REFERENCE INDUCTIVE NOISE

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BELL SYSTEM PRACTCES AT&TCo StCindard SECTON 500-12-100 luue 8, January 1973 REFERENCE NDUCTVE NOSE ENERAL 101 This section contains information to control and minimize the effects of inductive noise

nductive noise, as used in this section, is caused by telephone station being within the electromagnetic field of: Power circuits Transformers Neon lights Fluorescent lights Office machines Such

1 BELL SYSTEM PRACTCES AT&TCo StCindard SECTON luue 8, January 1973 REFERENCE NDUCTVE NOSE ENERAL 101 This section contains information to control and minimize the effects of inductive noise at a subscriber station 102 This section is reissued to: Add Fig 2 and 3 Revise Table B Change ringer isolator and telephone set connections Fig 6 and 7 Add note on PA ringer, Fig 4, 5, 8, and nductive noise, as used in this section, is caused by telephone station being within the electromagnetic field of: Power circuits Transformers Neon lights Fluorescent lights Office machines Such fields create foreign voltages on the telephone circuit Unbalance of the telephone circuit will result in noise and low frequency hum and eliminating the cause of high leakage or resistance unbalance may adequately solve the problem 202 The balance-to-ground of the customer station sets is often the controlling factor in the susceptibility to inductive noise Note: The unbalance between the two sides of a line which has only the capacitance afforded by the air dielectric between the tip and ring shall not exceed three volts on the meter at the local testdesk 203 The unbalances due to nongrounded ringers are small and noise resulting from the action of induced voltages on these unbalances is usually negligible 204 When noise is encountered, the steps required for the control of inductive noise (in order of practical application) are: (1) Balance line (2) nstall 3-element tube (3) nstall 4-element tube (4) nstall solid state ringer isolator 205 The 425A and 426A electron tubes are compatable and can be mixed with no adverse effects on the circuit 2 Station apparatus and associated wiring should not be located closer to possible sources of inductive noise than the separations specified in Division 461 sections covering wiring and clearances CONTROL OF NDUCTVE NOSE 201 Poor insulation or resistance unbalance of the telephone circuit contributes to noise resulting from inductive interference Locating 3 STATON RNN BRDES 301 B-type ringers, which are manufactured with magnetic iron core ringer coils, have red-striped markings on both coil covers These red-striped ringers are lower in impedance and increase the susceptibility to inductive noise when used for grounded ringing 302 All low-impedance ringers on grounded ringing lines troubled with inductive noise American Telephone and Telegraph Company, 1973 Printed in USA Page Reissued May 1973 BSP i05_ ljpg Scanned by Frank Harrell, (Cowboy Frank) Castle Rock, Colorado Feb 29, :48:02

SECTON 500-112-100 should be replaced by high-impedance capacitor-type ringing bridges ie C4A type or equivalent 303 When inductive noise is excessive on lines with high-impedance capacitor-type

ringer equipped with a tube or ringer isolator is equivalent to a nongrounded ringer (provided the induced voltage between the line and ground is not high enough to cause conduction of the tube, or

2 SECTON should be replaced by high-impedance capacitor-type ringing bridges ie C4A type or equivalent 303 When inductive noise is excessive on lines with high-impedance capacitor-type grounded ringing bridges, tubes or ringer isolators may be utilized to minimize the effects of the induced voltage 304 From the standpoint of susceptibility to inductive noise, a grounded station ringer equipped with a tube or ringer isolator is equivalent to a nongrounded ringer (provided the induced voltage between the line and ground is not high enough to cause conduction of the tube, or exceed the limits of the ringer isolator, and that tip party identification is not used) 403 The electromagnet associated with 10-cent operation is connected in series with the line n order to minimize the effect of the electromagnet on transmission, a 452A or 452B 4-uf capacitor is connected in parallel with it n areas of low-frequency inductive interference it may be necessary to increase the size of this capacitor to keep the noise pickup within acceptable limits A D Kit of Parts (Fig 1) is available for this purpose and is intended for use in all 200-type coin collectors using a 425- or 4010-type network t replaces the 452A or 452B capacitor 4 MULTSLOT CON STATONS 401 Multislot coin first coin collectors are susceptible to inductive noise in exposed areas Older types of coin first coin collectors have a large shunt unbalance caused by the connection of the coin relay from one side of the line to ground Later types correct this unbalance by use of center-tapped 101B induction coils of 425- or 4010-type networks with the coin relay connected from the center tap (balance point) to ground 402 Where noise problems arise with older type coin collectors, it will be necessary to replace the coin collector with one employing a 425- or 4010-type network The single slot coin telephone sets are much Jess susceptible to inductive noise and should be used in place of multislot coin collectors since they use a ground-lifting relay (in DTF systems) to effectively reduce inductive interference Fig 1-D Kit of Parts 404 The D Kit of Parts will not fit in the 3-slot panel, 235- and 1235-type coin collectors 5 DEVCES TO MNMZE NDUCTVE NOSE 501 Three different electrical devices may be used to minimize the effect of inductive noise where encountered 426-type, 3-element, gas-filed cold cathode electron tube Page 2 Revised May 1973 BSP i05_ jpg Scanned by Frank Harrell, (Cowboy Frank) Castle Rock, Colorado Feb 29, :48:21

