| 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: Mon, 17 Mar 2008 00:40:48 -0400
From: Eddie Kramer <eskramer@...>
Reply-To: EntertainmentElectricity@yahoogroups.com
To: EntertainmentElectricity@yahoogroups.com
Subject: Re: [EntertainmentElectricity] Isolated Ground

On 3/17/08 Pip Schulte sent:

> One of the things they are trying to figure out is whether or not to put in
any isolated ground plugs around the building. From what I understand, in the
sound amp room and the main control room they will have some isolated ground.
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 isolatedground
plugs around the building or will plugging into any outlet be fine without
getting that ground hum? What do you guys have in your buildings?

The isolated ground needs to run all the way back to the "main ground" of the
building or the sparely derived system. This can cost much money and may be
"value engineered" out. See the NEC

***
>NEC 250.146
>NEC (D) Isolated Receptacles. Where installed for the reduction of
>NEC electrical noise (electromagnetic interference) on the
>NEC grounding circuit, a receptacle in which the grounding terminal
>NEC is purposely insulated from the receptacle mounting means shall
>NEC be permitted. The receptacle grounding terminal shall be
>NEC connected to an insulated equipment grounding conductor run
>NEC with the circuit conductors. This equipment grounding conductor
>NEC shall be permitted to pass through one or more panelboards
>NEC without a connection to the panelboard grounding terminal bar
>NEC as permitted in 408.40, Exception, so as to terminate within
>NEC the same building or structure directly at an equipment
>NEC grounding conductor terminal of the applicable derived system
>NEC or service. Where installed in accordance with the provisions
>NEC of this section, this equipment grounding conductor shall also
>NEC be permitted to pass through boxes, wireways, or other
>NEC enclosures without being connected to such enclosures.
>NEC
>NEC FPN: Use of an isolated equipment grounding conductor does not
>NEC relieve the requirement for grounding the raceway system and
>NEC outlet box.
***

Note; This is from the 2008 code, it is the same for the 2005 code with the
exception of the last sentence, (Where installed...such enclosures.) that was
added for 2008


Who's going to the USITT conference ?







--
--------------------
Eddie Kramer IATSE #1 Member NEC Panel 15
Copyright 2008

------------------------------------

Entertainment Electricity Rules:

1) Be nice! Flame war participants will be banned.
2) Stay on topic (electrical issues related to entertainment--no
politics/religion, no mac/PC).
3) Don't take troll bait.
4) Think quality of posts, not quantity.

The moderators reserve the right to delete/ban anyone who doesn't follow these
simple rules.Yahoo! Groups Links