standards and guidelines for communication sites - Radio And ...

More documents

Recommendations

Info

DISSIMILAR METALS AND CORROSION CONTROL CHAPTER 4: EXTERNAL GROUNDING (EARTHING) TABLE 4-4 TOWER GROUND BUS BAR SPECIFICATIONS Item Specification Material Bare, solid Alloy 110 (99.9%) copper bus bar or plate of one piece construction. Should be tin-plated if installing on a galvanized tower. (See “Dissimilar Metals and Corrosion Control” on page 4-34 for information regarding tower corrosion related to copper bus bars.) Minimum Dimensions (ANSI-J-STD-607-A-2002 and NFPA 70-2005, Article 250.64) Mounting brackets Stainless steel Height: 51 mm (2 in.) Thickness:6.35 mm (0.25 in.) Length: Variable to meet the application requirements and allow for future growth. 305 mm (12 in.) is recommended as the minimum length. Conductor mounting holes Number dependent on number of conductors to be attached Holes to be 11 mm (0.4375 in.) minimum on 19 mm (0.75 in.) centers to permit the convenient use of two-hole lugs. Method of attachment of grounding electrode conductor Exothermic welding Irreversible crimp connection 4.5 DISSIMILAR METALS AND CORROSION CONTROL Although the type of metals used in a grounding (earthing) electrode system do not affect the resistance to earth of the grounding electrode system, consideration should be given to select a metal that is resistance to corrosion in the type of soil in which it will be installed. The two areas that should be considered regarding the corrosion resistance of a metal are the compatibility with the soil itself and possible galvanic corrosion effects when it is electrically connected to neighboring metals at the site. (BS 7430:1998) 4.5.1 CORROSION RELATED TO SOIL TYPE The compatibility of a metal with soil is determined by the chemical composition of the soil. The chemical composition factors associated with the corrosion of metals in contact with the soil are as follows: acidity or alkalinity (pH), salt content, soil porosity (aeration), and the presence of anaerobic bacteria. (BS 7430:1998 and TIA/EIA-222-F-R2003) The following list gives a general representation of the aggressiveness of soils, listed in order of increasing aggressiveness (BS 7430:1998): • Gravelly soils (Least Aggressive) • Sandy soils • Silty soils (loam) • Clays • Peat and other organic soils • Made up soils containing cinders (Most Aggressive) 4-34 68P81089E50-B 9/1/05
STANDARDS AND GUIDELINES FOR COMMUNICATION SITES DISSIMILAR METALS AND CORROSION CONTROL The least aggressive soils tend to be those having a high resistivity. The resistivity of soil can be measured, which provides an indication of corrosiveness under aerated conditions (BS 7430:1998). See “Performing Soil Resistivity Test” on page B-6 for measurement details. Soil with a resistivity below 2,000 ohm centimeters (Ω·cm) is generally considered to be highly corrosive (TIA/EIA-222-F-R2003). More details about the aggressiveness of soils can be obtained by measuring the redox (from the words reduction and oxidation) potential of the soil, which indicates the risk of corrosion due to the presence of anaerobic bacteria (BS 7430:1998). Test equipment required to measure redox potential is commercially