9.1 Bonding and Grounding

8/10/2019 9.1 Bonding and Grounding

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Chapter 9

Bonding and Grounding


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Objectives

Describe why the cable should be bondedDescribe bonding and grounding

proceduresDefine Bonding and Grounding Explain Safety Benefits and intent ofbonding and grounding a cable dropsystem.


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Ground Versus BondGround:

a conducting connection, whetherintentional or accidental, between anelectrical circuit or equipment and theearth, or to some conducting body thatserves in place of the earth.NEC Article 100Grounding is the establishment of an effectiveelectrical ground to earth.

Accomplished by connecting wires andhardware to an appropriate groundIn most cases, this ground is accomplished bydriving an 8 foot copper or copper/steel rod(grounding electrode) into the earth Usuallyplaced by power utility company


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Ground Versus Bond

Bonding: the permanent joining of metallic parts to form an electrically conductive path,that will ensure electrical continuity and thecapacity to conduct safely any current likelyto be imposed. NEC, Article 100In the drop system, installers will usually bondthe drop. Very rarely do they ground a drop.Bonding is the way all conductive cables andequipment are continuously connected.


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Ground Versus BondOnce the utility power ground rod is properly placed, allconnections to is are considered bonded to a common groundHowever it is not necessary to bond strictly to the ground rod itcan be done to any portion of an electrical system that is alreadyproperly bonded to an effective ground

In the situation below the medal conduits aregrounded because they connect to the medalcabinet which is connected to the powergrounding conductor which is bonded to theground rod


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Electrical Code Requirements

The NEC is recommended practices, but notactual law Communities must adopt and then it isenforceable by law


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Safety Benefits

Grounding provides a termination point forcurrents that might be present, or in the eventthat metallic surfaces are inadvertentlyenergized.

Metallic surfaces include:Faulty equipment-TVs, Set top terminals,

Direct contact with high voltage wires and equipmentInduced voltages from high voltage in close proximity,static and lightning

Any electrical device can become faulty and produce

electrical voltages


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Safety BenefitsBonding equalizes and limits thedifferences in potential betweenconductors.

Electrons take the path of least resistanceIf an individual simultaneously touches

two separate wiring systems (power, cableor telephone) that have different groundpotentials---Unwanted current will flowthough that individual to the secondsystem

The individual becomes the conductingpath---potential deadly.For this reason separate wiring systems ina house are bonded to a common ground.

Broadband,power andtelephonebonded tosame ground


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Difference of Potential


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Safety Benefits

Primary reason for bonding and grounding is toprotect human life

Technician as well as home owner

Secondary reason is protection of equipmentElectronic Equipment can be damagedShorted electrical circuits and electrical fires canresult from improper bonding and grounding


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Bonding Location

Choose where to bond the security box for thebonding block or bonded splitter:Considerations:

Proximity of the premises power ground or utilitycabinets

Available authorized bonding hardwareCable TV outlet locationsCustomer preferences


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Locating Security Box As close to power as possible


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Examining Bonding OptionsBonding thebroadband drop to theUtility PowerGrounding Conductor

To grounding rod


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Bonding to Utility Ground Rod

Bonding to utilitygrounding electrode(rod)

Examples of clamps forbonding to ground rod


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Bonding to Electrical MeterCabinet

Meter PanBondingConnector


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Bonding to Electrical MeterCabinet

Bonding toelectric cabinet

with meter boxbar clamp


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Unacceptable Bonding practices

Natural Gas piping systems Telephone grounding rod, clamp, wire orequipmentOutdated cable TV ground rodSharing the power companys grounding clamp

Outdated cable TV ground rod, usually inch indiameter and 3 feet in length.


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Whats wrong with thispicture?


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GoodGround ?


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Green Tax says:DO NOTREMOVEGROUNDING

WIRE CALL

CABLE TV


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Grounds

Grounds can be;Intentional

Of low impedance that has enough current carrying capacityto prevent buildup of voltage.

AccidentalUsually referred to as short or short circuit. A path withlittle or no resistance to ground created between circuit and

ground.ESD, example

Intentional Grounds protect equipment, Accidentalgrounds destroy equipment


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Bonding; Equipment Failure

CATV and electrical wiring systems arefrequently hit by

high amplitude, short duration currents from power

surges, lightning, and downed power poles These voltage potentials can destroy equipment.If all equipment shares a common ground it can

help bleed off these voltages. The VCR cable input can be smoked by voltagespikes when grounding is inadequate.


