Blew the breaker

[WaynerN]

Not exactly sure of the connection method you're describing, but it would seem that NEC 210.10 precludes connecting 15A or 20A receptacles to a 30A circuit.

There should be no problem. The breaker protects the wire between the breaker and the outlet, and the outlet type will restrain the current from the device. Having a lesser amperage outlet on a greater service offers no danger, as long as the outlet itself is not overloaded. That is controlled by the outlet type (and hense, its rating).

As an example, if one were to place a 20 amp outlet on a 15 amp circuit, the plugged in device could easily overload the wire ampacity and not trip the breaker. The outlet would not be damaged because it is rated for 20 amps. The wire may melt because it is not. The circuit breaker defends itself. If a 15 amp outlet is put on a 20 amp circuit, and a device that draws 15 amps is plugged in, the outlet is safe, because it is operating within its ampacity, the wire is safe because it too, is operating within its ampacity and the circuit breaker takes care of itself.

The circuit I propose could look something like this:
http://www.audiokarma.org/forums/attachment.php?attachmentid=483321&stc=1&d=1389815960


Wayner

 

[BayouTiger]

Well, obviously, there's a lot more that can fry with 30a available. It is very bad design practice to "just throw more horsepower at it". I don't think 30a is allowed for such use anyway as you mention.

 

[dusty42701]

...How many of you have a circuit (or 2) just for your system?

I have a 20A 120v and a 30A 240v.
That's for the pro system though. The circuit for everything except the amps is a 20A 120v, with 20A rec. (4 of them, 2 outlets in each quad.) and 12-2. This runs everything in the system other than the amps, sometimes I will add a buddy's computer to it for a lan party, maybe a ceramic heater too. It does just fine for that. Then there is the 30A 240v, run with an L6-30R and 10-2. This runs the amps.

 

[WaynerN]

Well, obviously, there's a lot more that can fry with 30a available. It is very bad design practice to "just throw more horsepower at it". I don't think 30a is allowed for such use anyway as you mention.

I have taken the NFPA-79e courses which deal with electrical safety. A 15 amp outlet in a short circuit can deliver 40,000amps for a few microseconds, that will melt everything. So 15 or 30 amps makes no difference as far as killing power goes. It takes only 8 milliamps of current (across the heart) to be fatal.

Wayner

PS, throwing more horsepower at it is exactly what you are doing (or proposing). I suggested to cut back on the throttle, if you go back to my first post. I personally think your power requirements are over the top, but that is what you want. I'm simply showing you a method to accomplish this. You need to consult your local, trusted electrician on this issue and maybe he has an even better idea for you.

Or you could go over to the Audiocircles and read the 3 pages of problems that that guy is having: http://www.audiocircle.com/index.php?topic=122494.0

 

[purple1]

Lets just figure what I need for the 4 amps.
Parasound 1000 watts
Acurus 1200 watts
Kenwood 350 watts
Kenwood 350 watts

Total = 2900 watts just for the power amps. I know this is max but lets just say I want to max it out.

Add 4 powered subs.

Now though in my plasma TV, preamp, tuner, vcr, cable box, blu-ray, dvd, laser disk, phono preamp and turntable.

Do you think I need more than one 15 amp circuit?

 

[WaynerN]

We need to know what the amp plates are for the sub-woofers. Then we need to add about 20% to take care of turn on transient current. Also would be nice to know if you have any sequential turn on power control. That will take out some power spikes at turn-on. What would be really bad is if all the amps turned on at once.

And at 2900 watts, your over 24 amps (2900/120 = 24.166 amps). That doesn't include the nasty turn on spike.

So I would pair up the parasound with one of the Kenwoods (1000+350=1350/120=11.25 amps, and acurus with the other Kenwood (1200+350 = 1550/120=12.91 amps.

Yeah, a 30 amp circuit may not cut it either. Looks like you are going to have to put 2 if not 3 circuits to this system. Come back with the sub info.

W

 

[whoaru99]

There should be no problem. The breaker protects the wire between the breaker and the outlet, and the outlet type will restrain the current from the device. Having a lesser amperage outlet on a greater service offers no danger, as long as the outlet itself is not overloaded. That is controlled by the outlet type (and hense, its rating).

As an example, if one were to place a 20 amp outlet on a 15 amp circuit, the plugged in device could easily overload the wire ampacity and not trip the breaker. The outlet would not be damaged because it is rated for 20 amps. The wire may melt because it is not. The circuit breaker defends itself. If a 15 amp outlet is put on a 20 amp circuit, and a device that draws 15 amps is plugged in, the outlet is safe, because it is operating within its ampacity, the wire is safe because it too, is operating within its ampacity and the circuit breaker takes care of itself.

