The instructions in this manual are not intended as a 
substitute for proper training or adequate experience 
in the safe operation of the equipment described. 
Only competent technicians who are familiar with this 
equipment should install, operate, and service it.
A competent technician has these qualifications:
• Is thoroughly familiar with these instructions.
•  Is trained in industry-accepted high and low-voltage safe 
operating practices and procedures.
•  Is trained and authorized to energize, de-energize, clear, 
and ground power distribution equipment.
•  Is trained in the care and use of protective equipment 
such as flash clothing, safety glasses, face shield, hard 
hat, rubber gloves, clampstick, hotstick, etc.
Following is important safety information. For safe 
installation and operation of this equipment, be sure to 
read and understand all cautions and warnings.
Safety instructions
Following are general caution and warning statements that 
apply to this equipment. Additional statements, related to 
specific tasks and procedures, are located throughout the 
manual.
Safety for life
SAFETY
FOR LIFE
!
SAFETY
FOR LIFE
Eaton meets or exceeds all applicable industry standards relating to product safety in its Cooper Power™ series products. 
We actively promote safe practices in the use and maintenance of our products through our service literature, instructional 
training programs, and the continuous efforts of all Eaton employees involved in product design, manufacture, marketing, 
and service.
We strongly urge that you always follow all locally approved safety procedures and safety instructions when working around 
high voltage lines and equipment, and support our “Safety For Life” mission.
Safety information
DANGER
Hazardous voltage. Contact with hazardous voltage 
will cause death or severe personal injury. Follow all 
locally approved safety procedures when working 
around high- and low-voltage lines and equipment. 
G103.3
This manual may contain four types of hazard statements:
DANGER 
Indicates a hazardous situation which, if not avoided, 
will result in death or serious injury.
WARNING 
Indicates a hazardous situation which, if not avoided, 
could result in death or serious injury.
CAUTION 
Indicates a hazardous situation which, if not avoided, 
could result in minor or moderate injury.
CAUTION 
Indicates a potentially hazardous situation which, if not 
avoided, may result in equipment damage only.
Hazard Statement Definitions
WARNING 
Before installing, operating, maintaining, or testing this 
equipment, carefully read and understand the contents 
of this manual. Improper operation, handling or 
maintenance can result in death, severe personal injury, 
and equipment damage. 
                                                          G101.0
WARNING 
This equipment is not intended to protect human 
life. Follow all locally approved procedures and safety 
practices when installing or operating this equipment. 
Failure to comply can result in death, severe personal 
injury and equipment damage. 
G102.1
WARNING 
Power distribution and transmission equipment must 
be properly selected for the intended application. It 
must be installed and serviced by competent personnel 
who have been trained and understand proper safety 
procedures. These instructions are written for such 
personnel and are not a substitute for adequate 
training and experience in safety procedures. Failure to 
properly select, install or maintain power distribution 
and transmission equipment can result in death, severe 
personal injury, and equipment damage. 
  G122.3
iv
COMPANION II BACK-UP CURRENT-LIMITING FUSE INSTALLATION INSTRUCTIONS  MN132009EN