SS 8, SECTON 500-112-100 425-type, 4-element, gas-filled cold cathode electron tube Ringer isolator (D-180036 Kit of Parts) 502 Table A shows usage of the tubes, ringer isolator for the various party

operation f a suitable supply is not available, tube equipped sets cannot be used Fig 2--Ringer solator in 500-Type Telephone Set 504 The limitations on the number of tube equipped ringing bridges

the limitations, refer to Section 500-114-100 505 Tube equipped sets may be used on 2-party required lines provided tip-party identification is not 3-Element Tube (42fJType) 506 The 426-type

inductive interference, station ringers should be connected as shown in Fig 4 Fig 3---tRinger solator in 7 4-Type Connecting Block 508 For positive stations on lines experiencing inductive

3 SS 8, SECTON type, 4-element, gas-filled cold cathode electron tube Ringer isolator (D Kit of Parts) 502 Table A shows usage of the tubes, ringer isolator for the various party services 503 Tube equipped sets usually require either superimposed ringing (ac ringing voltage plus a de bias voltage), or a pulsating ringing current, in order to assure satisfactory ringer operation f a suitable supply is not available, tube equipped sets cannot be used Fig 2--Ringer solator in 500-Type Telephone Set 504 The limitations on the number of tube equipped ringing bridges and the permissible loop resistance are more restricted than for regular capacitor-type ringing bridges The reduction in limitations is different for various central office ringing arrangements For the limitations, refer to Section Tube equipped sets may be used on 2-party required lines provided tip-party identification is not 3-Element Tube (42fJType) 506 The 426-type 3-element tube may be added to high-impedance grounded ringers to minimize the effects of inductive noise where encountered - P RNER SOLATOR 507 When 3-element tubes are used to combat inductive interference, station ringers should be connected as shown in Fig 4 Fig 3---tRinger solator in 7 4-Type Connecting Block 508 For positive stations on lines experiencing inductive interference, inducted noise voltages of 20 to 30 volts may be sufficient to cause the control gap to conduct This conduction ("flashover") will result in noise (sputtering) on the line during conversation 509 At negative station, the tube lead is normally connected to tip to put the control Page 3 BSP i05_ jpg Scanned by Frank Harrell, (Cowboy Frank) Castle Rock, Colorado Feb 29, :48:51

SECTON 500-112-100 TABLE A PARTY SERVCES 4-PARTY DEVCE 2PARTY FULL SELECTVE RNN 3-Element Tube 4-Element Tube 4-PARTY 8-PARTY 2PARTY WTH SEMSELECTVE SEMSELECTVE TP PARTY RNN RNN DENTFCATON Ringer

mjlst be connected to ground The main gap will normally withstand 70 to 80 volts of induced noise before "flashover" (conduction) 510 For additional information on the 3-element tube, see Section

