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| Discontinuous Joints |
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| Require Bonding |
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| Bonding Jumper Not |
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| Required For Rigidly |
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| For Qualifying Facilities |
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| Bolted Joints |
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| Bond |
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| EGCs in the Cables or |
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| EGC Cables Are Not |
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| Required If Rating Of The |
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| Feeder Overcurrent Device |
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| Conduit | |||||
| Permits Using The Tray |
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| For the EGC |
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| Three Phase | ||||
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| Motor Installation | ||
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| Motor Control Center | ||||
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| Bond | |||||||||
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| EGC In |
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| Switchgear |
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| Cable |
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| Transformer |
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| EGC |
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| (Solidly |
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| Building Steel | ||||||
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| Grounded |
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| Secondary) |
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| Ground Bus |
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| Bonded To |
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| Enclosure |
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| Lightning | ||||
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| Protection | |||
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| Grounding | |||
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| System Ground |
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Correct Bonding Practices To Assure That The
Cable Tray System Is Properly Grounded
If an EGC cable is installed in or on a cable tray, it should be bonded to each or alternate cable tray sections via grounding clamps (this is not required by the NEC® but it is a desirable practice). In addition to providing an electrical connection between the cable tray sections and the EGC, the grounding clamp mechanically anchors the EGC to the cable tray so that under fault current conditions the magnetic forces do not throw the EGC out of the cable tray.
A bare copper equipment grounding conductor should not be placed in an aluminum cable tray due to the potential for electrolytic corrosion of the aluminum cable tray in a moist environment. For such installations, it is best to use an insulated conductor and to remove the insulation where bonding connections are made to the cable tray, raceways, equipment enclosures, etc. with tin or zinc plated connectors.
See Table 250.122 on page 51 for the minimum size EGC for grounding raceway and equipment.
Cable Tray Manual | Cooper |
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