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Inside Security Box

7/16 th wrench usedto connect inputand output cablesto splitter


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Bonding Wire

Select bonding wire with current carrying

capacity approximately equal to that ofdrop cable needed (per NEC Handbook)

NEC Handbook articles 820 & 830 require bonding wire to be:1. Insulated,

2. Solid copper,3. Not smaller than No. 14 gauge with current carrying capacity approximately equal to that ofthe outer conductor of the coaxial drop cable

No. 14 wire is the minimum size required for Series 56 and Series 6 drop cablesFor larger coax No. 12 or 10 AWG (American Wire Gauge) will be required to comply with NEC


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Coaxial Cable Current CarryingCapacities

The size of the drop wire and itscurrent carrying capacity are directlyrelated.

The current carrying capacity of thedrop cable must directly correlate to thebonding wire capacity.

Note that Series 11 quad-shield cablecan carry current from 35-42 amps. Toproperly bond this cable, No 10 wire isrequired


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Bonding Block

A bonding block or grounding block ispictured here

One side connects to the Tap cable The other side connects to customer drop The hole is for insertion of the bonding wire

This device is usually attached to the outside of thehouseF-81 connector with attachment for ground.


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Bonding Wire

Attach the bonding wire to the drop cable bythe use of a bonding block or splitter.Insulated with rubber or other insulation andmade of copper or other corrosion-resistantconductive material.Identify it with a tag: This bond is not to beremoved.


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Bonding Wire (cont)

Keep it as short and straight as practicalBe sure it is at least #14 wire (#12 wire whenbonding to the frame of a mobile home) and hasa current-carrying capacity equal to or greaterthat that of the outer conductor of the coaxialcable.

Wire gauge table

http://www.reade.com/Conversion/wire_gauge.html
http://www.reade.com/Conversion/wire_gauge.htmlhttp://www.reade.com/Conversion/wire_gauge.html


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Bonding OptionsCheck with your supervisor (or company policy) forthe bonding specifications of the system youmaintain.Bonding Options:

Customers electrical service grounding electrode or

grounding conductor.Metallic conduit on the load side of the power meter.Metallic conduit between and weather head and meterpan.

Electrically conductive cold water pipe.5/8 inch, 8 foot ground rod made of copper-clad orgalvanized steel.

http://www.lipower.org/residential/safety/powersupply.html

Details pg9.14
http://www.lipower.org/residential/safety/powersupply.htmlhttp://www.lipower.org/residential/safety/powersupply.html


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House Electrical

A - Service DropB - WeatherheadC - Service Mast / ConduitD - Electric Meter E - Main PanelF - 120 Volt Lighting CircuitG - 120 Volt Outlet CircuitH - 240 Volt Oven CircuitI - 120 Volt Outlet CircuitJ - Sub-PanelK - "GFCI" Protected OutletL - 240 Volt Water Heater

Circuit


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Only acceptable ifpaint and rust areremoved fromMetallic Conduit.Many powercompanies are nowusing plasticconduit which isunacceptable forbonding.


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Not all cablecompanieswill allow thistype of bond


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Should be zero volts and less than 25ohms of resistance

If a water faucet is to be used as aground, it should be verified with a VOM. There should be no voltageand a max of 25 ohms of resistance

Notice the spool of wire since thefaucet and power meter panel arelikely far apart. This will rule out

the use of PVC in the water system.


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Professional Preferences

Always choose to run a large quantity of coaxial cablearound the house instead of a large quantity of bonding

wire. When two or more buildings have a common servicebut each one has its own building electrode system,bond each building independently.

When only one power branch circuit is supplied and thepower service is grounded at the main building (forexample a house and a garage), a separate bond at eachbuilding is not needed


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Conclusion

Bonding and grounding is often the final step inthe exterior work of an install, but one you haveto plan for at the beginning of each install.

To do it well, you need to follow procedures,use accepted practices, and be sure your

workmanship is excellent.


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Links

Wire gauge tableGrounding Electrode

Documenting Cable Wiring ViolationsKramer.Firm's Cable Television SystemPhotos Home
http://www.reade.com/Conversion/wire_gauge.htmlhttp://www.bluevolt.com/CoBrandTemplate/images/CoBrand/BlueVolt/CourseDetail/CEU/2005NEC/demo/Demo/100-5.htmhttp://www.kramerfirm.com/pictureshttp://www.kramerfirm.com/pictureshttp://www.kramerfirm.com/pictureshttp://www.kramerfirm.com/pictureshttp://www.kramerfirm.com/pictureshttp://www.kramerfirm.com/pictureshttp://www.kramerfirm.com/pictureshttp://www.kramerfirm.com/pictureshttp://www.kramerfirm.com/pictureshttp://www.bluevolt.com/CoBrandTemplate/images/CoBrand/BlueVolt/CourseDetail/CEU/2005NEC/demo/Demo/100-5.htmhttp://www.reade.com/Conversion/wire_gauge.html

9.1 Bonding and Grounding

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