Transcript Overhead Power Line Training

1926.1408
COMMON CAUSES OF CRANE
FATALITIES
Rigging
Failure
15%
Load Handling
14%
Operator Error 7%
Electrocution
44%
Overload 7%
Dismantling Boom 5%
Wire Rope Failure 3%
Struck by Crane 3%
Miscellaneous 3%
COMMON MYTHS
COMMON MYTHS
COMMON MYTHS
ALWAYS ASSUME POWER LINES TO BE LIVE!

This video displays the effects
of a crew assuming the
overhead lines were phone or
cable, and not electrical.

Always assume overhead
lines to be electrical and live
unless the utility company has
provided notice that they have
been de-energized, and they
are visibly grounded.
POWER LINE HAZARD ASSESSMENT
MUST BE COMPLETED FOR EACH JOB CRANE IS USED ON

STEP 1: DESIGNATE WORK ZONE
 For
every job which we use a crane, we must first
designate the work zone.
OPTION 1
OPTION 2
Designate the work zone as the
maximum working radius 360
degrees around the crane
Use elevated visual aids such as warning
lines to mark boundaries of the work zone.
Not required to fully barricade the entire work
zone (example would be a short row of lines
on each side of the crane signaling where
operator cannot swing past and a row at the
far reach displaying the area that can’t be
boomed past)
POWER LINE HAZARD ASSESSMENT

STEP 2:
 IN
“WORK ZONE” DETERMINE IF CRANE OR RIGGING
CAN GET WITHIN 20’ OF POWER LINES
NO
YES
No further action necessary
Choose option below and have planning meeting
w/all onsite to discuss
OPTION 1: Have utility company deenergize & ground
OPTION 2: Maintain 20’ clearance at all
times by placing elevated warning lines
20’ from power lines and having a
dedicated spotter monitor distance when
approaching
OPTION 3: (use if needed to get close
to lines than 20’) Ask utility company
for exact voltage, and maintain distance
requirements of Table A (next slide) by
using elevated lines & spotter listed in
option 2
Table A – Minimum Clearance Distances
Voltage (nominal, kV,
alternating current)
Minimum clearance
distance (feet)
up to 50
over 50 to 200
over 200 to 350
over 350 to 500
10
15
20
25
over 500 to 750
over 750 to 1000
over 1000
35
45
(as established by the power line
owner/operator or registered
professional engineer who is a
qualified person with respect to
electrical power transmission and
distribution)
POWER LINE HAZARD ASSESSMENT

The hazard assessment criteria on
the previous three slides
discusses procedures assuming
the power lines are not known
exactly and presumed to be 350kV
or less, which is our typical
working environment.

When power lines are presumed to
be very high voltages and over
350kV, the minimum distance
kept must be 50’, rather than the
20’ discussed for voltages of
350kV and lower.
WORKING AROUND POWER LINES

Whenever power lines are within
the pre-determined “work zone”
and tag lines are used, the tag
lines must be of non-conductive
material.

A “dedicated spotter” or motion
limiting device must be used to
ensure the crane does not get
within the minimum distance of
the power lines. This spotter
must be a qualified signal
person capable of signaling the
crane
DEALING WITH POWER LINE EMERGENCIES


In the unlikely event that contact with a power line occurs, the
response of those on or around power lines is critical.
In general, riggers and other workers working around the crane
are in the most danger, however operators leaving the cab or
operating from the ground can receive injury or death.
The operator sitting in the cab on the left is at the same electrical potential as the crane,
therefore is most likely not affected, however the operator on the right working from the ground,
riggers and those around the crane at in significant danger.
DEALING WITH POWER LINE CONTACT


•
•
After the crane contacts power lines, the current
flows through the crane and finally through the
ground in a ripple pattern. Areas of high and low
fields circle the crane like ripples in a pond after a
stone hits the surface.
If a worker steps from between ripples, from an
area of higher potential to one of lower, the
electricity can flow between their legs and cause
injury or death.
OPERATORS SHOULD NOT LEAVE THE CAB UNLESS
ABSOLUTELY NECESSARY (fire for example)
IF EXITING CAB, JUMP FROM CAB AND SHUFFLE FEET IN
VERY SMALL STEPS AS YOU WORK AWAY FROM THE CRANE
PROCEDURES TO FOLLOW IF CONTACT OCCURS

Crane operator should remain inside the cab

All other employees must keep away from the crane, ropes, and load since
the ground around the crane might be energized

Crane operator should attempt to remove the crane from contact by moving
it in the reverse direction which caused the contact

If crane cannot be moved from contact, operator should remain in the cab
until power is de-energized

If operator must leave because of immediate hazard, jump from equipment
and shuffle feet in very small steps

Others should secure the area and keep all except for emergency rescue
who are aware of the hazard away
QUESTIONS?