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UNDERGROUND SYSTEM CONNECTION
AND PROTECTION
Nowhere in the distribution of electric power
are the problems of connecting conductors
and protecting them and equipment against
the effects of fault currents as complex as in
underground systems. For more than 70
years, BURNDY
®
engineers have worked
closely with utilities to develop devices for
connecting and protecting conductors and
associated equipment in underground sys-
tems. These devices, with their inherent
dependability and economy, have con-
tributed to the rapid growth of underground
systems throughout the country. To assist
utility personnel in more effectively selecting
and applying these devices, the engineering
talent and experience of BURNDY
®
have
been pooled to prepare this technical sec-
tion, and the catalog information that follows.
The devices are designed for use in both
radial and network type underground sys-
tems. Radial systems (Fig. 1) distribute
power economically except in high load den-
sity areas where a high degree of service reli-
ability is required.
Network systems (Fig. 2) have become stan-
dard for AC power distribution where load
density is high and service continuity must
be assured under nearly all conditions. The
improved equipment and methods which are
described in this catalog have been designed
to meet these secondary network system
requirements and to reduce the cost of
installation and maintenance.
Early Problems in Underground
Connections
Despite the many advantages of under-
ground distribution, a major problem was
that of making connections in congested
manholes or junction boxes. The necessary
procedure—soldering conductors, taping
joints, and wiping lead covered cable—was
so complex, that it demanded considerable
skill and was time consuming and costly.
This involved procedure had to be repeated
each time a service was added to a main.
When completed, the multiple-branch joints
were excessively bulky and their electrical
and mechanical performance suffered from
the shortcomings of soldered connections.
The installation of underground distribution
made greater strides as those early connec-
tion methods gave way to specialized prod-
ucts and techniques developed by
BURNDY
®
at the request of, and in close col-
laboration with, engineers of leading utilities.
These specialized connectors were easier
and more economical to install, more com-
pact, and more dependable electrically and
mechanically.
For installation in conjunction with these
connectors, BURNDY
®
also developed prod-
ucts to protect the secondary system from
the effects of fault currents. The continuing
improvement of these products, based on
field experience and laboratory research, is
contributing to even greater dependability
and economy in underground distribution.
Design Objectives in Connectors for
Underground
While each of the principal types of equip-
ment described in the following pages has
been designed to meet particular service
requirements, all have several basic objec-
tives in common:
Reliability:
To minimize outages and their
serious consequences in the high load
density areas served by underground sys-
tems.
Ease of Installation:
Compact for easy
installation in the confined space of a man-
hole and transformer vaults. Mechanical
connections that eliminate difficult solder
joints.
Economy:
By reducing the time and skill
required for installation of a dependable,
insulated compact connection.
Versatility:
For permitting easier changes,
expansion, and additional services with a
minimum of system shutdown.
Figure 1 Radial Secondary Distribution System
Figure 2
K-3
Blue highlighted items are industry standard and most frequently ordered.
US: 1-800-346-4175
www.burndy.com
Canada: 1-800-387-6487
BURNDY
®
Underground