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Grounding and Bonding

Earthing an installation is vital for the safety of people and property. Furthermore it plays an active role in EMI.

Definition

The earth network is made up of all the metallic components of a building that are interconnected. These include beams, conduits, cable trays, the metal frames or devices. All such elements must be interconnected to ensure the earth network is equipotential.

Bonding and Grounding

Per NEC 392, the national electrical code section for cable tray, all cable tray systems must be properly BONDED, per section 259.96. To meet this requirement, Cablofil recommends that UL classified splices are used to join sections and that the cable tray be bonded to building steel or the facility grounding system every 50'-60'. By bonding the tray every 50'-60', the tray will maintain a low potential to ground which reduces EMI and provides a continuous path for stray currents. Steel trapeze type hangers clamped securely to building steel usually provide a solid bond. Cablofil standard splices (SWK, EDRN, EZBN, EDT, EZT90, RADT90) are designed to have less than 1 milliohm of resistance between connections and provide bonding between sections. These splices have been tested by UL as part of the cable tray grounding system. Painted Cablofil wire mesh tray requires the outer mask of the conductive surface be removed at each end of the tray prior to installing the (SWK) splice. This (SWK) splice provides a UL Classified Bonding continuity between painted tray sections. All cable tray needs to be electrically continuous per NEC 250.96. Standard Cablofil splices provide continuity per 250.96. Cutting and removal of cable tray sections still allow continuity per 250.96 and only affects the rare use of cable tray as the EGC. Use of cable tray as an EGC is rare since UL requires all multiconductor cables to contain an integral EGC and single conductor cables are only used in a few industrial applications.

Data Cables
Diagram
Dedicated Accessories

First and foremost, the installer must establish the cross section for the protective conductor. CABLOFIL offers a wide range of dedicated accessories:

GNDCL

GNDCL: Simple and cost-effective earthing connector made of tin-plated aluminium. Used for protective conductors with a cross section of between 6 and 35 mm.

GNDSB

GNDSB: Use on GNDSB every 60' and/or at the end of each cable tray run. If cable tray is used as an Equipment Grounding Conductor, use one on each section of tray for a code compliant installation.

Resources
Bonding and Grounding

Bonding & Grounding Brochure: Download the Bonding & Grounding brochure

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