Join presenter Marco Rossi from Amprobe to learn more about overhead and underground electric safety. This webinar will offer a comprehensive look at the current safety guidelines, discuss best practices, and teach you the basics of underground tracing techniques and equipment functionality.
2. What you will learn in this webinar…
• Safety industry estimates
• Overhead Electric Safety
– Risks
– Current electrical safety guidelines
– Safety best practices
– Why invest in high voltage NCVs?
• Underground Electric Safety
– Why is it important?
– Why invest in Underground Locators?
– How do Underground Locators work?
3. Introduction
Industry Estimates
• In the last 24 months, 173 accidents have occurred involving electrical
systems or equipment in the public and private sector
– 132 accidents involving contact with energized power lines/conductors
(overhead, underground and ground level)
– 31 accidents involving contact with energized transformers (or its
components)
– 10 involving contact with high voltage switch gears
• Accidents were triggered by arc flashes and electrocution by contact
(Source, OSHA)
• 30,000 Arc flash incidents occur every year in the US, 7000 burn injuries,
400 fatalities
• Every 6 minutes an underground utility line is damaged because
someone digs without the proper information
(Source, Industrial Safety & Hygiene News)
4. What likely causes these incidents?
1. Racking a circuit breaker
– Inserting or removing a breaker on a
live bus.
– Inserting or removing voltage
transformer
2. Loose panel wiring
– A loose conductor that shorts across
another conductor or ground.
3. Removing panel covers
– Retaining screws and fasteners fall
into an unsecured panel against a
live bus.
4. Hand tool shorted across two phases
– Experienced electrician cuts into live
cable with cable shears, shear handle
touches another phase.
4
Above Ground/Overhead
(Indoors – Outdoors)
5. Using test probes incorrectly
– The user gets distracted or
hand slips while measuring
phase to phase or phase to
ground while using old style ¾
inch probe tips.
6. Misuse of measurement tools
– Measuring across phases with
an inline amp meter creating a
short circuit.
– Measuring continuity on a live
circuit with a tool that cannot
withstand full voltage.
– Accidental shorting of phases
with a test lead tip that is too
long for the safety category.
5. Introduction
The essential element for electrical safety is to ensure
that the equipment in in an electrical safe condition
before any work is commenced
• Companies must know what NFPA 70E & OSHA 29.1926 Subpart V
and 1910 covers
• Understand Arc Flash, Incident Energy, & Flash Protection Boundary
• Standards, Enforcement, & Safe Practices
• Arc Flash Hazard Analysis & Direct Contact Electrocution
– Overhead
– Underground
6. What are the current guidelines?
CFR 29.1926.964 (OSHA 29) Overhead
lines and live-line barehand work
• Employer shall provide the protective
measures when employees are working
close enough to energized conductors
• Minimum approach distances should be
kept when approaching energized areas
• These distances can be defined by the
end-user
• All equipment should be insulated
• … More also with OSHA 29.1910 (see Slide
#23)
CFR 29.1926.965 (OSHA 29) Underground
Electrical Installations Guidelines
• Provides additional requirements for work
on underground electrical installations
• Cables with abnormalities are stated as a
risk of fault or indication of an impeding
fault
• Employee shall de-energize the
conductor
• Cables retain energy, even de-energized
(particularly long cables)
• OSHA never clarified until 2003 what is
an underground utilities locating mean
High Voltage Non-Contact Detector Underground Cable Locator
with Fault Finding Capability
9. Surface Level & Overhead
Non-Contact High Voltage Detectors
Safety Distances based on sensitivity
10. Surface Level & Overhead
Non-Contact High Voltage Detectors
DOs & DONTs
• Preferred due to strong electric fields
– Direct contact is not required
– Only one probing stick needed
– Can test taped connections
• Shield conductors cannot be tested except at terminal Connections
– Spiking tool may be necessary to verify shielded conductors are de-energized
• Will work only AC
• Will not indicate voltage on
– Grounded Enclosures
– Shielded Cables
• Might not indicate voltage if
– Cable is partially buried
– Insulated test point is against grounded metal
– Operator isolated from ground
11. Surface Level & Overhead
• MSHA Certification and Criteria
(Tests)
– Spark Ignition
– Current Limiting Resistor Test
– Temperature Test
– Small Components Thermal
Ignition Test
– Dielectric Test
– Mechanical Test
– Flash Current Test
– Drop Test
– Coal Dust Thermal Ignition
Non-Contact High Voltage Detectors
What matters
12. Surface Level & Overhead
• High Voltage Non Contact Detector
• Intuitive Visual and Audible Alert
• Low Range Setting
30 V ac – 1,500 V ac
• High Range Setting
1,500 V ac – 122,000 V ac
• Self Test
Not Necessary To Connect To Current
Carrying Conductor
• Drop Test
6 ft or 1.83 meters
• MSHA Certified
Non-Contact High Voltage Detectors
Amprobe TIC 300 PRO
14. Why Underground Utilities Locating / Tracing?
The consequences of striking underground
infrastructure can be significant
15. What likely causes these incidents?
1. Incorrect estimation of depth
– Excavate with wrong depth
– Come in contact with kV energized
lines
2. Overlapping of electrical wires
– Intersection of two underground wires
with different directions a different
depts
– User confusing which wire is
energized
3. Old circuit designs
– Underground circuit designed not
updated in a long time
– Contractors’ works impact directions
and depths not reflected on plans
4. Ground faults / Cable faults
– Wire damages (faults) impacting the
cable’s resistance
– This can lead to a voltage breakdown
15
Underground
(Outdoors)
16. • Cables have outer insulating jackets as a means of preventing water or
moisture from getting into the cable.
