured by multiplying the nominal voltage times the currant. A 15 ampere breaker allows a current of up to 15 amps. So 120 V x 15 = 1800 watts. You can plug in any number of devices so long as the total demand at any moment does not exceed 1800 watts.

Is that for the entire circuit or one outlet of two outlet receptacle?

Quote:
Question, should I run another 15 amp line or what? How do I know when it is too much?


If you need more power you can replace your 15 amp circuit with a 20 amp circuit or add a second circuit of 15 or 20 amps. Calculating your load will tell you what you need

.


I have read that all devices should be plugged into the same outlet to reduce ground noise problems. I have also experienced it and if I run a second line that could cause this problem.


Thanks for the reply I will check the wiring to see if what awg it is maybe I can just change the breaker to a 20 amp if needed.
 

·
Registered
Joined
·
44 Posts
20 amp is the largest CB you can use with standard plugs, however the wiring will need to be changed if you choose this route. Do not just put a bigger breaker in the panel as this could create a fire hazard that insurance would not cover if something bad happened. Maximum current is more a function of wire gage than plug size or breaker capacity; wires are what get hot and cause the insulation to catch fire.

To meet code and your specific requirements you should really hire an electrician or licenced contractor to recommend a dedicated circuit(s) for your gear.


I don't understand what you mean by (2) 1800 watt power bars, but if they're both on a common standard circuit, then you only have 1800 watts available to power them both (read about 900 each). At full load, which is HIGHLY unlikely for normal listening, your two amps alone could draw aboubt 2100 watts from the wall. Remember that AB amplifiers are about 50% efficient and you're probably running around 95% power factor (don't ask). So the full continuous 200 watts / channel will cost about 420 watts from the wall to generate.


If you choose to run an additional 15 amp circuit this is fine as long as you don't mind pulling the wire from the box to your room. Also be careful when installing breakers as you can easily get electrocuted if you don't know exactly what you're doing.


As for average load on the circuit, you've got two options. Buy a power condition that has voltage and current meters on it; plug all your devices into this and then watch the meters. Option two is to buy a clamp on meter and read the current draw at the outlet, you can't do this by simply placing the clamp around an extension cord, you need to clamp around the "hot" or black conductor only.
 

·
Registered
Joined
·
44 Posts

Quote:
Originally Posted by kiwi2000 /forum/post/0


I had an electrician run a dedicated line my question now is, is it enough?


So you have 1 new dedicated 15A outlet and one normal shared outlet that was the original outlet in the room? If so, this should be OK.


Again, you'll never run peak power all the time so you should be OK with even a single 15A circuit, but 2 circuits is always better.
 

·
Registered
Joined
·
6,946 Posts

Quote:
Originally Posted by kiwi2000 /forum/post/0


I had an electrician run a dedicated line my question now is, is it enough?

A simple answer and a more complex answer have already been given.


Simple = the breaker is not tripping = adequate capacity.


Complex = measure the voltage sag and or voltage drop and the current to see how close you are.


A 15A circuit can deliver much more than 15A for short periods to cover momentary peak demands so that 1800 watt rating is a bit misleading when it comes to audio playback. Few of us ever play our systems with full continuous output on all channels driven as is often calculated in these scenarios.
 

·
Registered
Joined
·
130 Posts
this is a good thread... i've been trying to figure out how to wire my new office / HT...


i will have 5 recepticles, and was wondeing if i could throw them all on one 15A breaker, or do 2, and split the room and the 4 overhead recessed lights between them, incase of a power surge that trips the circuit i'll still have 2 overhead lights to see what i'm doing...
 

·
Registered
Joined
·
44 Posts

Quote:
Originally Posted by ImDiesel /forum/post/0


this is a good thread... i've been trying to figure out how to wire my new office / HT...


i will have 5 recepticles, and was wondeing if i could throw them all on one 15A breaker, or do 2, and split the room and the 4 overhead recessed lights between them, incase of a power surge that trips the circuit i'll still have 2 overhead lights to see what i'm doing...

I'd say two circuits; one for the HT stuff only and a separate one for the office stuff. I assume you'll be using a computer in the office, computers can produce quite a bit of noise and put this back into the AC line (run a vacuum cleaner on the same circuit as your TV and look what happens to the picture).
 

·
Registered
Joined
·
2,328 Posts

Quote:
Originally Posted by trekguy /forum/post/0


1800 watts Circuit capacity is figured by multiplying the nominal voltage times the currant. A 15 ampere breaker allows a current of up to 15 amps. So 120 V x 15 = 1800 watts. You can plug in any number of devices so long as the total demand at any moment does not exceed 1800 watts.


[/i]

You should also remain below 80% of the breaker rating to ensure ongoing proper operation. A load of 16A on a 20A breaker is a good rule of thumb.
 

·
Registered
Joined
·
2,205 Posts
Things change but I believe that the 80% rule applies to continuous loads of 3 hrs or more, unless the breaker is rated for 100% duty.


Thus I think that the rule of thumb I gave is good for sizing a circuit, even though none of the typical home theater equipment will draw the power stated on the chassis on a continuous basis. Breakers as already noted have significant short term over current limits, to allow for heavy momentary loads such as an induction motor starting. Still I believe that typically circuit demand is calculated on the rated device draw, and breakers and wire sized accordingly.
 

·
Registered
Joined
·
2,328 Posts

Quote:
Originally Posted by trekguy /forum/post/0


Things change but I believe that the 80% rule applies to continuous loads of 3 hrs or more, unless the breaker is rated for 100% duty.