4 SECTON TABLE A PARTY SERVCES 4-PARTY DEVCE 2PARTY FULL SELECTVE RNN 3-Element Tube 4-Element Tube 4-PARTY 8-PARTY 2PARTY WTH SEMSELECTVE SEMSELECTVE TP PARTY RNN RNN DENTFCATON Ringer solator gap across the line At stations without AN the lead may be connected to ground if ringer operation is marginal Where negative stations are connected to 96-volt long line circuits, the lead mjlst be connected to ground The main gap will normally withstand 70 to 80 volts of induced noise before "flashover" (conduction) 510 For additional information on the 3-element tube, see Section Eiement Tube (426-Type) 511 The 425-type 4-element tube may be required in cases where the induced voltage on the telephone line exceeds the values for satisfactory operation of the 3-element tube ringing (503) or in grounded ringing arrangements with 96-volt long line circuits where a tube is not required 515 The ringer isolator is intended for use with all grounded ringers where there is a noise problem except those ringers used in 4-party full selective and 8-party semiselective ringing service (Fig 6) The ringer isolator may be used at subscriber stations requiring tip party identification dentification connections are made in the normal manner, but only the 2650-ohm identification circuit should be used The 1000-ohm identification circuit should not be used because excessive noise may be induced on the line One ringer isolator is required for each grounded ringer (Fig 7) 512 The control gap of the 4-element tube is bridged across the line (and the main gap connected between the line and ground) for both positive and negative stations (Fig 5) The line is protected from induced noise by the high breakdown point of the main gap Note: When a station set is equipped with a 425A tube and used with 96-volt dial long line circuit, install a 542K 5uf capacitor (furnished locally) in series with the () tube lead using any spare terminal or D connector 513 For additional information on the 4-element tube see Section Ringer aolstor (D Kit of Psrts) 514 The P-90D011 ringer isolator (furnished with kit) may be used in those cases where the central office is not equipped to provide superimposed Lines equipped with ringer iaolstors csnnot be tested for continuity by conventions/ testdesk procedures This device should be instslled in such s msnner ss not to interfere with electricsl or mechsnicsl operation of the telephone set (Fig 2 snd 3) 516 When the design of the telephone set prohibits mounting either a cold-cathode tube or a ringer isolator, inside the telephone set, use a 74-type connecting block in conjunction with the telephone set for housing either of these devices (refer to Section ) Fig 8 shows AC1 or AD1 telephone base connections using 74A connecting block 517 Table B and (Fig 9) show wiring changes and connections for ringer isolator when used with a AC1 or AD1 telephone base, 4 SSP S i05_1973-0l-04jpg Scanned by Frank Harrell, (Cowboy Frank) Castle Rock, Colorado Feb 29, :49:10

SS 8, SECTON'S00-112-100 511 For additional information on the D-180036 501-375-100 Kit of Parts (ringer isolator) see Section tubes and ringer isolator, the problem must be referred to the proper

BASE FOR RNER SOLATOR (F 9) WRE OR LEAD COLOR REMOVE FROM CONNECT TO CONNECT TO ACl ADl TERM BOARD 74-TYPE CONN BLK Ringer BK L1 3 s B B Note 3 Strap y A Line Switch s A A Mtg Cord A01 Base R y BK w

5 SS 8, SECTON'S For additional information on the D Kit of Parts (ringer isolator) see Section tubes and ringer isolator, the problem must be referred to the proper supervision for other corrective arrangements 519 f situations are encountered where induced voltage exceeds the capabilities of the electron ttable B MODFCATON AND CONNECTONS OF AC1 AND AD1 TRMLNE BASE FOR RNER SOLATOR (F 9) WRE OR LEAD COLOR REMOVE FROM CONNECT TO CONNECT TO ACl ADl TERM BOARD 74-TYPE CONN BLK Ringer BK L1 3 s B B Note 3 Strap y A Line Switch s A A Mtg Cord A01 Base R y BK w R L2 4 L1 5 nside Wire AC1 Base y A BK Rt 3 1 R 4 Ringer 5 solator y 1 BK 2 Ring R 4 Line Wire Tip rd y 5 1 BATT BK 3 nsulate and store t First conductor of second inside wire (quad) Notes: 1 Connections are for tip party reverse tip and ring line wire leads for ring party 2 Use 74 type connecting block for housing ringer isolator and terminating mounting cord or inside wire, disconnect and store 425A electron tube leads 3 Connect to terminal B for tip party identification if current model P1A ringers are used Page 5 BSP S i05_ Sjpg Scanned by Frank Harrell, (Cowboy frank) Castle Rock, Colorado Feb 29, :49:34

'l e NT CO!D DR () < LNE WRE L2 31 TP () r!

1 """", (NOTE 2) L --------, (A) (S-R) B Nl A,MZB,NA Oil PA RNER (S) APPROX 2500ll 1650ll SOOll SOOll "' 0 z - ht!

