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Lesson Objectives• Identify the basic components of the

utility power distribution system.

• Identify how powerlines can cause wildfires.

• List mitigation measures to prevent powerline related fire causes.

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Introduction

• Powerlines can pose a threat to ignition of wildfire in various fuel conditions.

• Fires of this cause are generally large and damaging.

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• Generally start during dry windy periods.

• High winds blow trees across power lines.

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• Some states have passed laws requiring fire safe precautions for powerlines.

• Fire protection agencies can work closely with utilities to minimize customer and public safety.

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Basic Electric Utility System

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Power Pole Levels

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Powerline Equipment Related Fire Causes

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Fire Causes• Resistance

• Fault• Arcing

• Overload

• Flashover3F-09-P101-EP

Types of Fires

• Hardware function or malfunction

• Vegetation in contact with conductor

• Downed trees

• Animals

• Flashover3F-10-P101-EP

Powerline Hardware With Ignition Potential

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http://osfm.fire.ca.gov/powerline.html

Power Line Fire Prevention Guide

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Fuses

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Solid Blade Disconnect

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Lightning

Arrester

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Hot Tap Clamps

Good design

Bad design

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Split Bolt Connectors

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Indicators Associated With Powerline Fires

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Line Conductors

•Overload

•Line tension

•Line sag or sway

•Change in elevation

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Conductor Failure

• Splice failure

• Heat arcing

• Contact with trees

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“ “Burner” Burner” Tree on lineTree on line

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Insulators

•Dirty Insulators• Salt spray, dust

•Humidity up•Dew

• Early morning or night

•Foggy conditions

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Birds and Small Animals

• Large birds• Snakes

• Flocks of birds

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Transformers

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Service Interruption

• Frequency

• Type of interruption

• Phase to phase

• Phase to ground

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Fire Fire PreventionPrevention Mitigation Mitigation MeasuresMeasures

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Clearance Requirements3F-33-P101-EP

Annual meeting with utilities

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Discussion Items with Utility Discussion Items with Utility CompanyCompany

• Focus on high hazard, high risk areas

• Maintenance schedule

• Attention to high stress poles

• Conductor (powerline) inspection

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Summary and Review Lesson Objectives

• Identify the basic components of the utility power distribution system.

• Identify how powerlines can cause wildfires.

• List mitigation measures to prevent powerline related fire causes.

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