Mike Dolt Enterprises
Mike Dolt Enterprises
User: dspano, Location: Jacksonville, Florida
Asked on: Saturday, April 30, 2011 at 5:48 pm EDT
Answered on: Tuesday, May 14, 2024 at 4:50 am EDT
Question: Hi, I'm new to this forum, long time reader and any help would beappreciated.I'm on a job where my company has the structured cabling contract.Another electrical contractor has the contract for the cable tray andsleeves in the cable tray system. They put 4 inch EMT with push-onbushings through walls about the cable tray. The specs for the jobstate "short sleeves do not have to be bonded". So therewas not a question about the push-on bushings. Now we have pulledcable on about 1/3 of the entire project (800,000+ sf job and 2million feet of cable). theelectrical contractor is now going backand drilling 1/4 inch holes and using stake-ons with 1/4-20's throughthe side walls of the conduit to bond to the cable tray. In theprocess they have drilled through some of the cables that wereinstalled already. In the comm. rooms they are using ground lugsdrilled through the side walls of the conduit. Is this a listed or anacceptable means of bonding EMT for communications or any othersystem for that matter?
Bonding EMT for Communications
According to the 2020 National Electrical Code (NEC): Section 250.118(1) requires all metal raceways, cables, and other conductive enclosures to be bonded to the grounding system. Section 250.97 states that short sections of metal raceways or sleeves passing through walls or ceilings do not have to be bonded if they are effectively grounded by the metal parts of the structure. Section 300.9 prohibits the use of conduit bodies or fittings that pierce the side walls of the conduit unless listed for the purpose.
Push-On Bushings
Push-on bushings are not listed as a means of bonding EMT to a cable tray. They are only intended to protect the insulation of cables passing through walls or ceilings.
Drilling Through Cables
Drilling through cables is a serious safety hazard and can compromise the integrity of the cables. It is not an acceptable means of bonding EMT.
Ground Lugs on Conduit Walls
Drilling ground lugs through the side walls of EMT is also not an acceptable means of bonding. Conduit bodies or fittings must be used for this purpose.
Acceptable Methods of Bonding EMT to Cable Tray
The following methods are acceptable for bonding EMT to cable tray: Bonding Bushings
Listed bonding bushings are installed on the ends of the EMT and connected to the cable tray.
Condulet-Type Fittings
Condulet-type fittings are listed for bonding EMT and are installed on the side walls of the conduit.
Grounding Clips
Grounding clips are listed for bonding EMT and are installed on the ends or side walls of the conduit.
Conclusion
The electrical contractor's method of drilling holes in the EMT and using stake-ons through the side walls is not a listed or acceptable means of bonding EMT for communications or any other system. It poses a safety hazard and can damage cables. Proper bonding methods must be used to ensure the safety and integrity of the electrical system. Flag for review