Installation - Bell System Practices 851 Identification, Installation, Connections, And Maintenance

• An access hole is provided in the P1-type
ringer for ringer bias spring adjustment.
Refer to Section 501-259-101.
rig. 3-Early Version 851-Type Telephone Set Base
(Housing Removed)
Fig. 4-Early Version 2851-Type Telephone Set Base
(Housing Removed)
ISS 8, SECTION 503-601-101
3. INSTALLATION
3.01
When mounting the 851- or 2851-type
telephone set, select a location which provides
at least 6 inches of clearance on all sides to permit
removal of the handset, and for maintenance.
3.02
The telephone set should be mounted before
installing the modular items. To expose
the mounting holes, the hinged chassis assembly
must be lowered by loosening the captive screws
(Fig. 10) holding the top of the chassis. For ease
of installation the chassis assembly can be removed
from the base pan by springing the hinged brackets
sufficiently to clear the pins. The base pan can
then be mounted directly to the wall using the
keyhole slots, or holes provided for mounting over
an electrical outlet box.
Caution: A void damage to wall or
telephone set whenever chassis is in
lowered position.
3.03
All sets except the CM codes can be wired
using either inside wiring cable or connector
cable. When mounted over an outlet box, bring
wiring through opening in base pan before mounting.
When exposed, bring wiring up from bottom (right
side of handset cord jack). Allow 20-22 inches of
cable inside set for routing and terminating.
3.04
With wiring brought into set and base pan
mounted, replace chassis assembly if previously
removed, but leave in lowered position.
3.05
Where IW cable is used, prepare and route
as follows.
(1) Remove sheath to surface of outlet box or
bottom of hole in base pan, depending on
method of wiring.
(2) Remove cable clamps. Pinch legs of clamp
from front of chassis (Fig. 13).
(3) Slip one of the clamps provided with set
around conductors approximately 9 inches
from end of sheath. Add second clamp 2 inches
above first.
(4) Form slack loop as shown in Fig. 7 or 8
and install first clamp in hole to left of cord
jack.
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