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MULTI-PURPOSE SOUND SYSTEM <br />Section 16780 <br />15-1207 <br />G. Shielded cables of this section shall be grounded exclusively to Isolated Ground. <br />H. Cable shields shall be grounded to a single path. <br />Shield shall be tied to Isolated Ground at one end only, i.e., at the low potential <br />(receiving) end of run, unless otherwise noted. <br />G. Unless otherwise noted, at audio jackfields, tie shield at jack boot frame and float <br />opposite end. Bus each row of jack frames and run individual ground wire for each row <br />to rack IG bus bar. <br />H. Signal Ground provisions shall realize less than 0.15 ohms to the primary ground <br />connection. <br />Standard audio grounding shall be observed. All shielded cables require a continuous <br />shield from the source to the input. Shields shall be terminated at the input only, with <br />shields lifted at the source. This observation only applies to component termination <br />within a rack for balanced line level devices. This does not apply to microphone input <br />plates and microphone cables. Microphone lines and Aux lines shall be 22 Ga. <br />stranded with an overall foil shield with a drain wire. Intercom lines shall be 20 Ga. <br />stranded with an overall shields and a drain wire. Use underground (AQC series — <br />West Penn) wire where required. <br />3.7 SIGNAL POLARITY CONVENTION: <br />A. Maintain consistent absolute signal polarity at all connectors, patch points and <br />connection points accessible in the system. Where applicable, a positive polarity <br />electrical signal shall yield positive acoustic pressure from the loudspeakers. <br />B. Audio signal connector convention: IEC Standard No. 268, part 12 (1975); Circular <br />Connectors for Broadcast and Similar Use. <br />Signal Connector Wire <br />Signal high Pin 2 Red or White <br />Signal low Pin 3 Black <br />Signal Ground Pin 1 Shield, drain wire <br />3.8 PRELIMINARY CHECKS AND TESTING: <br />A. Check and test before completion of related or adjacent work of other trades, as <br />applies. Verify safe and proper operation of all components, devices, or equipment, <br />nominal signal levels within the systems and the absence of extraneous or degrading <br />signals. <br />B. Perform the following verification and/or testing procedures: <br />Proper yr ^viii iding of devices and equipment. <br />2. Integrity of signal and electrical system ground connections. <br />3. Proper provision of power to devices and equipment. <br />4. Integrity of all insulation, shield terminations and connections. <br />24 <br />