LOCATING BURIED UTILITIES

DIG SAFE B.C.Wednesday, March 31,2010

Cranbrook, B.C.

Fundamental Principles AndTechniques In Buried Utility Location

Presented By Brian Kidwell, Eecol Electric

WHY WE LOCATE BURIED UTILITIES BEFORE WE DIG

3 Workers Injured

What happens when you don’t locate……

LOCATING: THE 5 EASY STEPS TO SUCCESS

Understand Magnetic Fields – What are they?

Know How Magnetic Fields React.

Be Confident In Your Locating Abilities - Through Training And Experience.

Be Confident In Your Locating Equipment - Through Purchasing up to Date Technology.

Have A Basic Understanding Of What You Are Locating – The Infrastructure.

WHAT ARE WE ACTUALY LOCATING?

ALWAYS REMEMBER

Cable locators do not

find cables........

....they find magnetic fields.

WHY IS THIS SO IMPORTANT?

BECAUSE FIELDS DO THINGS THAT PIPES

AND CABLES DON'T DO !

THEY MOVE!!!

WHAT IS A MAGNETIC FIELD ?

A magnetic field is

radiated by a

current carrying

conductor.

WHY IS IT IMPORTANT TO KNOW ABOUT MAGNETIC FIELDS?

one arc. cycle

One Conductor Will Create A Field On Other Conductors.

The Result - - Target Field Moves Away From Alternating Fields.

THE TWO METHODS OF FIELD LOCATNG/DETECTION

First: PASSIVE POWER & RADIO

Current moves on source conductor causing magnetic fields.

Those Magnetic Fields Jump Onto Underground Pipes Or Cables As A Return Path.

Magnetic Fields Are Located.

THE TWO METHODS OF FIELD LOCATING/DETECTION

POWER MODE

RADIO MODE

THE TWO METHODS OF FIELD LOCATING/DETECTION

Second: ACTIVE CLIPS, CLAMP & INDUCTIVE

Most Reliable & Accurate Puts A Signal On Or In A Conductor.

Provides Better Information, Such As Depth Readings.

THE TWO METHODS OF FIELD LOCATING/DETECTION

The Best Method

Rated The 2nd Best

Rate 3rd Place

CLIPS: THE RULE OF THUMB

Ground Stake To Be As Close As 90deg As Possible. As Far As Possible (Max. Distance) Use Lowest Frequency

CLAMPS: THE RULE OF THUMB

Set-Up Similar To Clips, 90deg & Max. Distance Clamp Must Be Closed – Around Conductor Can Be Applied Anywhere Along Target Use 8kH Or Higher

INDUCTIVE SPILL: THE RULE OF THUMB

Will Cause More Ghosting / Multi-Signals Must Have Min. 60ft Between Rx & Tx Must Be Min. 90ft For Depth Readings Can Be 1 Man Or 2 Man Uses 65kH Or Greater

min. 10

paces

PEAK & NULL: TWO WAYS TO SEE THE SAME FIELD

PEAK: High Signal, High Tone

NULL: Low Signal,Low Tone, Arrows

Peak = Very AccurateLocation

Null = Can Be Off-Mark From 6”To 6-10ft

Peak

Null

13

DISTORTION: THE LOCATE KILLER

Multi-Conductors= Multi Fields(Ghosting)

Each Field Will Push & Pull OnOthers

Fields Are No Longer Round – Distorted Distorted Fields Are Harder To Locate Accurately

THE DISTORTION SOLUTION!

Low To Very Low Frequencies 512Hz Or Less (256Hz)

Always Locate In Peak Mode Test For Distortion With Null Mode Use A Transmitter With Medium To High Power

3 watts To 10 watts

THE DEPTH CONFUSION!

Correct Depth = No Distortion When Peak & Null Line-Up = Good Depth Also Use Lift Test - Lift 12” & Take 2nd Reading ALWAYS Compare Peak & Null

Peak

Null

d

Peak

Null

d

THE FREQUENCY ISSUE! WHY MORE THAN ONE?

Each Frequency Performs Differently Very Low (Under 1kHz) = Further Travel & Much Less Ghosting Medium (1kHz to 40kHz) = Medium Travel & Some Ghosting High (40kHz to 80kHz +) = Small Travel & Great Amount Of Ghosting

THE MINIMUM REQUIREMENTS FOR LOCATING

The Locator: A Basic Knowledge Of The Locating Principles A Basic Knowledge Of buried Utilities A Good Comfort Level On The Use Of

Equipment

The Equipment: At Least 1 Frequency From Each Category Clip Cables At Least 10ft Long A Ground Stake Of At Least 12” A Transmitter With A Minimum Of 3watts

REMEMBER!!!

Locating Can Be Accomplished Accurately And With Little Difficultly If: You Obtain Proper Locate Training & Support Use Current Equipment With the features that you

need..... don't cut corners! Ensure that you receive Full Training On All

Features & Techniques For Your Equipment Work With Your Local Utility Owners & Organizations (Such As BC One Call, BCCGA)

What’s New?

• Marker Balls for locating end of utility services, distribution boxes.

Color Coded as per Utility Colors, e.g. Yellow- gas, Red- power

• Tracer wire or Marker Tape for ease of locating PVC water waste services

• Flexi Trace & Sonde accessories for additional locating capabilities of PVC/Plastic services

• G.P.S, Data Logging, BlueTooth wireless line of site

What’s New?

• CERTIFICATION-

• BC RoadBuilders- Utility Gradesperson program

• WorkSafe BC/BC Safety Authority Initiative - Locator Certification

DIG SAFE, B.C,,Cranbrook

Questions?

Thank you!