locating buried utilities dig safe b.c. wednesday, march 31,2010 cranbrook, b.c. fundamental...
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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
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 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
Second: ACTIVE CLIPS, CLAMP & INDUCTIVE
Most Reliable & Accurate Puts A Signal On Or In A Conductor.
Provides Better Information, Such As Depth Readings.
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
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