user manual

ND-20292
CHAPTER 2
APRIL, 1990
which could cause a hazard to personnel or to the
proper functioning of the equipment.
D. Heat and humidity must be within the limits
provided in Section 220.13 of this document.
E. Although its virtually noiseless operation allows a
wide selection of installation sites, care should be
taken that CCU(s) do not present a hazard to office
traffic. For purposes of economy a central location
to minimize cabling is often used.
230.5 MDF CONSTRUCTION
The Main Distribution Frame (MD!?) consists of two
different types of standard quick-connect terminal
blocks, which are to be mounted onto the 3/4” plywood
backboard. For the sake of neatness and ease of access,
it is also recommended that the blocks be mounted on
appropriate standoffs. The recommended blocks are;
the 66B50 type, for termination of the CCU J cables,
and the 66M50 type, for termination of the station
cables.
The Intermediate Distribution Frame (IDF) requires
only the 66M50 type blocks.
Both the MDF and the IDF utilize standard bridging
clips for each type terminal block. The bridging clips
are used to mate the left half of the terminal block
(terminated cable run) to the right half of the terminal
block (cross connection wire). The bridging clips are
also useful during trouble shooting to help isolate the
cable runs and terminals/telephones from the central
equipment and the Central Office Network from the
system.
Refer to Figure 200-7 for a suggested MDF layout.
Refer to Section 240 of this document for CCU wall
mounting.
230.6 CCU CABLES
Each CCU is equipped with three 50 pin, female
amphenol type connectors. These connectors are
designated Jl to 53. Since each CCU uses the same
designations for the J connectors, it is recommended
that the MDF terminal blocks be labeled with the CCU
number as well as the connector number; for example:
lJ1,2Jl, 351,451,152, etc.
230.7 OUTSIDE LINES
A. The FCC authorized connector for the connection of
CO lines is an RJZlX. The CO lines will be
connected in sequence within this termination
block. Therefore, the lines must be ordered in the
appearance order best suited to the customer’s
usage.
I
Basic
ecu
I
66B50 66M50
TYPE
TYPE
TELCO
RJ2lX
.-.:
A’
Figure 200-7
Typical Full MDF Layout
B. Table 200-16 provides complete information about
the 50 position connector, showing pin number,
lead function, running cable color, and circuit
designation.
C. Ground start and/or Loop start, loop dial DID, 2
and 4 wire E&M Tie lines (types I and V) can be
connected to this system. It is recommended that
only twisted pair wiring be used to cross connect
the lines from the RJ2lX termination block to the
MDF. Refer to Table 200-16 for proper connection
identification.
D. HALF-TAPPING or PARALLEL
CONNECTIONS MUST NOT be used on outside
lines connected to the Electra Mark11 System. This
practice generally results in system malfunctions
on the outside lines.
E. Table 200-16 includes termination of PT and PR
designations, for the Power Failure Transfer
feature. Cross connection between a CO tip (T) and
ring (R) and an SLI-EB ETUs PT and PR, provides
power failure transfer to a Single Line Telephone
installed within the system.
230.8 STATION EQUIPMENT
A. When connecting Multiline Terminals, DSS/BLF
Consoles, or CO Add-On Modules to the MDF, or
IDF, individually twisted two pair cabling must be
used.
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200 - 16