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My test engineer suggested sinking a ground rod through the floor right next to the test stand so that the chassis could be grounded. Our facilities mgr was not on board with that plan until we showed him that the building ground was floating at 500+ mA! The ground rod worked. To be effective the ground wire must be thick and short. The ground rod must be near the equipment. The ground was connected to the chassis only. @ tonywinga I have attended numerous Power Quality seminars over the years and this type of discussion always comes up. Usually the equipment comes from Europe. Specs for the equipment will say a ground rod shall be installed next to the equipment and connected to the metal frame of the equipment or connected to the provided ground lug. The electrician follows the specs *but* still connects the branch circuit wiring EGC (Equipment Grounding Conductor) to the metal frame of the equipment as required by NEC. I bet you see a problem... (Meets NEC. Aux ground rod is allowed as long as NEC 250.54 conditions are met. So the manufacturer’s Tech comes to see what is causing the problem(s) with the equipment. Where does he look first? "Well there’s the problem"... His equipment is connected to the building’s System Ground, (Grounding Electrode System) by the EGC. He tells the electrician his equipment has to isolated from the building grounding system and only connected to the earth driven ground rod beside the equipment. Not only dangerous, it violates NEC. In the event of a Hot ungrouned conductor to metal frame ground fault how does the ground fault current return to the source? Through the earth? Not hardly. The breaker at the electrical panel will never trip. What protection will a person have from receiving an electrical shock if he touches the frame of the energized equipment with one hand, and his other hand, or some other part of body, is in contact with a grounded object that is connected, grounded, to the building System Ground? None! No protection at all! Here is a short video about the use of an aux ground rod. When watching the video substitute the whole house generator with audio equipment. https://www.youtube.com/watch?v=gg4wBI7bWgI . |
Millercarbon’s first post might sound like a joke (and I assume that was the intention), but there’s an element of truth to it. Ground rods in dry, low quality soil (common conditions) are not ideal. You want a low impedance path to ground and that isn’t easy to achieve. I’ve wondered how you can get around this. Multiple grounding rods should help. Some jurisdictions require at least 2. So would keeping the soil around the ground rod wet. I have to imagine there is at least one audiophile on this forum that has set up a sprinkler system to automatically water the area near the ground rod to keep electrical conductivity with the earth high. I’ve also wondered if putting a ground rod in a river bank or stream would meet code because that would for sure solve the problem. Right. I find dry prose to be so, uh, dry. I say, variety is the spice of life! Besides, everyone already knows only five nines pure copper rod extruded with long grain crystals and cryogenically treated are the only acceptable grounding rods. Then just as the room is the most important element in a system the ground is the most critical element in the, er, ground. If you have the bad luck to have built on poor soil this can usually be alleviated by bulldozing down to bedrock and backfilling with a minimum 20 yards of topsoil containing a minimum 8% herkimer diamonds and mahgister sandwiches. Or you eat the mahgister sandwiches while digging, I never could get that part straight? First of course you did a perk test for soil drainage, and have automatic irrigation to precisely maintain soil saturation as monitored by electrodes placed no more than 1m apart around the ground rod. Be sure to allow 200 hours for your ground rod to burn in, warm up your ground rod before listening sessions, and whatever you do suspend the wire going to your ground rod above the ground so it doesn't touch the ground until it reaches the ground. Seriously. |
- 35 posts total