Joeb, I hope Audiogon allows this response, as I resell cut lengths of Belden 8300 series cable for dedicated lines....
I would try a SHIELDED power cable for your dedicated lines, connected to better duplexes, and then use SHIELDED PCs to your components. I assemble simple power cords with inner full shield "drains" AND a SWITCHABLE outer third-wire safety ground, thus allowing you much versatility in organizing ground paths while maintaining excellent RFI protection. RSVP so I can help further. Cheers. |
i originally did my dedicated lines in a previous abode with a seperate ground rod though my secondary box was bonded to the main box. It sounded significantly better. Then a kind soul on audio asylum described with word s and pictures the mechanism by which a lightning strike would preferentially kill my system. I proptly went to a single house ground without significant degredation of the sound. |
This is a bit off topic, but my new listening room is being built over the garage, very close to the power line and a utility co. transformer. On wall runs paralell to the power lines a mere 10' from the wall. I am worried about electrical interference being that close. Perhaps Ernie and Gs5556 could respond?
thanks |
Stephen (Rphsvc), I think you have all the advice you need above, but may I point you all to a recent post for some related details: impedance mismatched ? And the reference: Video & Audio: Power, Ground, EMI, Noise in Cables Glen, would you comment on Joeb's question of adding a ground when there wasn't one and its installation and code implications? Or point to a post of yours? (perhaps I didn't see it...) And as per: 04-14-03: Subaruguru
Yes, except that you ALWAYS want to isolate the RF-noisy digital components from the low-level analogue (CDP, phono pre, tuner, etc.). That is why I also use EMI/RF filters on all my outlets. IMO, Redwoodgarden, if you got 'em, use 'em! But I might add that using isolated ground outlets might help by bringing all the power grounds back to the original panel ground in a star configuration (read Glen's and other's excellent posts). At least as far as the power ground is isolated from the equipment grounds locally. The equipment grounds will be star grounded at the common 3rd prong equipment ground. This also works well when using conduit. Use conduit and 4 wires for best results. (I used it for a Manhattan studio in an industrial area). This is quite safe and legal as long as all grounds end up together (ref. Glen) and there is little or no ground current. There should *never* be ground current (over 10 milliamps) unless there is a problem which is why I use GFIs to alert me to the presence of a difference in the return current on the neutral vs. the ground. Home GFIs trip at 5mA. |
Subaruguru, thanks for your help. I have two Mark Levinson 334 dual mono blocks, and one Bryston 7BST single mono block for the sub. I'm afraid that all of these amps can draw mucho amps when taxed. I have one 20 amp circuit for the Bryston and three 15 amp circuits for the two Mark Levinsons and the CDP. Do I need all four circuits or is this overkill? |
Yes, except that you ALWAYS want to isolate the RF-noisy digital components from the low-level analogue (CDP, phono pre, tuner, etc.). So if you run only ONE dedicated line keep your CDP OFF it! Better to run two lines...one for digital and one for analog. Even better to run THREE if you have big monos, so they can have their own fatter one. RSVP for more info....Ern |
I spoke to an electrical engineer who said that both dedicated lines as well as dedicated grounds can cause ground loop noise even if everything is grounded to one common utility ground poll. He recommended having as many stereo units on one line as possible. Is there any logic to this? |
Re the shield on the belden 83800 series. If you're using the simpler 83802 12/2, then of course connect the twisted shield at both the breaker bus and your outlets' grounds.
If using 83803 12/3 then you can ignore the inner shield OR connect it at the breaker to act as a drain. RSVP for more info. Cheers. |
If you run 2 grounds it would be: a) illegal in most places, and b) a sure-fire recipe for ground loop hums.
A ground is by definition at one point and that point is at the service entry. You are really not gaining anything and giving up a lot safety-wise with two or more separate ground points.
If your service is buried then your ground is most likely a ground rod. But it could be the water pipe also. Just bring the grounds back to the main panel the way it's supposed to be. Isolating the grounds from the receptacle boxes (if using armored cable) is all you need to do to minimize common mode noise from EMI/RFI. |
This brings up a good question for me as well. After moving into our new house (new to us, but built in the 60's)
I realized all the outlets were old, 2 prong, ungrounded lines. So after adding a couple 3 prong outlets for my surge protectors, I ran my own separate ground from those lines only. As all my electronics are hooked into that line, is there a potential problem? Why?
Thanks
joeb |
Thanks guys! I will skip the extra ground. There has been mention of using sheilded belden cable for a dedicated line. I was wondering how the sheild is connected: on one end to ground? |
Hi Stephen,
Don't run the grounds the way you described. If you ad an extra ground rod do it at the main service. Make sure you bond the new ground rod to your existing ground rod. Two ground rods are a bit much IMO. Feel free to research some of my tech talk threads for helpful hints on dedicated circuits. Sean, others and myself have discussed this subject more than once. I think we covered every possible scenario. My suggestions stem from over 20 years as an Electrician. |
Find your breaker box. You'll find the pole ground there. If you want to drive a ground in your crawl space, make sure it is of the correct diameter and depth specified by your local code. It would work find.
My home uses below ground wiring but there is a rod by the house where the power comes up to the meter from the ground. Check around, you've got a meter somewhere.
Your neutrals are tied to pole ground back in the box on the neutral buss. All of your bare coppers from you home are there also.
I honestly don't think you will accomplish a lot by using a ground rod, however. Use a isolated ground recepticle, however, of hospital grade(preferably a Hubble) |
dedicated lines are terrific, dedicated grounds are not, if there is a problem on this line of any sort all the overload will be dumped to your equipment or you. the local power companies ground is the most reliable and the sound will not be an issue |
