[Tyreman]

Currently have 2-15 amp dedicated lines for home theater.

One 15 amp line has the 3- 3B ST Brystons and Panasonic Plasma TV on it.
(All have 3 wire grounded plugs no hums no fuss, dead quiet)

Other 15 amp line has the Yamaha Receiver RX-V1075 used as a preamp for the Brystons and Rogers cable box.
(polarized plugs on each of these)So not much load on this line.

Being an HVAC tech I have used a fluke amp meter and find never draws that much on the amp line circuit... even when Plasma TV is on.
Listen to fair bit of FM.

EDIT: cable coax comes into cable box directly, inline VRD-1FF  Jensen filter ahead of it.
          cable box connection to receiver is with Belden HDMI cable
          cable box connection from receiver to TV is with Belden HDMI cable
 
I have learned by testing when I move any of the amps or TV(3 wire grounded plugs) over to the dedicated line for the Yamaha receiver and  rogers cable box.... hum comes.
Leave well enough alone or add another 15 amp line.

[Phil A]

Somewhat dependent on the load (impedance, how loud you listen) that each amp drives and the circuit breakers (are they the newer arc fault ones?), however, each 15 amp circuit can handle 1800W of consumption.  Good chance the hum is the cable box (the 3BST I have has a ground switch on the back - have you tried that?).  I'd be wary of 3 amps plus a plasma TV on one circuit.

[Tyreman]

The circuit breakers are traditional FPE 15 amp ones.
NOT arc fault ones or gfci's

Yeah I thought hum was cable box to.
Had them ground coax properly and added jensen inline transformer on the coax line.

I can try the ground lift switch.

[Tyreman]

Was able to balance out equipment on both 15amp separate ac lines without ground loop hum
All good.

[Phil A]

Was able to balance out equipment on both 15amp separate ac lines without ground loop hum
All good.

Congrats, enjoy.  I have a 3BST in a secondary system (which I  got used as I needed an amp of shallow depth to sit behind a display and struggled until I got one - was really sorry as I had gotten PowerPAC (120) monoblocks used several years before and played with them before selling them for a drop more than I bought them for as I could not foresee a use for them - big mistake as several months later I was kicking myself)

[Wayner]

The problem with having 2 high power amps on one line is not their operating condition, but rather the enormous turn-on spike they will have on the breaker if both are turned on at the same time. This can usually be offset by having one amp on a delay turn-on.

For a while, I had two Sunfire, 2 channel amps on one 20 amp circuit, but did not have any way to turn them on separately and at different times. I always tripped the breaker. (So I had one on delay turn on, the other I plugged the cord into the IEC outlet, as these amps did not have an "on" switch). PITA.

Wayner

[Phil A]

I even had a problem (I have arc fault breakers) with one 3-channel amp on a receptacle on its own 15 amp circuit.  It would trip half the time upon turn on.  If I ran a long extension could to a receptacle which along with other ones was on a 20 amp circuit, it was fine.  I have a 20 amp circuit (for the Torus RM20) for the main system and two receptacles each on their own 15 amp circuit.  I tried a bunch of things and then just opted to sell the 3-channel amp in favor of a class D monoblock for the center channel and it's fine now.  Plasma TV power consumption, unlike LCD or DLP which run at a constant power level, varies with program material and could have periods when they are using a decent percentage of the available power consumption on the circuit, and, depending on the load on the amps and other conditions with the power itself certainly could cause a circuit trip with enough consumption on the line.

[Phil A]

Here's a little comparison of consumption on TV types - http://en.wikipedia.org/wiki/Comparison_of_CRT,_LCD,_Plasma,_and_OLED

[Phil A]

This is the rated power consumption of a lower power (than the 3BST) Bryston amp - http://www.audioadvisor.com/prodinfo.asp?number=BY2BLP
"Stereo 8 Ohms (50W ea.), 286W; Stereo 4 Ohms (100W ea.) 498W"
So, as noted in my original response (depending on impedance and how loud one listens), having three amps and the plasma on on circuit can cause an issue.

[BrystonFan]

Thanks Phil A - you always provide good insight and useful links!
My BIT-20, I have everything running thru it - never a trip.
4BSST2, 9BSST, SP3, BCD-1, Oppo105, PS3, digitalpvr, dvr, velodyne dd12, 60" led tv.

[Phil A]

Thanks Phil A - you always provide good insight and useful links!
My BIT-20, I have everything running thru it - never a trip.
4BSST2, 9BSST, SP3, BCD-1, Oppo105, PS3, digitalpvr, dvr, velodyne dd12, 60" led tv.

Thanks, a 20 amp circuit can handle 2400 Watts.  Really a nice collection of equipment you have. I have one big amp plugged into my RM20 with a bunch of other things.  I have an integrated AV system with a 2-channel preamp with HT Bypass so I have the Class D amp in its own 15 amp circuit and then I have the receiver in another dedicated circuit and some other things plugged into other circuits.  In an old house I had my 3BST in the basement system (driving height channels - tried to plug it into a circuit near the main components to drive the left and right channel but it just would shut right off as there was too much on the circuit and that's why I went with the 20 amp and two 15 amp extra circuits in my current main system).