$STATON NOTES: 426A ELECTRON TUBE (NOTE ) roll TP STATON, REVERS TP AND RN LEADS AT CONNECTN BLK (OR EQUVALENT), 2 \HER$ MUST BE CONNECTED TO ROUND N NSULATE AND STOlt (BL) LEAD REMOVED rron LATER MODEL PA RNERS t D-161488 CONNECTO!

MUST BE CONNECTED TO ROUND N NSULATE AND STOlt (BL) LEAD REMOVED rron LATER MODEL PA RNERS t D-161488 CONNECTO!

6 'l e NT CO!D DR () < LNE WRE L2 31 TP () r!l l ;;: AO :v: w COMMON CATMOOE A, cu RNER 2650ll (S) OOOll NEATVE RN STATON (A) () 426A ELECTRON TUBE (NOTE ) l2 Ll e 1 """", (NOTE 2) L , (A) (S-R) B Nl A,MZB,NA Oil PA RNER (S) APPROX 2500ll 1650ll SOOll SOOll "' 0 z - ht! 8 RN TP AO tw (C) tl i OOOll (S) (A) ll () L2 e t (BL) (S-R) SOOll SOOll 1650ll APPROX 2500ll A CU RNER POSTVE RNCO STATON NOTES: 426A ELECTRON TUBE (NOTE ) roll TP STATON, REVERS TP AND RN LEADS AT CONNECTN BLK (OR EQUVALENT), 2 \HER RNER OPERATON S MARNAL AT STATONS WTHOUT AN, TUBE LEAD NAY & CONNECTED TO ROUND AT STATONS USN 96V LON LN CRCUTS, LEAD MUST BE CONNECTED TO ROUND N NSULATE AND STOlt (BL) LEAD REMOVED rron LATER MODEL PA RNERS t D CONNECTO! OR SPAR[ TERMNAL B Ml AM28,NA OR PA RNER Fig Element Tube, Typical Ringing Bridge Cannectlon BSP i05_ Q6jpg Scanned by Frank Harrell (Cowboy Frank) Castle Rock, Colorado Feb 29, :49:53

$CO OR COliN NTOCOD 'X LNE BLK 011 (S) LNE \lire RN R L2 (S R) CONTROl 265011 100011 L2 (S R)$ NEATVE RN STATON 425A ELECTRON TUB (NOTES ANO 2) RN LZ Tl P () Ll RD 100011 (BL) t (S R) 50011

NEATVE RN STATON 425A ELECTRON TUB (NOTES ANO 2) RN LZ Tl P () Ll RD 100011 (BL) t (S R) 50011

$STATON 425A ELECTRON TUBE ( NOTES AND 2) HEN A STAT ON SET S EQU PPED \lith A 4 L M NT 425A$ LOCALLY) N SERES WTH THE () TUBE LEAD USN ANY SPARE TERMNAL OR 0 161488 CONNECTOR 2 for TP

LOCALLY) N SERES WTH THE () TUBE LEAD USN ANY SPARE TERMNAL OR 0 161488 CONNECTOR 2 for TP

REMOVED FROM LATER MODEL PA RNERS Fig 5--+-Element Tube, TypicD Ringing Bridge ConnediDns BSP

7 CO OR COliN NTOCOD 'X LNE BLK 011 (S) LNE \lire RN R L2 (S R) CONTROl L2 (S R) A''ROX Tl P () () () Ll RO -; A C4A RNER B 141A;N2B,NA OR PA RNER NEATVE RN STATON 425A ELECTRON TUB (NOTES ANO 2) RN LZ Tl P () Ll RD (BL) t (S R) APPROX "' D D NOTES: A C4A Rl NER B 141A,MZB,NA OR PA RNER POS TVE RN STATON 425A ELECTRON TUBE ( NOTES AND 2) HEN A STAT ON SET S EQU PPED \lith A 4 L M NT 425A ELECTRON TUBE AND USED WTH 96 VOLT DAL LON LNE CRCUT,NSTALL A 54ZK CAPACTOR 5Uf (furn SHED LOCALLY) N SERES WTH THE () TUBE LEAD USN ANY SPARE TERMNAL OR CONNECTOR 2 for TP STATON, REVERSE TP AND RN LEADS AT CONNECT N BLK(OR EQU VALENT) NUSLAT AND STORE t ( 8L) LEAD REMOVED FROM LATER MODEL PA RNERS Fig 5--+-Element Tube, TypicD Ringing Bridge ConnediDns BSP S i05_ jpg Scanned by Frank Harrell, (Cowboy Frank) Castle Rock, Colorado Feb 29, :50:14

