Page 7 - Crane and Rigging

Chapter 3 - Crane Safety

GROUND CONDITIONS

Placement of Mobile cranes on a jobsite can be hazardous if the ground is not inspected prior to
assembly. Ground conditions can determine a number of factors such as equipment setup, material
staging, outrigger placement, and the type of support material to be used. Ground conditions can also
affect the load and the load rating of the whole lift. Proper support selection and ground inspection must
be planned. The Assembly / Disassembly Director or a Competent Qualified Operator may perform the
inspection however there are times that a Registered Professional Engineer must be consulted.

Considerations for crane and outrigger placement

• Different substrates withstand different load bearing capacities. Gravel, concrete, asphalt, and
dirt all have different limitations to how much pressure it can handle.
• Support material helps to distribute the weight to the ground. there are many different types of
support materials from wood, metal, and Kevlar. The type size and shape of the support
material will determine how weight is distributed to the ground.
• The slew angle is the angle of rotation of the crane boom (upper) relative to the crane carrier
(lower) This movement transfers weight independently among the outriggers. depending on the
load staging and placement this can affect crane and outrigger placement.
• Weather can cause hazardous ground conditions. daily and even hourly monitoring and
inspection may need to take place.

POWERLINE SAFETY

Overhead and underground power lines can be hazardous to crane and overhead gantry operations. In
construction and utility, the most typical hazard is overhead power lines. A site inspection will reveal if
overhead power lines will be an issue for crane and material staging. If a power line is less than 20 feet
during assembly, disassembly, or equipment operation use one of these three options to eliminate the
hazard.

Option 1 - Deenergize the power line and ground. This must be performed by the utility owner /
operator, and verified prior to assembly or disassembly

Option 2 - Maintain a 20 foot clearance. Ensure that no part of the equipment , load or line gets closer
than 20 feet.

Option 3 - If the line voltage is known and verified, use the table below to maintain a minimum approach
distance.

MINIMUM CLEARANCE DISTANCES
Voltage Minimum clearance distance
(nominal, kV, alternating current) (feet)
Up to 50 10
over 50 to 200 15
over 200 to 350 20
over 350 to 500 25
over 500 to 750 35
over 750 to 1,000 45
over 1,000 (Established by the utility owner/operator or
registered professional engineer who is a
qualified person with respect to electrical
power transmission and distribution).
Overhead Crane and Rigging 7 Rev 3 November 2021