Adding a new 20Amp outlet for my amp

also be sure to verify the line connection polarity: that hot is hot and neutral is neutral

Don't tell the electrician... show him.

If he has no clue of what to do to fix that, get another electrician.

of the best paths to follow, apart and along with the above posts, try to eleiminate the loop yourself. Tons of info here on how to do that very thing... and I've posted to them till I'm blue so search for ground loops and go from there.

The primary sources are cable boxes, and satellite boxes. Sometimes phone systems that use a DC power sup backup too.

OK.. just flip off all breakers except for the ones supplying the audio gear. turn them on one at a time and check for the buzz.

if with all the ckts off at the breaker panel save for the audio and you still get the buzz... lift the cable ground. Wait 15 min or so and check it.

If the buzz is still going with all ckts off but the stereo system ckts, and the outside cable box ground is lifted, it's one of two things.... it's one of the pieces attached to those ckts feeding the stereo, OR... as was/is my own case... check the inside of the breaker panel and see if your ground bus and neutral bus are tied together.

In some areas, this is code. So fi they are and the electricain OKs it... I've found only one other solution.... well two, but only one cheap one.

Cheap one:
Lift the ground wire from the outlets feeding the gear.

Mo' 'spensive one:
Transformers. Isolation transformers specifically for the dedicated ckts. this is a boon too for the system as it aids to a lower noise floor. A dedicated ground wire other than your service ground can them gbe used.

It's a simple enough thing to do, and the aprts aren't the costly things, it'll be the labor to put them in that will hurt more.

I lifted the grounds on every ded ckt except the one I use for the preamp & Processor. I also used 'cheater plugs' on verious appliances using 110v, dishwasher, fridge, and WM.... but that's me.

Ground loop is a condition where an unintended connection to ground is made through an interfering electrical conductor. Generally ground loop connection exists when an electrical system is connected through more than one way to the electrical ground.

When two or more devices are connected to a common ground through different paths, a ground loop occurs. Currents flow through these multiple paths and develop voltages which can cause damage, noise or 50Hz/60Hz hum in audio or video equipment. To prevent ground loops, all signal grounds need to go to one common point and when two grounding points cannot be avoided, one side must isolate the signal and grounds from the other.

The bottom line is that a perfect "quiet" ground does not exist. The basics of all noise problems on the grounding system boils down to what is objectionable current. With the exception of hospital systems, the definition is vague at best. The standard electrical grounding system throughout the building isn't designed to have current constantly flowing through it--and yet it does, you cannot stop it. The reason a ground will not and never be perfectly noise free is that the grounding electrode conductor is nothing more than a long wire from point A to point B. And the longer the wire the more noise it will pick up.

Very good advice from Stan already. I'd just like to add that you should run all circuits from the same leg of your service entrance. This avoids a combination which could yield 240V.

Either run 2 separate (minimum) lines directly from the S.E. panel or install a sub panel beneath your listening area and run lines from there.

Good luck and enjoy.

Have at least 2 done at the same time and get some good quality boxes. I use FIM, which I sell, but there are many good ones, Oayide, PS, etc. While these may vary in sound ANY of them represent a huge jump over hardware store boxes. Use 12 gauge wire at minimum. I haven't had any problems with my two lines, put the amp on one of them and everything else on the other and see if this doesn't improve the sound. There are other configurations, play around to see which works the best. I have found that the BPT multiple outlet boxes work very well, I have no connection to them.