staying alivewhen the power lines come down: post-storm safety and electric utility familiarization
TRANSCRIPT
Warren RogersSafety Supervisor, Eastern ConnecticutConnecticut Light & [email protected]
Staying AliveWhen the Power Lines Come Down
Post-Storm Safety and Electric Utility Familiarization
Michelle LowtherPrincipal
Continuity [email protected]
Electrical System Awareness - Surviving the
Aftermath and the Beforemath
Warren Rogers - CL&P Safety
What Is Electricity?
Voltage
Current
Resistance
The flow of electrons from one atom to anotherin a complete circuit
Strength of the electrical pressure
Electric flow in a conductor
Resistance to the flow of current (in Ohms)
GREAT ELECTRICAL CONDUCTORS
Substation
Riser
Transmission
Distribution
Underground 23 Kv
Riser
Cutouts/Fuses
Primary
Insulators
Cross Arm
Recloser
Primary Voltage Conductors – 3 phase
Secondary Voltage Triplex
Shy bird
Bare copper primary
Primary
Secondary
Phone/cable
Transformers
Fuses
DANGEROSHA/NU’s Rule for
NON QUALIFIED PERSONS
MINIMUM - 10’ FOOTCLEARANCE FROM
ANY OVERHEAD LINES
Triplex Secondary Conductors
Primary
Secondary
Triplex120/120neutral
FREE SERVICE
Improperly installed generators have the potential to back feed downed wires
Step Potential - The potential gradient developed across the surface of the earth as a result of current flowing through the earth
Touch Potential - The potential measuredfrom an object that may be touched andthe earth one would be standing on
Broken Primary
Touch potential
Step Potential
Step Potential
Could the guard rail be energized ?
Phase of 23kv after three shots of Recloser
Phase landed here
Was there any step and/or touch potential?
Car vs Pole - Primary knocked off pole onto street, then car hit hydrant flooding street. 2 Good Samaritans died running to help car when they steppedinto water with down Primary. Seven others seriously injured attempting to rescue the 2 GS’s.
Effects of Electrical ShockCurrent (amperage) is the killing factor in electrical shock.
EFFECTS OF AC CURRENT ON AVERAGE HUMAN1 Milliampere (mA) Slight Tingling - Threshold of perception(1/1000 amp)5 mA Sensation of shock - can let go
Accepted as maximum harmless current (GFCI TRIPPED)
6-30 mA Painful Shock - Still have muscular control
50-150 mA Painful Shock - Loss of muscular control200 – 500 mA *1,000 – 4,300 mA* Ventricular Fibrillation - Heart leaves its * OSHA beating pattern and goes into a vibrating
mode before shutting off10,000 mA Cardiac Arrest, Severe Burns & probable Death * OSHA
15,000 mA Typical home circuit breaker (Breaker in panel tripped)
Ground Fault Circuit Interrupters - GFCI – Saves lives !
Why Men Invented GFCI’s
Fatality - exit wound after aluminum ladder contact w/secondary service
Stay Alive – Stay in Vehicle,Call 911Tell by-standers to stay back Stay in vehicle until utility company tells you the area is safe
Never trust any wire, primaryOr Secondary, to be safe until the utility rep says it is !!
Michelle LowtherPrincipal
Continuity [email protected]
(832) 594-8286
Housing for critical personnel when you need it most.