SECTON 500-112-100 TYPCAL TELEPHONE SET CONNECTON ll LEAD DESNATON RNER AND TEL SET CONNECTONS RN L2 TP Ll Rl 130K R2 OK CR2 RD

CONNECTN BLOCK (OR EQUVALENT) t USE SPARE TELEPHONE SET TERMNAL OR D-161488 CONNECTOR Fig lunger solator, Typical Ringing Bridge

8 SECTON TYPCAL TELEPHONE SET CONNECTON ll LEAD DESNATON RNER AND TEL SET CONNECTONS RN L2 TP Ll Rl 130K R2 OK CR2 RD K t'i A S-R 2650ll R ls OODll {BK) C4A RNER t R4 OK R R K C2 co RN STATON FOR TP STATON REVERSE TP AND RN LEADS AT CONNECTN BLOCK (OR EQUVALENT) t USE SPARE TELEPHONE SET TERMNAL OR D CONNECTOR Fig lunger solator, Typical Ringing Bridge Cannedlons f Page 8 SSP S i05_1973-0l-08jpg Scanned by Frank Harrell, (Cowboy Frank) Castle Rock, Colorado Feb 29, :50:33

$': : ]@ SNAL 1 ;:,1,;,\r, :,!$

9 SS 8, SECTON LEAD OES t RNER AND TEL SET CONNECTONS (OFF HOOK) TP () -t K t% - < RN RD il w } t } 1 (S R) f% (BR) w () i (W) (BL) (BL OR (S) (8K) f!j ) DP C4A RNER 26!': : ]@ SNAL 1 ;:,1,;,\r, :,! ff () RNER SOLATOR Rl 130K CR R4 OK C2 005 R3 OK R2 B2K R5 OK M - 0-/61488 CONNECTOR DP-DAL PULSE LS -LNE SWTCH Fig 7----alnger solator, Typical Cannedions for Tip Party dentification Ohms Page 9 BSP S i05_1973-Ql-{)9jpg Scanned by Frank Harrell, (Cowboy Frank) Castle Rock, Colorado Feb 29, :50:

-- SECTON 500-112-100 NEATVE RN PARTY DAL LHT TRNSF NSDE WRE RNQ 7U CONNECTN B LOCK WTH 425A TUBE!

$t-------0'--------------------7 : (BK 11 82,00011 (Y ) (W (Y [Rl t TVE [ :: R _:: N :: :_--jfi---+--{ 5 = ( B ::: =K= ) =: ------ )>--' "- ( R :_ --l! \'l -----<0L PAR:Y ::: ) Y ()!$

10 -- SECTON NEATVE RN PARTY DAL LHT TRNSF NSDE WRE RNQ 7U CONNECTN B LOCK WTH 425A TUBE!NOTE 41 ( Y) ----') 5 [-----j -----{ > () [ tt-- ---t r Tl P RD MOUNTN CORD OR NSO WR CONNECTONS (NOTE Y!W (R ii!t ' : (BK 11 82,00011 (Y ) (W (Y [Rl t TVE [ :: R _:: N :: :_--jfi---+--{ 5 = ( B ::: =K= ) =: )>--' "- ( R :_ --l! \'l -----<0L PAR:Y ::: ) Y ()!W (W) (R] 1 TERMNAL BOARD (NOTE 21 Ll B 0 2 (BK PA RNER R) APPRO X (S-R A ( ) -MOUNTN CORD CONDUCTORS ( ) - NSDE WRE CONDUCTORS - NSULATE ANO STORE -FOR T1 P STA T1 ON-REVERSE RN AND TP LEADS AT 74A CONNECTN BlOCK t - [Rl CONDUCTOR OF SECOND QUAD D NSDE WRE - BASES MANUFACrURED PROR TO 10/t/72 'n - ( Bll LEAD NOT PROV O D ON CURREHT POOUCTCH OOElS NOTES: FVE CONDU CTORS REQURED BETWEEN 74A CONNECTN BLOCK AND TELEPHONE SET USE ONE OUAO AND RED OR TWO TRPLES WTH AC BASE 2 DSCONNECT ls LNE SWTCH LEAD FROM A OF TERMNAL BOARD, NSULATE AND STORE 3 TP PARTY DENTFCATiONS CANNOT BE FURNSHED WTH THESE CONNECTONS 4 WHEN A STATON SET S EQUPPED WTH A 4-ELEMENT 425A ELECTRON TUBE AND USED WTH 96 VOLT DAL LON UNE CRCUT, < STALL A 542K CAPACTOR 5 UF (FURNSHED LOCALLYN SERES WTH THE TUBE LEAD USN ANY SPARE TERMNAL OR CONNECTOR Fig l---t74a Connedlng Block and Ringer Circuit n AC1 and AD1 Telephone 8a1e-<:onnedion1 for Extreme lndudance lnter'ferenc Page 10 SSP S i05_1973-0l-10jpg Scanned by Frank Harrell, (Cowboy Frank) Castle Rock, Colorado Feb 29, :51:15