• While internal conductors of the cable have their own insulation,
ground water is frequently slightly acidic and can damage the cable’s
insulation
• Corrosion and degradation of the cable’s insulation are other issues
Ground & Cable Faults
Why Underground Utilities Locating / Tracing?
17. Technologies and Tracing Methods
Underground Utilities Locators
Advantages EM Induction Technology
– It can search an area from the surface to locate buried lines.
– It can measure depth from the surface.
– It can find cable faults and monitor
pipeline coating condition and locate
water leaks in plastic pipes.
– It can pinpoint the position of joints
in iron gas pipes.
– The equipment is portable.
– The equipment is easily handled and is
successfully used by workers.
– The technique works in all soil conditions
– The component parts of the technology are
low cost. Sufficiently low cost to be purchased
by small contractors or large fleet quantities
19. Underground Utilities Locator
Fluke Confidential
Transmitter
Receiver Signal Clamp
Test Leads Kit
& Ground Rod
Replacement
Fuses & USB Cable
Carrying Cases
AA Batteries
(Rx) & D-Cell
Batteries (Tx)
20. Underground Utilities Locators
Type of Signals
Technologies and Tracing Methods
Passive Signals
Generated by Environment
Active Signals
Generated by Locator’s Transmitter
- Direct Connection
- One cable to the target line, the other to
ground
- Clamp
- Induction of a signal into a cable, without
making a direct connection
- Induction
- Induction of a signal into a cable or pipe, by
placing the transmitter on the surface over
the target line
- Power Utilities
- Power transmission & distribution networks
(50/60Hz & related harmonics)
- Radiofrequency
- Radiofrequency transmissions (15 kHz –
28 kHz & related harmonics)
- Application Specific
- Signals from specific applications (CATV,
Cathodic Protections, etc.)
21. Passive Tracing Mode
– Two tracing modes supported
21
50/60Hz
Locates energized cables with 50/60 Hz voltage
No transmitter needed –EM field directly from circuit
Will not work with DC Voltage
Most popular troubleshooting method for location,
requires field knowledge
To avoid when having two or mode energized wires
overlapping – lack of accuracy
No depth estimation; no compass indicator (“Arrows”)
Radiofrequency
Locates metallic utilities (pipes, E/DE cables)
Detects reflected RF waves from utility
Reflected RF waves come from MF to UHF (radio, TV, cell
phone towers)
Receiver will detect multiple utilities conducting the signal
Perfect for outdoors; to avoid indoors
Works E/DE circuits, but not accuracy (best for location)
Passive Tracing Mode
22. Active Tracing Mode
Active Tracing Mode
– Supported with three modes
• Induction
• Signal Clamp
• Direct Test Leads Connection
– Requires Transmitter
– Receiver will detect unique
electromagnetic field of 8kHz or 33kHz
signal generated by the Transmitter
– Will work on Energized and De-
Energized electric circuits and metallic
utilities
– Provides depth estimation and
directional compass
– Non-Contact signal injection supported
(Induction and Signal Clamp modes)
and Contact signal injection (Direct
Tests Leads mode)
22
Induction
Signal Clamp
Test Leads
23. UAT-600 Series Tracing Modes & Techniques
Selecting Tracing Mode
Advantages Drawbacks
Passive 50/60Hz • No need to use transmitter
• Detects Energized Power Wires
• Effective for quick troubleshooting
• Does not work with de-energized circuits
• Does not work with non-electrical utilities
• Does not provide depth estimation and compass
orientation
• Inaccurate when more than one wire
Passive Radiofrequency • Ideal for metallic pipes detection
• RF always present
• No need to inject 8kHz / 33kHz signal
• Cannot be used indoors
• Noisy in an ambient close to structures (towers, buildings)
• Might not be accurate due to other utilities frequency
noise
Active Induction • No need to connect accessories
• Propagates unique 8kHz/33kHz signal to
filter
• Provides depth estimation and
directional compass
• Can work also with metal pipes
• Receiver should be at least 20 m. away from transmitter
when on beacon mode
• Transmitter should be at least 20 m away from structures
(radio towers, buildings)
• Transmitter should be aligned with direction of wire
Active Signal Clamp • No need to connect directly to the circuit
• Best for places where main terminal
(substation, juncture box, breakers
cabinet) hard to reach
• Might spread signal with other wires if not properly secure
around the cable
Active Direct
Connection
• CAT IV 600V certifies; can connect to
any hot line below 600V
•Accurate, clean signal
•Safe!!!
• Requires access to hot circuit conduit / terminal
• Might give false positives if not deployed with ground rod
25. Additional Questions or Comments?
Email Christina Spearman cpearman@transcat.com
Transcat: 800-828-1470
www.transcat.com
For related product information, go to:
https://www.transcat.com/brand/amprobe-store