available. The procedure required to test the redox potential can be found in ISO 11271:2002(E). A geotechnical firm may be required to measure the redox potential of the soil. General guidance on the corrosiveness of some grounding electrode system metals in relation to soil composition is given below in Table 4-5 (BS 7430:1998). A geotechnical firm may be required to determine all of the listed soil parameters. TABLE 4-5 CORROSION RESISTANCE PROPERTIES OF COMMON GROUNDING ELECTRODE SYSTEM METALS AS RELATED TO SOIL COMPOSITION Soil Parameter Grounding Electrode Metal Copper Galvanized Steel Austenitic Stainless Steel* < 700 Slightly Reduced Moderately Reduced Slightly Reduced Resistivity (Ω·cm) 700 to 4000 Slightly Reduced Moderately Reduced Generally Unaffected > 4000 Generally Unaffected Generally Unaffected Generally Unaffected < 200 Moderately Reduced Considerably Reduced Moderately Reduced Redox Potential (mV) 200 to 400 Slightly Reduced Slightly Reduced Generally Unaffected > 400 Generally Unaffected Generally Unaffected Generally Unaffected < 10 Generally Unaffected Generally Unaffected Generally Unaffected Moisture Content (%) 10 to 80 Slightly Reduced Moderately Reduced Slightly Reduced Dissolved > 80 Slightly Reduced Slightly Reduced Slightly Reduced Salts Moderately Reduced Moderately Reduced Slightly Reduced Chlorides Moderately Reduced Moderately Reduced Moderately Reduced pH Acidic < 6 Moderately Reduced Considerably Reduced Slightly Reduced Neutral 6 to 8 Generally Unaffected Generally Unaffected Generally Unaffected Alkaline > 8 Slightly Reduced Moderately Reduced Generally Unaffected Organic Acids > 8 Considerably Reduced Moderately Reduced Slightly Reduced * Austenitic stainless steel shall be formed from 18% chromium and 8% nickel (18/8 stainless steel), per UL 467-2004, section 9.2.6. Table based on information from BS 7430:1998. 68P81089E50-B 9/1/05 4-35
Page 1 and 2:
© 2005 MOTOROLA, INC. ALL RIGHTS R
Page 3 and 4:
TABLE OF CONTENTS Chapter 1. Introd
Page 5 and 6:
STANDARDS AND GUIDELINES FOR COMMUN
Page 7 and 8:
Page 9 and 10:
Page 11 and 12:
Page 13 and 14:
CHAPTER 1 INTRODUCTION 1 This manua
Page 15 and 16:
Page 17 and 18:
Page 19 and 20:
Page 21 and 22:
Page 23 and 24:
Page 25 and 26:
Page 27 and 28:
Page 29 and 30:
Page 31 and 32:
Page 33 and 34:
Page 35 and 36:
CHAPTER 2 SITE DESIGN AND DEVELOPME
Page 37 and 38:
Page 39 and 40:
Page 41 and 42:
Page 43 and 44:
Page 45 and 46:
Page 47 and 48:
Page 49 and 50:
Page 51 and 52:
Page 53 and 54:
Page 55 and 56:
Page 57 and 58:
Page 59 and 60:
Page 61 and 62:
Page 63 and 64:
CHAPTER 3 COMMUNICATION SITE BUILDI
Page 65 and 66:
Page 67 and 68:
Page 69 and 70:
Page 71 and 72:
Page 73 and 74:
Page 75 and 76:
Page 77 and 78: STANDARDS AND GUIDELINES FOR COMMUN
Page 95 and 96: CHAPTER 4 EXTERNAL GROUNDING (EARTH
Page 127: STANDARDS AND GUIDELINES FOR COMMUN
Page 179 and 180:
Page 181 and 182:
Page 183 and 184:
Page 185 and 186:
Page 187 and 188:
Page 189 and 190:
Page 191 and 192:
Page 193 and 194:
Page 195 and 196:
CHAPTER 5 INTERNAL GROUNDING (EARTH
Page 197 and 198:
Page 199 and 200:
Page 201 and 202:
Page 203 and 204:
Page 205 and 206:
Page 207 and 208:
Page 209 and 210:
Page 211 and 212:
Page 213 and 214:
Page 215 and 216:
