fmtjfw
Senior Member
- Location
- Fairmont, WV, USA
Section/Paragraph: 210.12(A)(3)b. and (4)b.
New Text
210.12 Arc-Fault Circuit-Interrupter Protection.
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(A) Dwelling Units.
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(3) A listed supplemental arc protection circuit breaker installed at the origin of the branch circuit in combination with a listed outlet branch-circuit type arc-fault circuit interrupter installed at the first outlet box on the branch circuit where all of the following conditions are met:
....
b. The maximum length of the branch-circuit wiring from the branch-circuit overcurrent device to the first outlet shall not exceed 15.2 m (50 ft) for a 14 AWG conductor or , 21.3 m (70 ft) for a 12 AWG conductor , or {???} for a 10 AWG conductor.
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(4) A listed outlet branch-circuit type arc-fault circuit interrupter installed at the first outlet on the branch circuit in combination with a listed branch-circuit overcurrent protective device where all of the following conditions are met:
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b. The maximum length of the branch-circuit wiring from the branch-circuit overcurrent device to the first outlet shall not exceed 15.2 m (50 ft) for a 14 AWG conductor or , 21.3 m (70 ft) for a 12 AWG conductor , or {???} for a 10 AWG conductor.
[{???} to be replaced by the appropriate metric and english measures calculated from the formula in the original proposal for this section of the 2014 Code.]
Substantiation
#10 AWG wire is a plausible conductor size for use in a dwelling unit for purposes of meeting reasonable voltage drop goals. Consider #10 Z/kFt = 1.25 Ohms; 125V circuit 3% VD = 3.75 Volts; load current 15 Amperes. 3.75A / 15V = 0.25 Ohms; 0.25 Ohms / 1.25 Ohms/kFt = 0.2; 200 conductor feet or 100 circuit feet. Not implausible for a McMansion.
Inserted Deleted
New Text
210.12 Arc-Fault Circuit-Interrupter Protection.
....
(A) Dwelling Units.
....
(3) A listed supplemental arc protection circuit breaker installed at the origin of the branch circuit in combination with a listed outlet branch-circuit type arc-fault circuit interrupter installed at the first outlet box on the branch circuit where all of the following conditions are met:
....
b. The maximum length of the branch-circuit wiring from the branch-circuit overcurrent device to the first outlet shall not exceed 15.2 m (50 ft) for a 14 AWG conductor or , 21.3 m (70 ft) for a 12 AWG conductor , or {???} for a 10 AWG conductor.
....
(4) A listed outlet branch-circuit type arc-fault circuit interrupter installed at the first outlet on the branch circuit in combination with a listed branch-circuit overcurrent protective device where all of the following conditions are met:
....
b. The maximum length of the branch-circuit wiring from the branch-circuit overcurrent device to the first outlet shall not exceed 15.2 m (50 ft) for a 14 AWG conductor or , 21.3 m (70 ft) for a 12 AWG conductor , or {???} for a 10 AWG conductor.
[{???} to be replaced by the appropriate metric and english measures calculated from the formula in the original proposal for this section of the 2014 Code.]
Substantiation
#10 AWG wire is a plausible conductor size for use in a dwelling unit for purposes of meeting reasonable voltage drop goals. Consider #10 Z/kFt = 1.25 Ohms; 125V circuit 3% VD = 3.75 Volts; load current 15 Amperes. 3.75A / 15V = 0.25 Ohms; 0.25 Ohms / 1.25 Ohms/kFt = 0.2; 200 conductor feet or 100 circuit feet. Not implausible for a McMansion.
Inserted Deleted