Star Grounding and the Home
This comes up a bit so I wanted to talk about it.
You may not, for safety reasons, create a separate grounding scheme for appliances fed from the same service. May. Not. Ever. That means that at the service entrance all the grounds and the neutrals must connect, preferably with zero Ohms between them and zero Ohms to the ground rod(s). I say preferably because, corrossion, splices, etc. These are rarely perfect.
However, you MAY run an insulated separate ground wire to the ground rods which feed the rest of the home. This is like a star grounding scheme in a piece of audio gear. You meet the code criteria, and you hopefully dissipate noise in the ground wiring of your home at the rod before it can reach your gear. You can achieve a very good version of this by running a sub panel to your audio room.
One interesting possibility that I’ve seen some power conditioners hint at is to use a coil with appropriate gauge wiring and low DCR to isolate the gear. This meets the code requirements that it can carry 100% of the current in the event of a short, and the coil blocks noise from the rest of the home. Pricey, cause it requires heavy coils, and because.... audiophiles.
It's the same thing, a wire to each ground rod or one wire to all ground rods is still a parallel connection to the service panel ground lug. The star connection moves from outside to inside. However you do it, just make sure there is less than 25 ohms to ground. Whether one way or the other is favorable to audio equipment is interesting to know and unfortunately we'll never find out until someone has some time to spare and experiment.
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Here’s what I know: there can be inter-component grounding differences (in design or implementation) that exist when a system is hooked up normally, assuming no issues with power in the room. I experimented (a fairly long time ago) with that Granite Audio device that allowed you to change the relative impedance among 3 different "channels" of external grounding cable-- essentially a star ground-- that did reduce (or seemed to) some of the noise of the system, but did not eliminate a hum from my amps, which are known to do that. (You lift or use one of those humbuster thingies). Yeah, I know, good design and all that, but yell at Vlad. This was before the commercialization of fancy ground boxes, like the Entreq and Tripoint, which I never experimented with. My power set up in this house, as of mid-2017, is very good as is the "dirty" power coming to me from Austin Energy. Though I spent for a big iso transformer that sits outside in a weatherproof NEMA cabinet (400 + lbs) and followed best practices in 10 gauge dedicated lines, I’m not sure how much difference star grounding would make. I did have the electrician wire a "clean ground" which ties back to the main system ground, and ultimately, to the house ground (per Code). But I'm not currently using that for anything and when I experimented with it--connections made to a heavy copper buss bar---it didn't seem to make much difference, so I undid all that extra wiring. Maybe that small reduction in noise is improved with the granules in the grounding box, and other esoterica, but I never made that leap. I think so much starts with the quality of power coming in, and the state of your main service panel and how you are wired in, that I would take the view of sorting that first, before addressing refinements. I know back in the day, ground lifting was common, but I have managed to refrain from doing that.
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1: Maybe i have misunderstod, but here in Denmark we can have 2 ground rods. One for the house installation and one for the hifi (if made correctly)
2: Noise ALWAYS travels the shortest way to the rod, then it can spread to the rod with lowest resistance and it also spreads to the rest of the system on its way to the rod if the grounding in your hifi system is not made correct. (noise is not so easy to get rid of) 3: If you connect your isolated ground wire to your house rod, then you can be sure that noice from house appliances get to your hifi system. 4: Make a seperate rod for your hifi and a isolated wire to the rod. Then take a ferrit core an clip on the wire the first place it is connected to another groundwire. The hifi rod can actually recive noice from other houses in the area if your rod have the lowest resistance in that area. You can overdo the ferric core (too much) becaurse: the bigger ferrit core, the bigger impact on the total resistance. Just try out how manny ferrit cores you want on the isolated ground rod wire and listen. When the music starts to sound borring, take some off again. You can do this on the hot wire too. In my experience it is not nessesary on the neutral wire. Unless you live in a industrial area, but even then.... Do this first and you have a solid "platform" for the ground rod in your hifi rig to "build further on" (sorry for my english) Regards |
In the mid west and Sierra's where there a lot of lightning strikes you can have 20 ground rods hooked to lightning rods they just all have to be bonded together, same for your stereo system. This is on the principal of marine grounding. We called it a star marine ground but it is pure marine tech.. Try fixing noise issues on a houseboat plugged into a dock AC supply..It's ALL marine ground (star). The boat is fiberglass, but you still have to share a common ground with an onboard generator, appliances and DC water pump motors. Everything has to run it's own ground wire and it cannot be broken or spliced unless it's in an explosion proof box. You can use a common block but it needs to be bonded also to the hull if it metal. In brackish water (the ocean is a hugh battery) You need something for the electrolysis to EAT other than the metal on the boat. Grounding bars!! AWAY from your onboard star points. ALL threads have to use Never-sieze. I worked on sea going rescue Tugs and fishing boats every now and then for Cat.. They can't break and they can't catch on fire.. What puke buckets.. Working in rolling seas in a foot of bilgewater and friggin' rats askin for something to eat. YUP I miss that job. I hate seals too, they are mean.. Look at the cute seal, sea going squirrels if you ask me.. Fisherman hate um.. |
In the US you can have as many ground rods as you want. The trick is that they must be electrically bonded together. The issue is life-safety and that the +- 120 VAC is referenced to it. If you have a different ground, it's no longer the zero point, and when a short occurs you are no longer guaranteed it will be at 0. |
@erik_squires Said:
In the event of a Hot 120V ground fault to an isolated dedicated ground rod the voltage WILL NEVER be zero. The Step Potential voltage around the ground rod could be as high as 120Vac. The return path for the 120Vac ground fault current travels through the ground rod, through the earth, back to source, the Utility Power Company’s power transformer’s grounded neutral conductor. There are multiple paths provided through the earth for the ground fault current to travel back to the power transformer’s grounded neutral. * Through the earth to the grounding electrode system of your home to the grounded neutral conductor in the electrical service equipment panel back to the source. * Through the earth to the Utility Power Company’s driven ground rod at the transformer for connecting the neutral to earth. * Through the earth to any of your neighbors grounding electrode systems to the grounded neutral conductor in the electrical service equipment panel back to the source. . |
No problem providing the AC mains branch circuit wiring EGC (Equipment Grounding Conductor) IS NOT LIFTED, BROKEN, or DISCONNECTED from the chassis of the audio equipment. The guy in the video calls the dedicated ground rod a supplementary ground. Added or serving as a supplement, additional...
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Agree...
And then it says: "The earth shall not be considered as an effective ground-fault current path." 2020 NEC 250.4(A)(5) . |
