| Charlie Richmond - Richmond Sound Design - Skype: charlierichmond |
| http://www.RichmondSoundDesign.com "Performance for the Long Run" |
| -- Free! - SoundMan-Designer - Show & Sound Control Software -- |
| -- I'm Linked In: http://www.linkedin.com/in/charlierichmond -- |
| "Let distribution undo excess - And each man have enough" |
| - King Lear |

---------- Forwarded message ----------
Date: Sun, 16 Mar 2008 20:21:49 -0800 (PST)
From: cpz@...
Reply-To: EntertainmentElectricity@yahoogroups.com
To: EntertainmentElectricity@yahoogroups.com
Subject: Re: [EntertainmentElectricity] Isolated Ground

In a flurry of recycled electrons, Pip Schulte wrote:

> One of the things they are trying
> to figure out is whether or not to put in any isolated ground plugs
> around the building.

Don't do it....

> From what I understand, in the sound amp room and
> the main control room they will have some isolated ground.

Isolated from what? (and for how long?)

> But he also
> has need to be able to plug a sound mixer in different parts of the
> building and patch into the system. So should he install some isolated
> ground plugs around the building or will plugging into any outlet be
> fine without getting that ground hum?

In general, and IMNSHO, isolated ground outlets are worthless. They're
hard to install properly, tend to be installed for the wrong reasons,
are hard to troubleshoot when something goes wrong, and... the moment that
the case of the mixer (or anything related, really) touches some other
metal, it becomes grounded through that, too. Which creates another ground
loop.

If he's concerned about ground loops, use proper audio wiring techniques
and isolation transformers as needed and leave the power/protectice ground
alone. (Some web searches for ground loop prevention will provice
some valuable info. Or search the forum at mikeholt.com for "isolated
ground".)

(In the steel mill where I worked, about once a year when -everything-
was out of service, the electricians would disconnect each iso ground
wire from the main bus and test it. About one in four showed continuity
back to the bus, and this is in a facility where you have trained
personal doing the work.)

Not that I have a strong opinion about it :-).

z!

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