Boom cages and boom guards afford limited protection from electrocution hazards.
They are designed to cover only the boom nose and a small portion of the boom. Performance of
boom cages and boom guards is limited by their physical size, insulating characteristics, and
operating environment (e.g. dust, dirt, moisture, etc.). The insulating characteristics of these
devices can be compromised if not kept clean, free of contamination and undamaged.
Proximity sensing and warning devices are available in different types. Some use
boom nose (localized) sensors and others use full boom length sensors. No warning may be given
for components, cables, loads, and other attachments located outside of the sensing area. Much
reliance is placed upon you, the operator, in selecting and properly setting the sensitivity of these
Never rely solely on a device to protect you and your fellow workers from danger.
Some variables you must know and understand are:
Proximity devices are supposed to detect the existence of electricity and not
Some proximity devices will detect only alternating current (AC) and not
direct current (DC).
Some proximity devices detect radio frequency (RF) energy and others do
Most proximity devices simply provide a signal (audible, visual, or both) for
the operator and this signal must not be ignored.
Sometimes the sensing portion of the proximity devices becomes confused
by complex or differing arrays of power lines and power sources.
DO NOT depend on grounding. Grounding of a crane affords little or no protection
from electrical hazards. The effectiveness of grounding is limited by the size of the (wire) conductor
used, the condition of the ground, the magnitude of the voltage and current present, and numerous
If the crane should come in contact with an energized power source, you must:
Stay in the crane cab. DON'T PANIC.
Immediately warn personnel in the vicinity to stay away.
Attempt to move the crane away from the contacted power source using the
crane's controls which are likely to remain functional.