Page 217 and 218:
Page 219 and 220:
Page 221 and 222:
Page 223 and 224:
Page 225 and 226:
Page 227 and 228:
Page 229 and 230:
Page 231 and 232:
Page 233 and 234:
Page 235 and 236:
Page 237 and 238:
Page 239 and 240:
Page 241 and 242:
Page 243 and 244:
Page 245 and 246:
Page 247 and 248:
Page 249 and 250:
Page 251 and 252:
Page 253 and 254:
Page 255 and 256:
Page 257 and 258:
Page 259 and 260:
Page 261 and 262:
Page 263 and 264:
Page 265 and 266:
Page 267 and 268:
CHAPTER 6 POWER SOURCES 6 6.1 LOCKO
Page 269 and 270:
Page 271 and 272:
Page 273 and 274:
Page 275 and 276:
Page 277 and 278:
Page 279 and 280:
Page 281 and 282:
Page 283 and 284:
Page 285 and 286:
Page 287 and 288:
Page 289 and 290:
Page 291 and 292:
Page 293 and 294:
Page 295 and 296:
Page 297 and 298:
Page 299 and 300:
Page 301 and 302:
Page 303 and 304:
Page 305 and 306:
Page 307 and 308:
Page 309 and 310:
Page 311 and 312:
CHAPTER 7 SURGE PROTECTIVE DEVICES
Page 313 and 314:
Page 315 and 316:
Page 317 and 318:
Page 319 and 320:
Page 321 and 322:
Page 323 and 324:
Page 325 and 326:
Page 327 and 328:
Page 329 and 330:
Page 331 and 332:
Page 333 and 334:
Page 335 and 336:
Page 337 and 338:
Page 339 and 340:
Page 341 and 342:
Page 343 and 344:
Page 345 and 346:
Page 347 and 348:
Page 349 and 350:
Page 351 and 352:
Page 353 and 354:
Page 355 and 356:
Page 357 and 358:
Page 359 and 360:
Page 361 and 362:
Page 363 and 364:
CHAPTER 8 MINIMIZING SITE INTERFERE
Page 365 and 366:
Page 367 and 368:
Page 369 and 370:
Page 371 and 372:
Page 373 and 374:
CHAPTER 9 EQUIPMENT INSTALLATION 9
Page 375 and 376:
Page 377 and 378:
Page 379 and 380:
Page 381 and 382:
Page 383 and 384:
Page 385 and 386:
Page 387 and 388:
Page 389 and 390:
Page 391 and 392:
Page 393 and 394:
Page 395 and 396:
Page 397 and 398:
Page 399 and 400:
Page 401 and 402:
Page 403 and 404:
Page 405 and 406:
APPENDIX A ELECTROMAGNETIC ENERGY I
Page 407 and 408:
Page 409 and 410:
Page 411 and 412:
Page 413 and 414:
Page 415 and 416:
Page 417 and 418:
Page 419 and 420:
Page 421 and 422:
Page 423 and 424:
Page 425 and 426:
Page 427 and 428:
Page 429 and 430:
Page 431 and 432:
Page 433 and 434:
APPENDIX B SOIL RESISTIVITY MEASURE
Page 435 and 436:
Page 437 and 438:
Page 439 and 440:
Page 441 and 442:
Page 443 and 444:
Page 445 and 446:
Page 447 and 448:
Page 449 and 450:
Page 451 and 452:
Page 453 and 454:
Page 455 and 456:
Page 457 and 458:
Page 459 and 460:
Page 461 and 462:
Page 463 and 464:
Page 465 and 466:
Page 467 and 468:
APPENDIX C PROTECTING AGAINST ELECT
Page 469 and 470:
Page 471 and 472:
APPENDIX D GROUNDING (EARTHING) ELE
Page 473 and 474:
Page 475 and 476:
Page 477 and 478:
Page 479 and 480:
Page 481 and 482:
Page 483 and 484:
Page 485 and 486:
Page 487 and 488:
Page 489 and 490:
Page 491 and 492:
Page 493 and 494:
Page 495 and 496:
Page 497 and 498:
APPENDIX E GENERAL CONVERSIONS AND
Page 499 and 500:
Page 501 and 502:
Page 503 and 504:
APPENDIX F R56 COMPLIANCE CHECKLIST
Page 505 and 506:
Page 507 and 508:
Page 509 and 510:
I NDEX Index Index AC power cabling
Page 511 and 512:
Page 513 and 514:
Page 515 and 516:
Page 517 and 518:
show all

standards and guidelines for communication sites - Radio And ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?