SS 8, SECTON 500-112-100 NOTES: LNE WRE (NOH mj RN RD ) (t;) (R ) >l (Y ) f R4 OK RNER SOLATO Rl look 25 CR i :! CRZ R5 OK C2 b,: 005 (t;) (R! ira FflltNRWMMLW, lt =iw!

TP PARTY DENTFCATON ON EARLY MODEL PA RNERS 4, FVE CONDUCTORS REQURED BETWEEN 74A CONNECTN BLOCK AND TELEPHONE BASEUSE TWO NSDE WRES ONE QUAD AND ONE PARED OR TWO TRP LESCOLOR CODES ON LEFT SDE ARE

11 SS 8, SECTON NOTES: LNE WRE (NOH mj RN RD ) (t;) (R ) >l (Y ) f R4 OK RNER SOLATO Rl look 25 CR i :! CRZ R5 OK C2 b,: 005 (t;) (R! ira FflltNRWMMLW, lt =iw!w'awb 5 BK Z CONNECTONS SHOWN ARE FOR TP PARTY REVERSE TP AND RN FOR RN PARTY SERVCE PA RNER Z LEADS FOR DAL ll HT CAN BE CONNECTED 0 RECTL Y TO TERMNAL BOARD ON AC TELEPHONE BASE 3 CONNECT ONLY FOR TP PARTY DENTFCATON ON EARLY MODEL PA RNERS 4, FVE CONDUCTORS REQURED BETWEEN 74A CONNECTN BLOCK AND TELEPHONE BASEUSE TWO NSDE WRES ONE QUAD AND ONE PARED OR TWO TRP LESCOLOR CODES ON LEFT SDE ARE FOR l 05AL MT CORD RZ OR NSDE WRE 8ZK (NOTE 4) >; ( ) t '"" li g Jl l(s-r) l(s) APPRO X SOOQ R (W) Rit BK Y ( BL) 1 (BK ) SOOil 05AL MT CORD AND COLOR CODES ON RHT SDE ARE FOR NSDE WRE ll NSULATE AND STORE [ l EARLY MODEL 1 FRST CONDUCTOR OF S&COND NSDE WRE QUAD CURRENT MODEL ' BLLEAD REMOVED FROM CURRENT MODEL PA RNERS CONNECT (5) LEAD TO 8 ON TERMNAL BOARD ONLY F TP PARTY DENTFCATON S REQURED :: 3)- 1iJ :!:; Fig 9--74A Conneding Block and Ringer solator Connedions with AC1 or AD1 Telephone Base Page Pages Revised May 1973 SSP i05_ lljpg Scanned by Frank Harrell, (Cowboy Frank) Castle Rock, Colorado feb 29, :51:38

TELEPHONE SETS 881A102, , 881C102, 881A103, , 881C103, 881A104, , AND 881C104

TELEPHONE SETS 881A102, , 881C102, 881A103, , 881C103, 881A104, , AND 881C104 BELL SYSTEM PRACTCES AT & TCo Standard SECTON 53-2-18 ssue 3, January 1978 TELEPHONE SETS 881A12, 881812, 881C12, 881A13, 881813, 881C13, 881A14, 881814, AND 881C14 1. GENERAL 1.1 This section provides