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| Rack & Power / Earth https://mail.karaokescenemagazine.net/forums/viewtopic.php?f=1&t=16131 |
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| Author: | Nlouch [ Wed Mar 11, 2009 5:54 am ] |
| Post subject: | Rack & Power / Earth |
I am gonna start building up my new rack soon. I just want to check, before I go ahead - what do you all do about earthing/grounding? Currently my gear is plugged into 3-pin UK sockets in the rack, so each is earthed. But someone said something about earthing the actual rack itself??? |
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| Author: | EElvis [ Wed Mar 11, 2009 6:11 am ] |
| Post subject: | Re: Rack & Power / Earth |
If you have a power Conditioner in the rack, it is grounded through the rails to the rest of the equipt. The only problem you could have is if you are running powered speakers. I have had ground loops from powered speakers on differing circuits than the rack. |
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| Author: | karyoker [ Wed Mar 11, 2009 6:44 am ] |
| Post subject: | Re: Rack & Power / Earth |
Earth ground is exactly what it implies. With electrical power service heads it is achieved by a copper rod driven into the ground and in the breaker box it is the absolute lowest or neutral voltage potential whether lightning (power surges) or RF or audio. Conduit is connected directly to earth ground. The metal case of all electronic gear is connected to earth ground via the 3rd or green wire for absolute protection. Water in a bath tub is at earth ground due the conductivity of water through the pipes going into the ground. In fact some earth grounds were clamps on the cold water pipes. Permanent installations have tall 19" racks that are all steel and all the racks are connected together with a heavy copper strap and all are connected to earth ground. In radar and broadcast installations this is important for protection and keeping RFI to a minimum. In our case the common ground are the rails that the chassis are mounted to. These rails must be connected directly to earth ground. Again it is the most neutral or lowest voltage potential. I made the comment about a slant rack with the mixer on top. I like to run a ground wire from one of the top rails to a rail in the bottom. This assures a common ground and does not rely upon the ground with the green wire in the power cord going to the mixer. |
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| Author: | karyoker [ Wed Mar 11, 2009 6:49 am ] |
| Post subject: | Re: Rack & Power / Earth |
Quote: The only problem you could have is if you are running powered speakers. I have had ground loops from powered speakers on differing circuits than the rack.
On powered speakers TRS or 3 conductor cable must be used with balanced audio. |
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| Author: | karyoker [ Wed Mar 11, 2009 7:08 am ] |
| Post subject: | Re: Rack & Power / Earth |
Venues in older buildings might not be wired according to newer codes. To test grounds or proper wiring this tester can be used to test outlets. photo |
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| Author: | EElvis [ Wed Mar 11, 2009 9:18 am ] |
| Post subject: | Re: Rack & Power / Earth |
karyoker @ Wed Mar 11, 2009 8:49 am wrote: Quote: The only problem you could have is if you are running powered speakers. I have had ground loops from powered speakers on differing circuits than the rack. On powered speakers TRS or 3 conductor cable must be used with balanced audio. |
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| Author: | Nlouch [ Thu Mar 12, 2009 4:11 am ] |
| Post subject: | Re: Rack & Power / Earth |
OK, points to note: 1) I am mobile, not in one location. Often in new locations too. 2) I do not have a power conditioner. Moreover, nver seen any KJ with one in the UK!? 3) I use powered speakers. So, I can run a cable from my slanted rail to my front-rails, but how do I actually ground these? Run a cable to my power sockets? Thanks for all the feeback 
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| Author: | mchin99 [ Thu Mar 12, 2009 6:01 am ] |
| Post subject: | Re: Rack & Power / Earth |
Nlouch @ Thu Mar 12, 2009 7:11 am wrote: So, I can run a cable from my slanted rail to my front-rails, but how do I actually ground these? Run a cable to my power sockets?
Before each gig; dig a hole minimum 8 feet deep outside venue. Insert copper pipe or rod. Connect copper cable from pipe to rack. Cover hole with dirt. Good to go.   
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| Author: | karyoker [ Thu Mar 12, 2009 6:10 am ] |
| Post subject: | Re: Rack & Power / Earth |
A power conditioner has circuits such as an SCR that crowbars voltage spikes to ground. They also have filters to ground for higher frequency RF signals. In broadcast transmitter rooms for 600 amp 3 phase service they can get rather expensive. I assume you have a power strip for your rack. It should have the 3 prong plug on it. `When you plug one unit into it with a 3 prong the rail is at earth ground and all other units metal case is at earth ground. In other words they have a common SHORT ground that is not dependent upon their separate power cord grounds. If a building is wired to code and all the wiring is in conduits which are connected in the breaker box to earth ground power speakers can be plugged into the nearest outlet without any problems. Remember that electrical connections can work loose or corrode over a period of time then intermittents can develop. I hate to be a stickler but I have fought every natural or man made interference problem with faulty grounding both ashore and at sea. It is simple but at times can baffle the most brilliant engineers. |
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| Author: | karyoker [ Thu Mar 12, 2009 6:18 am ] |
| Post subject: | Re: Rack & Power / Earth |
Quote: Before each gig; dig a hole minimum 8 feet deep outside venue.
Insert copper pipe or rod. Connect copper cable from pipe to rack. Cover hole with dirt. Good to go. Shocked Mr. Green Surprised 
In the old days a big pit was dug next to the transmitter tower which had copper wire connected to the tower base. Then the pit was filled with horse manure then covered. I am very serious this was a common practice. WE also used to bury a truck radiator next to a CB base tower with the filler cap at ground level. Then pour rock salt into it and soak the ground around the tower and provide a good alkaline ground. BTW a neon transformer connected to a electric fence can knock the biggest bull to his knees. For the rest of his life he will not come near a piece of wire laying in the pasture. Only did it once... |
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