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8-5
INSTALLATION-WIRING DIAGRAMS
SECTION 100-816-208
MARCH 1993
FIGURE 8-1
SECONDARY 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
208 218
207 217
206
216
205 215
204 214
203 213
202
212
201 211
200 210
220 230
231221
222
232
223
233
224
234
225
235
226 236
237
227
228
238
229 239
249
NT1
AC
248
247
257
256
246
245
255
254
244
253
243
242 252
241 251
240
250