ERICO Practical Guide to Electrical Grounding - Manual (Page 108)

Conductor Sizing
Proper sizing of conductors is determined by many factors
such as industry standards, insurance requirements, local
codes, etc. These standards supersede any recommen-
dations in this book. The following is based on many years
of experience and NFPA 77 “Static Electricity,” 1994.
There is no single answer to conductor sizing, although the
following guidelines can be provided:
1. Conductors which are connected and disconnected
frequently should be light enough to provide an
adequate life. A 1/8 inch stainless steel, No. 6 AWG
extra flexible copper, 3/16 inch flexible bronze or
galvanized steel will carry the current required for
static grounding and will fit the majority of
applications.
2. Permanently mounted conductors are generally
recommended to be at least No. 6 AWG copper,
although conductors of #2 to 2/0 are generally used
because they are more sturdy. Copper busbar is
often used where mounted on a wall or floor. The
minimum size recommended is 1/8 inch by 1 inch
3. Outdoor grounding conductors are generally sized
for the particular facility and are larger than the
minimum required for static grounding
requirements alone. A minimum size of #2 AWG is
recommended. If fault currents must be considered,
a larger size may be necessary.
The question of insulation is important if the static
conductor or clamp comes in contact with an object that
may be electrically energized. Another consideration is the
operator being in parallel with the static discharge path.
If neither of these is a concern, then most users would
probably prefer bare conductors that are easier to inspect.
Metal doors must be bonded to the grounding system
in critical areas. (Fig. 6-15, 6-16, 6-17, and 6-18) A
personnel static ground bar is necessary to dissipate any
static charge before entering a room. (Fig. 6-19) Ground
bars are available for attachment of static ground clamps.
(Fig. 6-20)
Various bonding jumpers are available from plain or coiled
conductors to reels. (Fig. 6-21) Copper ground busbars
should be located at room periphery for easy access for
ground clamps. (Fig. 6-22)
Practical Guide to Electrical Grounding 100
Fig. 6-15
Coiling Overhead Door Grounding
Fig. 6-16
Door Operator
Ground To Door
Operator
#6 Bare Copper
Ground, CADWELD
Connection To Door
Track, Door Operator
And Sheet Metal Hood
To Steel Column.
CADWELD
Connection To
Overhead Door
Grounding Reel,
Mount To Door
Operator Sheet Metal Hood
Door Track
(Typ. For 2)
Coiling
Overhead
Door
Grounding Book 4/14/99 10/5/99 6:02 PM Page 100 (Black plate)