Bonding and Grounding Code

7/28/2019 Bonding and Grounding Code

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CHAPTER 13 ____ BONDING AND GROUNDING

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All Bonding & Grounding must be in accordance with the National Electrical Code (NEC).

Bonding is defined in the NEC as the permanent joining of metallic parts required to beelectrically connected. In a traffic signal, the term is used to describe the electrical andmechanical connection of conduit, metal poles,cabinets and service equipment.

Grounding is defined in the Code as a conducting

connection, whether intentional or accidental,between an electrical circuit or equipment and theearth, or to some conductive body that serves inplace of earth. By directing current along a path toearth, bonding and grounding reduces, but does noteliminate, the danger of unwanted electrical currentreaching the surface of equipment, causing damageand electrical shocks to anyone working on thesystem.

Ground rod electrodesare installed at all service points, in the handhole adjacent to the mastarm pole bases, and within pedestal concrete foundations as specified in the contractdocuments.

BONDING & GROUNDING


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CHAPTER 13 BONDING AND GROUNDING

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Rigid steel conduit runs are tiedtogether by screwing each length ofconduit together so that the ends ofthe conduit butt or come together

for the full circumference to providean electrically bonded andgrounded connection throughoutthe entire length of the conduit run.

Care must be taken that field cuts are madesquare and reamed to insure conduit endsbutt properly together.

Rigid steel conduit runs arebonded together in handholes bya solid #6 bare copper wireattached to the lug on threadbushings which are installed onthe open ends of conduit at theend of the run. A #6 greenstranded insulated conductor is

also pulled through rigid steelconduit as indicated in theContract documents.


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In pole bases, rigid steel conduit and grounding conductors are

tied to the grounding lug provided in the metal base utilizing anactive clamping grounding lug with mounting tang.

On an equipment pad, the ground rod and grounding connection is located in the signal servicecabinet.

Bonding of all ground rod electrodes to the #6 AWG stranded insulated green ground wire mustbe accomplished by exothermic welding.

Service equipment is tied to a ground rod if theservice is not on the equipment pad.


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All new signal systems must have a #6 AWGgreen insulated stranded grounding wire

installed from the signal cabinet to each polebase. This grounding wire may be daisychained from signal pole base to signal polebase. Consult the field wiring diagram fordetails. Each signal pole must have its ownground rod located in the handhole adjacent tothe signal base. A #6 green insulated strandedgrounding wire must run from the ground rodto the pole base. The ground wire coming fromthe ground rod will be spliced to the groundingwire running to the signal cabinet and to the #6

grounding wire running to the ground lug onthe transformer base using exothermicwelding.

The Equipment Ground Busmust be grounded to the sourceof power ground rod with a #6green insulated strandedground wire.


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In some cases rock may beencountered that does not

allow for a full depthfoundation. In these casesmodifications to thefoundation may be made withapproval for the Engineer.

In the cases where rock is encountered proper grounding may beaccomplished with a grounding plate or the required 15 footground rod installed horizontally.

At Service Equipment, a #6equipment grounding wiremust be properly connectedfrom the Equipment GroundBus in the cabinet to theneutral bonding bar of theservice equipment and toeach incoming conduitgrounding bushing lug.


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A separate No. 6 greenconductor is run throughthe conduit system andused for equipment groundpurposes. The separateNo. 6 green conductor isused in both non-metallicconduit (N.M.C.) and rigidsteel conduit (R.S.C.)systems.

Oxide inhibitor agent must be applied to all No. 6 grounding connections after both assemblyand final connection.

When existing conduit is incorporated into a new system, the Contractor must furnish and installnew bonding and grounding jumpers and new threaded conduit bushings on open ends of inplace conduit as directed by the Engineer.

Additional details on this subject arein the contract documents and mustbe reviewed. See 2545.3.R and2565.3.D.4.b


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Direct Buried Lighting Cable

Direct buried lighting cable must be 4/C #4 and meet the specifications in the Contractdocuments.

The direct buried lighting cable must be grounded and bonded as follows:The copper shield must be terminated on the equipment ground bus in the cabinet.The green conductor must be terminated on the equipment ground bus in the cabinet.

In the light pole transformer base the copper shield and grounding conductor must be bonded

together by drilling the copper shielding and placing it underneath the grounding lug beforebolting the assembly the pole base. The grounding conductor should then be terminated in theactive clamping grounding lug.


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Oxide inhibitor agent must be applied to all grounding connections after both assembly and finalconnection.

Documents

Bonding and Grounding Code