If you have a wallbox (permanently installed snake) in your studio, by code the metalwork must be bonded to electrical ground.
Rick,Bill Whitlock (of Jensen Transformers renown) has a great presentation on system grounding.It's definitely worth a read, then a re-read. Keep it in the bathroom, too...you never know when you might get the urge to read about grounding. :-)
XLR pin 1 is a shield and is only connected to the chassis at the connector. It's true that the Main Audio Ground (or star point) is also connected to the chassis. But that's their only connection together.Jim Brown has all the articles on his website.http://www.audiosystemsgroup.com/publish.htm
Hi Rich,Sadly, many of those who manufacture equipment have yet to see the light. I have a lot of those Gotham cables left over from 40 years ago, and had to clip the Pin 1 to shell jumper. They are otherwise very good cable, but no better than Belden 8412 and some excellent Gepco cables.The AES Standards for audio wiring (written jointly by Neil Muncy, Bill Whitlock, Bruce Olson, and myself with support from other members of the AES Standards Committee Working Group on EMC) all call for the following:For balanced wiring:Pin 1 - ShieldPin 2 - Signal HighPin 3 - Signal returnONLY inside ACTIVE equipment (including microphones), Pin 1 shall ALWAYS be bonded straight to the shielding enclosure (usually the chassis). "Active equipment" means something that includes electronics.Outside equipment, there should NEVER be a connection between Pin 1 and the shell. In other words, cables should NEVER have a connection between Pin 1 and the shell. Such a connection is provided inside the equipment. For purposes of these Standards, snake boxes, patch panels, and multicables are treated as cables, even though their terminations may be in boxes. A mic splitting system would be "active" only if it included electronics -- for example, a digital snake system that multiplexes many mic circuits on a single circuit.Those Standards are AES48, AES54-1, AES54-2, and AES54-3. They are free to download for AES Members. If you're not a member, you should be. In addition to access to those Standards, you'll become a member of your local section, where you can learn from other professionals in your area.Regards, Jim Brown
That said, would connecting the green conductor to pin 1, which is intertwined to the other two conductors break my line balance? Or is it inert because it has the lowest potential out of the 3 conductors and will therefore help absorb any stray EMF those conductors create?
Rick,Bill Whitlock (of Jensen Transformers renown) has a great presentation on system grounding.It's definitely worth a read, then a re-read. ................................
Really? For microphone signal level wiring?Steve.
Steve, I'm a bit late getting back to you on this because I wanted to get my facts straight. I'm working on a project at the day job right now that involves several P.Engs, so I asked one of them about it. All troughs and wallboxes must be bonded to electrical ground regardless of what wires will be in them. It may be because an electrical inspector doesn't know what voltage is on any of those wires, he just wants metalwork grounded.
Thanks for replying. It would appear that compared with us here in England, the US has a lot more regulations and inspections than we do.Here, if someone wanted a permanently installed, metal boxed multicore. it would just be fixed to the wall, plugged in and used.Domestically, we have rules about ground bonding metal pipework and public buildings require all exposed metalwork to be grounded, but that's about it.
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