nesc subcommittee 5 changes to the 2017 nesc - ieee-sa · pdf filenew edition of asce 7 ... 52...

NESC Subcommittee 5Changes to the 2017 NESC
Joseph Rempe
18 October 2016

Re-format Rule 241.C. At Crossings
2
241. Application of grades of construction to different situations
2012version

3
2012version
2017version

4
2012version
2017version
SameWords
EasiertoComprehend

Grade N
5
CPIntention:
ChangeGradeNEmergency&Temp
EliminateGradeNfromTable242-1

Grade N
6
CPIntention:
ChangeGradeNEmergency&Temp
EliminateGradeNfromTable242-1
FinalModification:
KeepGradeN
AddNOTE toRule240.A.General:NOTE: For emergency or temporary installations,
see Rule 014.

Grade Cx
7
CPIntention:MakeGradeCatcrossingsanofficialGrade:CallitCx
ListinSection24-GradesofConstruction

Grade Cx
8
PotentialModification:EliminateGradeCatcrossings

Grade Cx
9
PotentialModification:EliminateGradeCatcrossings
FinalAction:Rejectanychange

Revise Table 242-1Grades of Construction Applications
10

11
CPIntention:Improvelogicallayoutandformat
Columnssequencefromlowtohighvoltage
Rowssequencefromlowtohighvoltage

12
2012Table242-1

13
2012Table242-1

14
2017 Table242-1

15
2017 Table242-1

16
FN3reversed;highergradeinthetable
3 Grade B C construction shall may be used if the supply circuits will not be promptly de-energized, both initially and following subsequent breaker operations, in the event of a contact with lower supply conductors or other grounded objects.

17
AddFN11 GradeNfordielectricfiber-opticsupplycables

18
Meet Rule 230F1b Insulated Comm Cables in Supply Space
andSupported by effectively grounded messenger
orBonded at intervals specified in Rule 092C to Supply messengers supporting cable meeting Rule 230C1

19
FinalAction:Accept

k-factor
20
Introducedin1941DistrictLoadswerereduced
Clearancesbasedonprevioushigherloads
K-factorapproximatedthesameresultantloadingonthewiretocreatethesamesagsClearancesbasedonsags,nottension
Resultingincreaseintensionnotintendedforstructuraldesign
2007NESCaddedDistrictLoadMaptoSec23

k-factor
21
CPIntention: Setk=0insection25
Onlyaffectsguyedstructures
Iftensionssetat%limit,designtensionsincrease -everydaytensionsincrease
Affectonstructuresconsideredsmall

k-factor
22
CPIntention: Setk=0insection25
Onlyaffectsguyedstructures
Iftensionssetat%limit,designtensionsincrease -everydaytensionsincrease
Affectonstructuresconsideredsmall
FinalAction:Reject
WillcoordinateeffortwithSC4innextcycle

Delete Rule 243.C.4
23

Delete Rule 243.C.4
24
When communication conductors are required tomeet Grade B or C, only the requirements formechanical strength for these grades are required.

Delete Rule 243.C.4
25

Delete Rule 243.C.4
26
Two new grades of construction:Undefined Loads + Grade B StrengthUndefined Loads + Grade C Strength

Delete Rule 243.C.4
27
FinalAction:Accept

Rule 250C: Add Wind Return Period
28

29
NOTE: The commentary to ASCE 7-2005 indicates thatthese wind speeds represent a 50-to-90 year meanrecurrence interval.

30
NOTE: The commentary to ASCE 7-2005 indicates thatthese wind speeds represent a 50-to-90 year meanrecurrence interval.
FinalAction:Accept

Rule 250C: Eliminate 60 ft Exclusion
31

Rule 250C: Eliminate 60 ft Exclusion
32
Forgeeht aboutit!!!!

Non-linear analysis
33
CPIntention:
Rule250BGradeB IncreaseStrengthFactorwhenusenon-linear
Rule250BGradeC DecreaseStrengthFactorwhenuselinear
Rule250C&D .75to.79

Non-linear analysis
34

Non-linear analysis
35
Intention:Rule250BGradeB IncreaseStrengthFactor
whenusenon-linear
Rule250BGradeC DecreaseStrengthFactorwhenuselinear
Rule250C&D .75to.79
AsModifiedin2013:Rule250B ReduceLFfornon-linear
Rule250C&D IncreaseLFforlinear

Non-linear analysis
36

Non-linear analysis
37

Non-linear analysis
38
Furtheranalysisshowedinconsistenciesintheresultsofapplyingthesevalues.
-SomeofGradeCrequirementshigherthanGradeB
-Reducedrequirementsexceedincreased loadduetonon-linear

Non-linear analysis
39
Furtheranalysisshowedinconsistenciesintheresultsofapplyingthesevalues.
-SomeofGradeCrequirementshigherthanGradeB
-Reducedrequirementsexceedincreased loadduetonon-linear
FinalAction:Reject

ClarificationDetermining Gust Response Factor
40

ClarificationDetermining Gust Response Factor
41
ClarifiesusingspanlengthtodetermineGRF
Previouslystatedasdesignwindspan
FinalAction:Accept

Clarify when ice is appliedRule 250D
42

43
Addiceto:WiresConductorsCablesMessengers
Donotaddiceto:StructureOthersupportedfacilities

44
Addiceto:WiresConductorsCablesMessengers
Donotaddiceto:StructureOthersupportedfacilities
FinalAction:Accept

New ASCE ReferenceExtreme Wind Map Figures 250-2
45

46
2012NESC
2017NESC
ASCE7-05MinimumDesignLoadsforBuildingsandOtherStructures
ASCE74-10GuidelinesforElectricalTransmissionLineStructuralLoading

47
SameMap
NewlyrevisedASCEstandard
2012NESC
2017NESC
ASCE74-10GuidelinesforElectricalTransmissionLineStructuralLoading
FinalAction:Accept

New ASCE ReferenceExtreme Ice Map Figures 250-3
48

49
2012NESC
2017NESC

50
2012NESC
2017NESC
SameMap
NewEditionofASCE7
FinalAction:Accept

Longitudinal Capability Rule 252.C.6
51

52
It is recommended that structures having a longitudinal strength capability be provided at reasonable intervals along the line.

53
LongitudinalcapabilityrecommendationmovedtheissuetoaRECOMMENDATION
FinalAction:Accept

Aeolian Vibration Rule 261H.1.b
54

55

56
FinalAction:Accept

57
FinalAction:Accept

Insulators New Rating System
58
OldLinePostratings:
Ratingequaltoaverage
Lowestnolessthan85%ofaverage
NewLinePostratings:
Rating=Minimumofallinsulators

Insulators New Rating System
59
OldTransmissionSuspensionratings:
1.2standarddeviations
NewTransmissionSuspensionratings:
3.0standarddeviations

Exception AddedInsulator Factory Tests Rule 274
60

Exception AddedInsulator Factory Tests Rule 274
61
EXCEPTION:
Guyinsulatorsmanufacturedperdesigns
forwhichvalidationtestshavebeenperformed
and
avalidqualityassurancep

nesc subcommittee 5 changes to the 2017 nesc - ieee-sa · pdf filenew edition of asce 7 ... 52...

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