Star grounded and it still hums!!!!

Post by **Aaronw** » Wed Jan 31, 2007 12:59 am

I think I already see a potential problem. All your house grounds and neutrals are all on the same bus. Is there any way you can separate them?

Eriksmusicproduction · Wed Jan 31, 2007 2:28 pm

"think I already see a potential problem. All your house grounds and neutrals are all on the same bus. Is there any way you can separate them?"

I'm not sure I understand your logic. Seperating them at the main panel would make the entire house wiring unsafe and do nothing for the studio wiring as the star point is at the sub panel.

Eriksmusicproduction · Wed Jan 31, 2007 2:36 pm

"think I already see a potential problem. All your house grounds and neutrals are all on the same bus. Is there any way you can separate them?"

I'm not sure I understand your logic. Seperating them at the main panel would make the entire house wiring unsafe and do nothing for the studio wiring as the star point is at the sub panel.

Post by **Aaronw** » Wed Jan 31, 2007 3:22 pm

From the looks of it, it looks like your neutral and ground are the same thing in the panel. What I meant by it, was the neutral should be grounded by the power company...correct? As well as a ground for the ground perhaps?

I'm going off of some other info another tech gave me a few weeks ago about "tech Power".

Check something for me...do you have meter? Measure the voltage between "Neutral" and "Ground". Also the voltages between the hot legs and Neutral and the hot legs and Ground. Post your results.

Also while your at it, either unplug stuff in the house or switch your breakers and see if any of that quiets it down.

Post by **Aaronw** » Wed Jan 31, 2007 3:22 pm

From the looks of it, it looks like your neutral and ground are the same thing in the panel. What I meant by it, was the neutral should be grounded by the power company...correct? As well as a ground for the ground perhaps?

I'm going off of some other info another tech gave me a few weeks ago about "tech Power".

Check something for me...do you have meter? Measure the voltage between "Neutral" and "Ground". Also the voltages between the hot legs and Neutral and the hot legs and Ground. Post your results.

Also while your at it, either unplug stuff in the house or switch your breakers and see if any of that quiets it down.

lunatic · Post by **lunatic** » Sun Feb 18, 2007 10:36 am

Hey Guys,

I just saw this and thought I'd post some thoughts. You guys probably already know this and I apologize of you do. Just tryin' to help out...

At your service entrance (i.e. main panel for the house) the neutral and ground are bonded together. This isn't necessarily by a piece of wire connecting your neutral and ground busses. It could be via a bonding screw that you install in the neutral buss. This bonding screw has a specific location where it is installed so that the neutral buss BONDS to ground. If you do not have a bonding screw then a physical piece of wire would go between the neutral buss and the ground buss in the main panel only!

In subpanels, ususally, you run a ground wire with the feeders (wire carrying power from the main panel to the subpanel). In the subpanel you do NOT tie neutrals and grounds as they are already tied at your main panel.

With isolated grounds (at least with what we have to do in commercial applications) we would run all the isolated grounds to their own ground buss in the subpanel. Then, a ground wire would run from the subpanel all the way back to the main panel and attach to the main ground buss in the main house panel. Grounds not required to be isolated would terminate at the subpanel.

I doubt this cleared anything up but it may help him answer some questions.

As for dimmers, I tried and wanted, the regular ol' DIY store dimmers to work. All I got was hummmmmmm. I bought some variacs off EBay and installed those. The hum dropped noticeably in the live room. I *still* have to install variacs in the control rrom though so not all of my problems are gone

If you look on EBay, and know what you are looking for, you can get the variacs cheap. I got three for $40 a couple months ago. The only thing is having the know how to install them. They aren't hard but if you aren't experienced in dealing with electricity you might consider hiring your electrician to put them in.

-Brad

Ross H · Post by **Ross H** » Sun Feb 18, 2007 10:40 am

Brad,

Thanks for your input...which variac dimmers did you purchase?

Ross

lunatic · Post by **lunatic** » Sun Feb 18, 2007 10:53 am

Variacs, or auto transformers for the generic name, are sized in the amount of amps they can deliver. So, you'll need to add up the wattage of lights you are driving, and divide that by 120 (for 120 volts assuming USA power). This will tell you what amperage of variac you need to get. For example, if I need to power and dim three, 65 watt, lightbulbs I would do this (65 * 3) / 120 = 1.625. So, to make it easy, you round up to 2 amps. I think the smallest variac I bought is a 1.75 amp variac. It was suprisingly small.

I bought the Staco brand of variac. The first one I bought was direct from Mouser and it cost about $120. However, I needed to power eight, 65 watt bulbs, so I needed a 5 amp variac. If you buy them off of EBay you want to make DARN sure they are in GREAT condition.

While you are at it, go read Ethan Winer's article on studio hum and buzz. It's a great read with a TON of information in it, http://www.ethanwiner.com/dimmers.html It's where I got started.

You can see photos of one of my installs here, http://www.johnlsayers.com/phpBB2/viewtopic.php?t=6891

There's a photo of the 5 amp and the 1.75 amp variacs.

-Brad

Ross H · Post by **Ross H** » Sun Feb 18, 2007 11:51 am

Smokin!!! Thanks Brad.

Considering the studio lights are on the same power as all other lighting in the house, do you know if I will be required to replace ALL dimmers in the entire house, or at least on the same floor as the studio, or is it just the dimmers that are within the general area of instruments and tracking???

RH

lunatic · Post by **lunatic** » Mon Feb 19, 2007 2:01 am

That's a good question and I'm not completely sure I know the answer. Do you have very many dimmers to change out? How many dimmers and switches are there just for the studio?

Changing out switches and dimmers is pretty easy. As a troubleshooting step, if there aren't many dimmers in the studio, you might start with changing the dimmers in the studio to just the basic cheapo toggle switches from a Home Depot or Lowe's. Then see if the problem disappears. If it does then you know the problem is isolated to that room. If it doesn't then you might have to change 'em in the whole house.

I wish I knew, for sure, the answer to that question. Keep us informed as I would love to know how this turns out. Dimmers, variacs, grounding, etc, have started to really become interesting to me. I'm trying my best to learn as much about them as I can.

-Brad

stuntbutt · Post by **stuntbutt** » Thu Feb 22, 2007 2:31 pm

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.

Ross H · Post by **Ross H** » Fri Feb 23, 2007 9:45 am

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

Ross

Eriksmusicproduction · Fri Feb 23, 2007 5:26 pm

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

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

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

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.

Ross H · Post by **Ross H** » Sat Feb 24, 2007 6:47 am

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

lunatic · Post by **lunatic** » Sat Apr 07, 2007 4:34 am

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