Beyond electrical code requirements, why does the sub panel earth ground, with its own earth ground, need to be tied to the main electrical panel ground?
Thanks for the info. I'll test the phase of my PS units when I have them close enough for my test leads.
I have thought of pouring a concrete pier say 6' deep and 12" diameter mixing the concrete with an additive for conductivity. Do you know if graphite would work? I once knew but have since forgotten the correct additive.
There was an electrical testing facility here that dug out the entire parking lot about 12' deep and put in a conductive 4' thick conductive concrete pad full of rebar all tied together with what looked like bronze or copper clamps. It was at least 300' by 300' in size. I guess they wanted a low resistance ground.
I have learned to appreciate the need for the one point of neutral tie in at the service panel and the tie to ground for lightening. And why the grounds must be tied together for safety,
One theory that lurks is; if all electric power seeks to return to the source, what is that source for the harmonic distortion and noise created by say a neighbors refrigerator or a faulty relay. And what about the energy used in powering a motor. That energy is not returning to the source. And why does the power get so quiet when it is really wet (rain) outside? These are my questions with my thinking that ground may have some influence as the "sump" theory goes. My local friend advocates a ground field of a half-dozen copper clad rods, each with a separate ground wire tie back to the main panel to lower ground resistance. He is a satellite engineer for the railroad, and is personally working on some changes to basic sigma-delta class D technology, so I do have some respect for his opinions.
My outlets are PS Audio Blaun (sp?) that replace normal outlets with a double box, and have a machined aluminum face plate. They feed into twin PS Audio power regeneration units (one on the front-end and one for the power amps). The feed is not currently from the existing sub-panel and the sub-panel only feeds a set of outdoor receptacles powering the pond and water features that I can completely turn off during listening. So the plan is in formulation. And the sub-panel may need to be redone altogether. I would only use lager gauge copper wire to create a dedicated audio feed. And historically, I used a metal (wound style) shield for the wiring from the sub-panel to the outlets, I bought my home with the existing wiring in place.
One oddity, at least to me, is that the existing sub-panel has the power take-off from the main panel by using two 20A breakers in the main panel. Both the main and sub-panel are less than 20' from the audio outlets.I always thought you just came off the main bus for sub-panel power.
Jea - that youtube is exactly what I needed to know. This forum is amazingly helpful because a handful of people, like you, care enough to share.
I live in Denver with my wife, Lori. My system consists of a custom built pre-amp using two B29 tubes and two small front end Mullards. It is with transformer or OTL switchable circuitry, and switchable capacitance so I can tune to the source. CD's need less and Vinyl more.
The amps are custom made with two 6C33C tubes per monoblock, 4 Mullards for the ancillary functions and a fairly massive output transformer. Class A/B with a solid 60W per side and 5 separate transformers for the various required voltages.
These amps are plenty to power my Soundlab U-2s. I prefer the U-2s 6' x 3' size over its larger brethren. These have been modified is several ways not easy to explain.
All running Audioquest cables, mostly silver over copper. I know that is way more than you asked, but I somehow thought you might find it interesting. One day I do a post on the pictures/system page, as the room is covered with my own acoustic diffusion and absorption panels which were sized and located by ear and trial and error. If you ever want to build your own, I do have some useful tips that will save you from learning the hard way like I did. And they work better than any of the stuff I tried that was made commercially at about 1/10th the cost.
A mix of diffusion and absorption is always a good thing!
High frequency hardness is a funny thing. While a lot of people focus on 1st and 2nd reflections, this can also be treated by generally adding absorption in the room. In other words, some of the problems are due to direct reflections, but some are just doe to how slowly or quickly it takes signals to decay.
You can experiment cheaply with throw rugs/blankets and putting other soft, absorbent materials on the walls. If that takes you where you want to go, then you are going in the right direction. Also, don't neglect the ceiling!
You may also experiment with toeing speakers outwards so you are not in the direct line of fire of the tweeter.
As an audiophile, we have had success in the past with using a ground field (multiple ground rods). My associates include a satellite engineer who made the original suggestion. I believe I have a audiophile grade system. I am using Sounlab U-2 electrostatics driven by 6C33C power tubes.
Since you brought up room treatments, I work on this every weekend. One question you may know the answer to is regarding 2" square wood block diffusion panels. While using longer pieces of 4" and 5" I understand this will increase the octaves covered over 1", 2" & 3". But what discernible sound effect would this have? it sounds to me as is there is some additional blurring in the mid-range.My focus is to tame some high frequency hardness.
Wguts, none of this is necessary nor will it improve anything.
What matters is that it all be referenced to a single point, where the neutral is bonded to it. Putting in a single, or 20 ground rods won’t help this at all. Follow the NEC, and local codes which may now require 2 rods.
I’d focus on your room acoustics. :)
The point of the ground is to act as an earth safety, which it can only do well if bonded to the neutral at 1 location.
Now if you want to run isolated grounds from the panel, that's fine.
So, the plan was to put a half dozen copper clad ground rods outside in the earth and run 6 separate ground leads to the sub panel. This should allow for an easier electrical noise pathway by lowering potential. If I connect this ground field back to the service panel, then I will connect with the noise from other home electrical devices, such as dimmers, etc. What I'm reading above is that 1) A separate ground field may cause breakers to not activate correctly and 2) cause a differential neutral voltage. I'm not clear on why multiple ground fields only makes sense for a separate building.
The sub panel powers primarily the stereo, but my neighborhood electrical is really noisy until about 10 PM. I do use PS Audio power regenerators, one on the front end and one on the amps. But they can't handle all the noise.
So, does anyone have a different opinion on what appears to be good advice above? And I do appreciate you guys taking the time to try and teach me some power grounding fundamentals. But I am a slow learner.
Earth "grounds" at different physical locations can have several volts of difference in potential. Depends on lots of factors. Only way to ensure it is at 0 Volts relative to AC is to tie them together. :)
Also, important, while you may have multiple grounds tied together, and even loop them, you may ONLY tie the neutral and ground together at one place, the service entrance. The service panel does not necessarily equal main. :)
Is the sub panel in the same building as the main panel or is it in an unattached garage?
What do you mean "with its own earth ground"? You cannot -- in the same building -- run a separate grounding conductor from a sub panel to a location other than where the house service is grounded. If there is a grounding conductor from a sub panel to, say, a water pipe that is more than 5 feet where the water pipe enters the house, the house water piping could be energized in the event of a fault.
The sub panel must have a ground bar that is bonded to the sub panel and the circuit grounds get attached to the bar. That ground bar must be bonded to the main service panel ground at the point of entry by either a separate wire or metallic conduit to the sub panel from the main panel.
The sub panel must have an isolated neutral bus that prevents the sub panel circuit neutrals from being grounded upstream of the service panel, resulting in neutral currents raising the potential on the sub panel metallic parts and ground.
If the sub panel is in an unattached building and fed from a breaker in the main panel, then the sub panel needs its own earth ground (to a ground rod) and does not need a grounding conductor to the main panel.
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