[rcag_ils]

My Ultra 550 and Omega 240 has popped my 15A house breaker twice now, it's once in a blue moon event, and doesn't happen all the time, maybe once every three months or so. When this happened, there weren't much load on this breaker, just the preamp and the DAC.

 Has this happened to anyone?

[I.Greyhound Fan]

Are you sure that nothing else is on that circuit like an appliance, garage door opener or lights?  Amps can place a burden on circuits.  My Parasound draws 1300 watts.

[FullRangeMan]

Fortunately no. My apto had 5 circuit brakers:
50 A for shower, more two 30A and two 15A.

Take care, just one 15A breaker are prone to overload.

[rcag_ils]

Are you sure that nothing else is on that circuit like an appliance, garage door opener or lights?  Amps can place a burden on circuits.  My Parasound draws 1300 watts

Nothing else, no light was turned on, just a computer printer, preamp, CD player and the DAC, flipped the Ultra 550, or the Omega 240 power switch, "pop" everything went dark.

[Wayner]

Some circuit breakers are touchy. Every time one is tripped, the trip force required to trip it, lessens. This is why buying used circuit breakers is not always a good idea.

Because the amp naturally has a high inrush current load at turn-on, the stress from it on a "weaK" breaker will cause what is called nuisance tripping.

The possible cure is replacing the breaker.

Wayner

[rcag_ils]

I properly will replace it if it keeps tripping, Wayne. Just checked, the max breaker rating for Romex wire is 15A, so putting in a 20A is out of the question.

[WC]

Before you change the breaker to 20A you should verify that the wiring on that circuit is 12 GA wire. A 15A circuit is usually protecting a circuit wired with 14GA wire. The breaker is there to protect the wiring to prevent the wire from overloading and starting a fire.

[rcag_ils]

Before you change the breaker to 20A you should verify that the wiring on that circuit is 12 GA wire. A 15A circuit is usually protecting a circuit wired with 14GA wire. The breaker is there to protect the wiring to prevent the wire from overloading and starting a fire.

Thanks for the heads up, I am thinking in a regular house, they probably used 14GA wire.

[WC]

I properly will replace it if it keeps tripping, Wayne. Just checked, the max breaker rating for Romex wire is 15A, so putting in a 20A is out of the question.

12GA romex can handle 20A. 14GA romex would max out at 15A. Romex comes in both gauges of wire.

[rcag_ils]

Called the electrician, he indicated that the arc fault breaker maybe the problem, when the amp is turned on, it might have detected it as arcing occured, he recommend to replace it with a regular 15A, but no 20A.

[Wayner]

Good. As others have stated, stay with the 15A. There are several different classed of breakers within the 15A rating, all having to do with overload time. These are primarily used in industrial machine design, intended to stop nuisance tripping. The new breaker should fix the problem.

Wayner 

[trebejo]

Here, the breaker has broken when several nondescript appliances are on as well as the 550, and then the microwave or the a/c joins the party and after a few seconds, poof.

With no a/c or microwave, things are fine.

btw the 550 definitely dims the lights when it comes on, no matter who else is on. It lasts only an instant but it's clearly there. 

[Wayner]

120 volt branch circuits may have some trouble makers on line, that is for sure. Perhaps this speaks the possible pluses of having a dedicated circuit for such applications.

A 120 volt air conditioner by itself is not a good idea, as the amperage and wire gauge are all huge. Most are 240 volt.

My point is that because many appliances, along with Frank's amps, have high inrush current. It is always best to isolate these devises from each other (when possible) on other branch circuits. Obviously, that is not always feasible, so then minimize what can be a possible inrush current partner.

I'm sure that if you have a freezer and Frank's amp on the same circuit, that there is a possibility that at one time or another, they will both be put on at a relatively close time. Perhaps the sum of those 2 (or more) devices will trip the breaker. If one or the other can't be moved, then I suggest going with a different class breaker with a longer "hang" time for that particular circuit.

This is certainly an interesting subject/problem with several, if not expensive cures.

Wayner

[Tom Alverson]

Here is another possible explanation from http://www.powertransformer.us/toroidaltransformers.htm

Inrush Current Conditions

The excellent magnetic properties of the toroidal transformer and the high remanence of the grain-oriented silicon steel, occasionally leads to high inrush current at turn-on. This is true when the circuit is completed at the zero-crossing of the input voltage wave form.


In other words if you turn it off at just the right part of the AC cycle it can become partially magnetized.  If you then turn it back on at just the right (wrong) part of the AC cycle there will be a higher than usual inrush current.