1
Occupational Safety and Health Administration (OSHA) 1910.269 states:
“Equipotential Zone. Temporary protective grounds SHALL be placed at such locations and arranged in such a manner as to
prevent each employee from being exposed to hazardous differences in electrical potential.”
Like a “Cluster Ground Bar” used on a wood pole, the Equi-Mat™Protective Grounding Grid is designed to work in parallel
with properly installed temporary grounds. While standing on the grid, an area of “equipotential” is provided for personnel
during installation, operation and maintenance of electrical equipment, and working near utility vehicles.
The purpose of this document is to provide the necessary instructions to install and use the Equi-Mat™Protective Grounding
Grid. This document does not intend to inform the users of all the potential hazards related to electricity.
If a ground fault occurs on a grounded “Y” or “star” system, a Ground Potential Rise (GPR) will exist around the fault area
and at the substation that feeds the line. The capacity of the power system and ground resistance determines the voltage rise.
The ground point is attempting to bring the phase voltage to zero. The capacity (resistance and capacity to handle current) of
the ground system determines how close the phase voltage is to zero. The resultant is the GPR.
There will never be a true equipotential zone. There will always be some current flow through the worker’s body. The amount
of current through the worker depends on the voltage drop across his body. The desired situation is very high resistance in
the worker current path and very low resistance through the rest of the ground system. The lower the resistance of the “trip”
ground components, the less current that will flow through the worker. Therefore, it is imperative that the entire
grounding system be inspected to ensure low resistance in all cables, clamps, and connections.
Always inspect and clean all connections, grid braid, cables, clamps, and associated equipment before use.
Ensure all connections are clean and tight before moving into the work area.
Important Instructions
for
Hubbell Power Systems / Chance
Equi-Mat™Protective Grounding Grid
Catalog Numbers: C6002850 thru C6002852, C6002989 thru C6002991
and PSC6003345 thru PSC6003350 (ASTM 2715, TYPE I, STYLE I)
Keep these instructions and warnings with the product for future reference.
Users must ensure, for their own safety, that they are properly trained for the job at hand and understand the
electrical circuit of the installed grounds. Improper installation of this grid and or protective grounds could
result in severe electrical shock injury or death by electrocution.
▲
! WARNING
Properly rated insulated tools or rubber gloves must be used to make all connections to equipment or to the
power system. In order for the EquiMat to adequately perform the intended function, it must be a secondary,
parallel path to adequate sized, properly installed protective (trip) grounds. Failure to provide an adequate
trip ground parallel path, to ensure adequate, low resistance connections, and properly install this equip-
ment could result in severe electrical shock injury or death by electrocution.
▲
! WARNING
Use extreme caution when moving on or off the mat. To minimize “step potential” (voltage differential from
one foot to the other) a worker must hop, or use an insulated step to move on or off the grid. Use care when
hopping that a slip and fall does not occur. The worker must remain on the Equi-Mat™Proctive Grounding
Mat in the event of a fault occurrence. Stepping off the grid in this situation could result in electrical current
thru the body resulting in severe electrical shock injury or death by electrocution.
▲
! WARNING
Each Equi-Mat™Protective Grounding Grid is supplied with a “ball stud” terminal (T6002364). This ball stud allows connec-
tions with “C” type, duck-bill or ball stud clamps. See Chance catalog. Before use, the supplied ball stud must be installed in
one of the lug terminals on the grid leads. Follow the instructions included with the ball stud. A bolt, lock washer, and hex nut
are supplied with one of the terminals. This is for use in connecting multiple ground grids to cover large or irregular areas.
(See page 3.)
P6002840
Rev. E 7/10
Hubbell Power Systems, Inc./ Chance
210 N. Allen St. • Centralia, MO • 573-682-5521
www.hubbellpowersystems.com