The circuit I propose could look something like this:
http://www.audiokarma.org/forums/attachment.php?attachmentid=483321&stc=1&d=1389815960


Wayner

The problem is, as I mentioned previously, 15A or 20A receptacles on a 30A circuit seem to be a NEC code violation per 210.21. Excerpts attached.

210.21B1 seems to indicate that a single outlet may not have a rating less than the circuit rating.

210.21B3 says that 15A and 20A receptacles are limited to 20A circuits. In this case you can use a lower-rated (15A) receptacle on 20A circuit by specific NEC exception as long as there is more than one outlet on the circuit. A duplex receptacle counts as two so you can do it.

The problem I think that's being overlooked in your position is that small loads on big circuits can be a problem. Not because of the load they present is too much and not because the house wiring circuit, per se, is at risk.

The risk, and what I think the NEC is trying to prevent with these limits, is small loads tend to have small cords. Small cords may not be able to safely survive the fault current of a big circuit.

 

[BayouTiger]

I have taken the NFPA-79e courses which deal with electrical safety. A 15 amp outlet in a short circuit can deliver 40,000amps for a few microseconds, that will melt everything. So 15 or 30 amps makes no difference as far as killing power goes. It takes only 8 milliamps of current (across the heart) to be fatal.

Wayner

PS, throwing more horsepower at it is exactly what you are doing (or proposing). I suggested to cut back on the throttle, if you go back to my first post. I personally think your power requirements are over the top, but that is what you want. I'm simply showing you a method to accomplish this. You need to consult your local, trusted electrician on this issue and maybe he has an even better idea for you.

Or you could go over to the Audiocircles and read the 3 pages of problems that that guy is having: http://www.audiocircle.com/index.php?topic=122494.0

Well, actually we could get into a discussion about SCCR and available current and such, but it wouldn't help the OP! It only takes a few feet of #12 wire to bleed off the available current so that's not really the issue, I am more worried about how much damage can be done to equipment before a 30a breaker will trip if he had a problem. I'm pretty well versed in the safety side of it as well.

I am wondering is he might be using an old breaker as the bi-metal can cause an old breaker to trip earlier than it should. We use fully magnetic breakers in the theatrical lighting business as they are less prone to nuisance tripping caused by very short inrush currents than thermo-magnetic, but that's not an option for a homeowner.

More reason I recommended he get a plug load meter and see what is actually going on.

 

[whoaru99]

Bear in mind the premises breakers (and NEC in general) aren't there to protect the devices. They're there, ultimately, to protect you.

 

[purple1]

I am wondering is he might be using an old breaker as the bi-metal can cause an old breaker to trip earlier than it should. We use fully magnetic breakers in the theatrical lighting business as they are less prone to nuisance tripping caused by very short inrush currents than thermo-magnetic, but that's not an option for a homeowner.

Brand new Square D QO breaker.

 

[purple1]

Thanks for the info everyone. I'm going to upgrade the one outlet to 20 amps and add a second outlet also at 20 amps. If I have problems after that we can talk about what else I could do. I'm removing one breaker and replacing it, but I only have one space left in the box and the second breaker is going to fill it.

 

[BayouTiger]

That's a good one! I hope to replace all mine at home with those soon!

I am still thinking that one of your pieces has a big inrush hitting you. Is the breaker warm when it trips? cause that can cause them to trip early as well.

 

[purple1]

That's a good one! I hope to replace all mine at home with those soon!

I am still thinking that one of your pieces has a big inrush hitting you. Is the breaker warm when it trips? cause that can cause them to trip early as well.

We had been playing music for about an hour when I deciced to crank it up. Thats when the breaker poped. I don't have any trouble if I don't crank it.

 

[whoaru99]

Thanks for the info everyone. I'm going to upgrade the one outlet to 20 amps and add a second outlet also at 20 amps. If I have problems after that we can talk about what else I could do. I'm removing one breaker and replacing it, but I only have one space left in the box and the second breaker is going to fill it.

I don't think you're going to have a problem as long as you spread out the loads. You're increasing your capacity by 2.67x.

The main concerns are the amps and subs. The plasma probably is 300 watts, give or take, all that other stuff...DVD player, cable box, etc. doesn't amount to much.

 

[powerman]

Thanks for the info everyone. I'm going to upgrade the one outlet to 20 amps and add a second outlet also at 20 amps. If I have problems after that we can talk about what else I could do. I'm removing one breaker and replacing it, but I only have one space left in the box and the second breaker is going to fill it.

That's the best thing to do. I have 5 dedicated 20 amp curcuits in my listening room and wish I could have more. :thmbsp: