ERICO Practical Guide to Electrical Grounding - Manual (Page 69)

61 Chapter 3: Building Interior Bonding & Grounding
isolated ground (IG) receptacles. These IG receptacles are
frequently used for electronic/data processing equipment
applications. The use of a separate, “isolated” grounding conductor ensures that the cord-and-plug connected
equipment receives a “clean” source of power, free from
EMF or RF interference. Installers of IG receptacle should
note that the IG receptacles must be identified by an orange
triangle located on the face of the receptacle. The grounding
requirements for these receptacles are found in Section
250-74, Ex. No. 4. This section requires that the receptacle
grounding terminal be grounded by an insulated equipment
grounding conductor run with the circuit conductors. The
isolated equipment grounding conductor is permitted to run
through one or more panelboards provided it terminates
within the same building to an equipment grounding
conductor terminal for the applicable derived system or
service. Note that the isolated equipment grounding
conductor must be in addition to the regular equipment
grounding conductor for the branch circuit. Because the IG
terminal of the receptacle is isolated from the yoke of the
receptacle, a separate equipment grounding conductor for
the raceway system and outlet box still must be run.
LIGHTNING AND SURGE
PROTECTION
This is discussed in Chapter 2, Lightning Protection and
Chapter 7, Surge Protection Devices.
GROUND BARS AND GROUND BUS
Ground bus and ground bars have several applications:
1. Ground bus may be installed around the walls of a
room where accessible ground points are needed,
frequently for the control of static electricity (Fig.
3-30 and 3-32). The bus is generally mounted using
standoff brackets usually with insulators. (Fig. 3-27,
3-28 and 3-29) In installations with raised floors,
the bus may be mounted on the sub-floor (below the
raised floor) (Fig. 3-31). This is used only for
permanently attached equipment grounding
conductors.
2. Ground bus may be used as a single point to which
all equipment in a given area or of a specific type is
connected. This equipment is usually associated
with computers, telecommunications or radio/TV.
3. Special ground plates are available to meet your
specific needs. Figures 3-33 and 3-34 are two styles
specified on FAA installations which are protected
by plexiglass and include special markings.
Fig. 3-30
When mounting ground bus on the wall, either bus
or cable may be used to bond over the door way.
Fig. 3-29
Insulators and mounting brackets are available for
mounting your own bar.
Grounding Book 4/14/99 10/5/99 6:01 PM Page 61 (Black plate)