Star grounded and it still hums!!!!

Aren't outlets with an isolated ground orange or plain with an orange triangle? In the photo the quad outlet that is supposed to have an isolated ground looked like a regular outlet. John K.

That would certainly be an easy fix...can anyone confirm this to be true? Ross

Don't wate your time changing dimmers only to find out they might not change anything. If the dimmers are turned off or on 100% they should have no effect on noise/emf. just start with all the dimmers off, do you still have noise problems? My guess is yes, in wich case you can eliminate the dimmers, or at least confirm that they aren't the major source of noise. Start by fixing your ground problem. You must have all your grounds bonded at one point in the main panel, no exceptions, this is also where the neutral connects to the ground system. My guess is that you are getting a voltage potential between the isolated grounds and the main ground/neutral system causing noise and/or ground loop problems. What you have is essentially a ground loop consisting of 50 odd feet of you main ground/neutral system 30 or so odd feet of earth and then anouther 20 or so feet of ig wire :shock: :shock: It should be no surprise that you have a noise problem. As an example if you were to drive two stakes into the ground spaced apart anywhere in the world you could measure a voltage between the two. Your ground and neutral system must connect to the same ground rod system otherwise this voltage potential can exist along with induced noise. For something interesting take a look at a typical schematic of a guitar amp. Notice that the sheild side of the guitar cable IOW what connects to the strings/pickups etc, is directly connected to the house electrical ground :shock: :shock: :shock: Now imagine that for a moment, considering how sensitive guitars are to emf, that what you have done is run a direct line from you guitar, via the house wiring through many feet of wire into a 6 foot stake drivin into the earth :shock: :shock: Normally this would connect to the neutral system and everything would be at the same potential thus eliminating noise and safety hazards. Did I say already that what you have is a safety hazard? Not trying to harp on you to hard, I just don't want you chasing something that isn't going to fix your problem, along with the safety issue. If your sceptical of my advice you could try an easy temporary fix. Run a 12/14 guage wire connecting your isolated grounds to your regular grounds in the sub box. If the noise goes away you know what you gotta do. PS I had a studio with a dimmer on seperate circut from the other wiring, didn't have any effect on noise in the studio other than maybe if I stuck a guitar right up to it or the light. Read what lunatic says too BTW. Maybe lunatic or others can confirm this but I think that if you connected your IG buss in you sub panel to the regular ground buss in the sub panel with the prober guage wire and removed the connection to the sub panel ground rod I think you'd be to code.

I appreciate everyones input and guidance. My challenge is most electricians want to wire stuff up without considering what I am trying to accomplish with the audio. As a result, I have an electrician that read posts from this forum that I printed prior to him doing the work who obviously didn't understand...so he got wrong. Just this past Tuesday I brought in the right guy for the job...he was hard to find...and understand exactly what we need to do. Thanks for all of the advice and PATIENCE! I will post results and let everyone know how it turns out. Ross

Just curious... did you get this worked out? What was the solution and end result? Please update us so future readers can learn, learn, learn :D

Almost there...I will report back within the next week or so with the outcome. Ross

Eriksmusicproduction wrote:

Start by fixing your ground problem. You must have all your grounds bonded at one point in the main panel, no exceptions, this is also where the neutral connects to the ground system. My guess is that you are getting a voltage potential between the isolated grounds and the main ground/neutral system causing noise and/or ground loop problems.

OK...case closed. Ground Problem just as described above and other members had suggested. I hired a master electrician and former county inspector to look at my problem. He immediately saw the problem and began to curse me and the electrician who first did the work. First lesson that if anyone is to read this post in the future should know, is not all electricians are created equally...even if they have been electricians for twenty years and worked large commercial projects. Second lesson, is READ THE THREAD ABOUT GETTING PERMITS AND INSPECTIONS...now go read it again. Yes it's a pain in the ass but the inspection process protects you from potentially huge liabilities. The electrician gave me a few pointers. -Remove the carpet from my studio and go hard wood floors. The berber carpet causes static electricity so he said in the meantime, stand on a neoprene mat. -Remove the plastic mat I have under my studio chair as it also transfers static electricity from the rug, through the chair, into me, where I then touch gear and routinely get a little "shock". -He cut the line running to the dedicated ground rods coming from the sub panel and hooked my sub panel that has all of the star grounded outlets to the ground going to the main house panel so I now have one common ground for the entire electrical system of both the studio and the house. Turned it all back on...fired up an amp and turned it all the way to 11 and it was quite as a church mouse :) Turned on the dimmers and it started buzzing like a mutha... ...Now that I am grounded proper and no longer in danger of electrocuting myself, I'll go back and request feedback on my original thread about dimmers :lol: Thanks for all the help!!! Ross

Glad to hear your finally noise free. And safe :) Hopefully this thread will help others avoid similar situations. Shouldn't there be a sticky outlining the proper way to star ground a system? I've read probably all the threads here relating to star grounds and there is a lot of discrepencies. If you were me you'd replace all dimmers with switches and find the wattage of bulbs that give you the amount of light you need. That's what I did, alot cheaper than variacs.