Thus I think that the rule of thumb I gave is good for sizing a circuit, even though none of the typical home theater equipment will draw the power stated on the chassis on a continuous basis. Breakers as already noted have significant short term over current limits, to allow for heavy momentary loads such as an induction motor starting. Still I believe that typically circuit demand is calculated on the rated device draw, and breakers and wire sized accordingly.

I work in the power system testing business. We see overloaded breakers on a daily basis. The breakers we are discussing are cheap garbage with very poor tolerances ($3-6 each). The contacts will and do heat up nicely with loading near 100% and since the tolerance is generally poor, there is no guarantee that the thermal element will not pick up because of the overheating contacts. Tis better to err on the side of caution. Besides, how many people track all of the loads they add to a circuit...parasitic loads anyone?


When we provide engineering for industrial and commercial facilities we plan for loading of no more than 80%....and these breakers are much better than the crap we use for residential panels.
 

·
Registered
Joined
·
2,415 Posts

Quote:
Originally Posted by AV Doogie /forum/post/0


When we provide engineering for industrial and commercial facilities we plan for loading of no more than 80%....and these breakers are much better than the crap we use for residential panels.

He's right. On top of that, [email protected] yields 1800VA, not 1800W. You have to take the power factor into account; at a .8 power factor, you would only be able to get 1440W out of a 15A/120VAC circuit.


For the guy who said you're not overloaded until the circuit breaker trips, this is VERY poor advice. You can suffer from voltage sags severe enough to impact your equipment at levels well below those necessary to trip the breaker. The length of the wiring run has a lot to do with this - the breaker makes a lousy load meter.


To be safe, assume an 80% load safety factor along with a .85 power factor (reasonable for consumer electronics with switching power supplies). This yields around a ~.7 loading limit. For a 15A circuit, you should not plan for more than 10-11 A; 14A should be the design limit for a 20A circuit. [For a purely linear or resistive load, you don't need the power factor multiplier, but PCs, printers, displays, etc., don't generally operate at unity power factor.]
 

·
Registered
Joined
·
2,205 Posts
Ok VA is not the same as watts, and non resistive loads have power factors (I have not entirely forgot everything from HS physics) and an 80% figure allows for turning on the waffle iron. I will of course defer to your current commercial knowledge. Except for one but.


If one adds up the rated watts or volt-amperes or amperes of each piece of HT equipment, what is the likely actual load? Even if it adds up to 1800, it will in fact be a much smaller number, way under 1800.


My plasma has a rated max power draw of 535 watts. My AVR has a rated draw of 8.1 amps (972 VA). My DVD player uses 17 watts. The sub is rated at 750 watts.

535+972+17+750= 2328 VA or a current of 19.4 A. Now let's see with a PF of .85 2328/(120X.85) = 22.82 A. But wait I forgot room lights and the DVR.


In use the plasma draws closer to 200 to 250 watts. The AVR is drawing somewhere between say 30 to 100 watts. My sub the same. Let's put in another 100 for other stuff. 250+100+100+17+100=567 VA or 4.25 A. At a .85PF the current is 5.6 A.


So I concede that you guys are correct, one should allow for PF and a prudent margin for expansion, etc. My rule of thumb is actually too conservative.
 

·
Registered
Joined
·
896 Posts
Discussion Starter · #16 ·

Quote:
Originally Posted by bryan.carlson /forum/post/0


So you have 1 new dedicated 15A outlet and one normal shared outlet that was the original outlet in the room? If so, this should be OK.


Again, you'll never run peak power all the time so you should be OK with even a single 15A circuit, but 2 circuits is always better.


I did not mention this in the posting but yes I do have an original outlet in addition to the dedicated outlet. The 1000 watts maximum and 800 watts maximum is the max amount that the amps could draw correct? That means that they should be on thier own circuit and all other devices on another circuit or I could have had a 30 amp put in in the first place.


I did hire a licensed electrician and went by his recomendation. When it was installed I did not have the luxury of the knowledge base that this forum offers.


1. I could use the second original outlet and possibly introduce ground issues because who knows what else is on that circuit.


2. Purchase a power conditioner with a voltage meter.


3. Leave it as it is as members are correct in stating that the beaker has not tripped so the maximum rating must not have been exceeded.


I shall opt for number 2 and monitor the voltage but not all devices will be able to be connected unless I piggy back one 10 outlet power bar on the new 10 outlet bar.
 

·
Registered
Joined
·
6,946 Posts
Here's a really simple question.


What about your "current" power situation leads you to believe it's inadequate?


Personally, I think it's much ado about a problem that doesn't exist - except the part about having to piggyback power strips. I've done it, but don't like doing it, and can't identify any particular problem it's caused.
 

·
Registered
Joined
·
896 Posts
Discussion Starter · #18 ·
What got me going was areview I read in "widescreen review" issue 105 about a furman power conditioner. In it the reviewer speaks about his circuit to the theater.


He writes " the harder I pushed the system, volume wise, the easier it was to hear signs of current limiting. Dynamics would soften. I had stacked the deck against the furman rated at a nominal 1800 watts output, and I connected 1550 ouput watts of amplification and 700 watts of source components. Considering the amps could draw 2500 to 3000 watts at loud listening levels."


It is a long article what got me thinking is I have paid much for pristine sound and video. What if it is being limited by current line voltage?
 

·
Registered
Joined
·
23,414 Posts

Quote:
Originally Posted by kiwi2000 /forum/post/0


It is a long article what got me thinking is I have paid much for pristine sound and video. What if it is being limited by current line voltage?

IMO... don't always believe what you read. Secondly, if you don't "hear" or have a problem, sit back and enjoy.


OTOH... you can always get an eletrical contractor out to install a dedicated 20amp circuit (or two) and also add a power conditioner for a few hundred bucks for peace of mind.
 
1 - 20 of 30 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top