Bonding AV Rack

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Jose cisnero

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I have to bond a metal rack for AV equipments, the electrical inspector asked to use #10 and another inspector said #8 does anybody know What size conductor to use to bond an audio en video equipments metal rack.?
 
The NEC would consider the rack bonded (thanks for using bonded not grounded) by the EGC in the supply circuit. You could respectfully ask the inspector for a code reference... but often audio equipment bonding is done to other standards, and recommended practices.
What are you bonding to (from the rack)?
 
What would you even bond the rack to? Do you have a ground grid, a ground bar, or even an exposed conduit? Otherwise, it is the equipment ground in the circuit feeding the rack, so match that wire size if you need a wire. Do you have a PDU in the rack, or just a bunch of cords going to the wall or a power strip on the floor? I like to use some special bonding screw from Panduit for rack mounted items. They are green, have thread forming threads, and have notches under their head to bite into the paint of the rack items to you don't have to scrape them. They make them in all the common rack screw sizes (10-32, 12-24, 6mm, and they have a mating bonding cage nut for square hole racks). I usually put these on the PDU and nothing else. To me, that effectively bonds the rack rails (which usually bonds the rest of the rack) unless there are some other things that could possibly energize the rack besides the PDU power cord.

 
The only problem at an AV rack is that some equipments don’t even have a grounding conductor in their cords so if there is a fault to ground “there no grounding conductor” the equipment is will get energized and all
Metal parts, it might damage equipments ( no grounding conductor so the OCPD won’t clear the fault). Not only that somebody might get electrocuted.. we are talking about a metal framing it needs to be bonded..
 
Jose cisnero said:
The only problem at an AV rack is that some equipments don’t even have a grounding conductor in their cords so if there is a fault to ground “there no grounding conductor” the equipment is will get energized and all
Click to expand...

If the power cord has only two conductors and it's UL approved, I don't see a problem.

And remember that most "required A/V system grounding" is only a step (if that) above snake oil.
 
Most of the things in that video don't matter except to comply with TIA or UL compliance or it is just plain overkill or unnecessary... I wish Cisco didn't put ground lug holes on all their switches. They make no note of what to do with it in the instructions or why it is there, so I don't know if we have to use it or why I would want to use it. It might make sense for shielded cabling.

Computer disk drives produce static electricity, but it will be dissipated via the equipment ground in the power cord. Static wrist bands have a 1 meg resistor in them so you don't get shocked wearing the band. That high impedance is still low enough to discharge static.

The video focused on computer and network racks. AV racks should have less issues. Bonding the doors seems unnecessary in any case. I have bought racks with and without bonding jumpers on the door. I don't know what is going to energize the door unless you're running power cords through the door opening and pinch one. I usually remove the doors anyway.

Again, does the room you are putting this rack in even have a ground system to ground things to? Computer rooms typically do, and labs may. An AV room could, but many times a generic room is turned into an AV room.
 
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