8-5
INSTALLATION-WIRING DIAGRAMS
SECTION 100-816-208

MARCH 1993

FIGURE 8-1SECONDARY PROTECTOR DIAGRAM
IMPORTANT!

To protect against transient voltages and currents, secondary protectors must be installed if

there is outside wiring (Figure 8-1). These protectors, which contain fast semiconductors in

addition to fuses, shall comply with the requirements for secondary protectors for communication

circuits, UL 497A. As of October 1, 1990, the following manufacturers offer secondary

protectors that are UL listed.

QSTU
PESU
KSTU
PSTU
BUILDING #1 BUILDING #2
DK8 KSU
DK16 KSU
BASE UNIT
KCDU
PCOU
QCDU
HESB
DIGITAL OR
ELECTRONIC
TELEPHONE
DIGITAL OR
ELECTRONIC
TELEPHONE
STANDARD
TELEPHONE
OR OTHER
DEVICE
MDFB
CO LINE
Secondary protectors
DDCB
DK8 KSU
DK16 KSU
BASE UNIT
QCDU
PDKU
PEKU
PESU
KCDU
DSS
CONSOLE
(DK16 only)
219209
208218
207217
206216
205215
204214
203213
202212
201211
200210 220230
231221
222232
223233
224234
225235
226236
237
227
228238
229239 249NT1
AC
248
247257
256
246
245255
254
244
253
243
242252
241251
240250