bonding conduit for 70v sound systems

[ctown]

Hello, I live in Las Vegas. Clark County code requires wiring in many commercial places to be installed in metalic raceways (Type I or II A Construction). If a 70v distributed sound system wiring for ceiling speakers is put in conduit, does the conduit have to be bonded? NEC states that circuits 50v or more need to be bonded. Most 70v amplifiers employ class 2 wiring which in most cities, doesn't need to be in conduit. But in Vegas, due to the location of the wiring, sometimes needs to be in metalic conduit. So in short, if I decide to run 70v systems and class 2 and 3 speaker wire circuits in metalic conduit, dos the conduit have to be bonded?

 

[dereckbc]

IMO yes because it is likely to come in contact with other wiring.

 

[ctown]

IMO yes because it is likely to come in contact with other wiring.

Can I bond the metal conduit to a steel beam structure member and have the amplifier grounded by branch circuit receptacle. Is this ok or will it cause a potential difference to ground or other hazards.

 

[hbiss]

Can I bond the metal conduit to a steel beam structure member and have the amplifier grounded by branch circuit receptacle. Is this ok or will it cause a potential difference to ground or other hazards.

Building steel is fine. As long as the grounded raceway is not physically connected to a rack or other enclosure where the amplifier is also mounted you won't create the possibility of ground loops.

I'm going to assume that the reason for running this wiring in conduit is NOT because it is Class 1. If so the conduit would need to connect with the rack and other procedures for bonding might apply.

-Hal

 

[cadpoint]

IMO yes because it is likely to come in contact with other wiring.

Why, mimimun code is for all services for be run free of contact by a minumum of 2 or three inches, OK I'm free quoting Building codes...

Edit in
If thats what the AHJ says well, OK ...

 

[ctown]

Checking to see if steal beam is grounded

Checking to see if steal beam is grounded

Can I bond the metal conduit to a steel beam structure member and have the amplifier grounded by branch circuit receptacle. Is this ok or will it cause a potential difference to ground or other hazards.

Building steel is fine. As long as the grounded raceway is not physically connected to a rack or other enclosure where the amplifier is also mounted you won't create the possibility of ground loops.

I'm going to assume that the reason for running this wiring in conduit is NOT because it is Class 1. If so the conduit would need to connect with the rack and other procedures for bonding might apply.

-Hal

Is there a better way to ground conduit in a dropped ceiling. I fiqured a steel beem because it would be accessible. Are there any other common practices that would be better for me to bond to.

 

[chris kennedy]

NEC states that circuits 50v or more need to be bonded.

IMO these conduits do not need to be bonded. Only a few ART's from Chapters 1-4 apply to your install.

725.3 Other Articles.
Circuits and equipment shall comply with the articles or sections listed in 725.3(A) through (G). Only those sections of Article 300 referenced in this article shall apply to Class 1, Class 2, and Class 3 circuits.
(A) Number and Size of Conductors in Raceway. Section 300.17.
(B) Spread of Fire or Products of Combustion. Installation of Class 1, Class 2, and Class 3 circuits shall comply with 300.21.
(C) Ducts, Plenums, and Other Air-Handling Spaces. Class 1, Class 2, and Class 3 circuits installed in ducts, plenums, or other space used for environmental air shall comply with 300.22.
Exception: Type CL2P or CL3P cables and plenum signaling raceways shall be permitted for Class 2 and Class 3 circuits installed in other spaces used for environmental air in accordance with 725.154(A).
(D) Hazardous (Classified) Locations. Articles 500 through 516 and Article 517, Part IV, where installed in hazardous (classified) locations.
(E) Cable Trays. Article 392, where installed in cable tray.
(F) Motor Control Circuits. Article 430, Part VI, where tapped from the load side of the motor branch-circuit protective device(s) as specified in 430.72(A).
(G) Instrumentation Tray Cable. See Article 727.

 

[hbiss]

250.104(B). It doesn't matter what the conduit or raceway is for so 725 doesn't apply. It is a metallic system the same as building steel or the water piping system and just as likely to be energized.

Is there a better way to ground conduit in a dropped ceiling. I fiqured a steel beem because it would be accessible. Are there any other common practices that would be better for me to bond to.

If it is attached to the building steel with straps or Kindorf nothing further needs to be done. You can use a pipe clamp and run a bonding conductor back to the ground bar in a sub panel or back to the service ground if you need to.

-Hal

 

[chris kennedy]

250.104(B). It doesn't matter what the conduit or raceway is for so 725 doesn't apply.

Good catch Hal. I thought Chapter 7 was beyond 1-4. I stand corrected again. No posting before coffee kicks in!

90.3 Code Arrangement.
This Code is divided into the introduction and nine chapters, as shown in Figure 90.3. Chapters 1, 2, 3, and 4 apply generally; Chapters 5, 6, and 7 apply to special occupancies, special equipment, or other special conditions. These latter chapters supplement or modify the general rules. Chapters 1 through 4 apply except as amended by Chapters 5, 6, and 7 for the particular conditions.