Chapter 2 Ampacity
Where two different ampacities apply to adjacent portions of a circuit, the higher ampacity shall be permitted to be used beyond the point of transition, a distance equal to 10 feet or ____ percent of the circuit length figured at the higher ampacity, whichever is less.
10%
What os the ampacity of four #4/0THWN copper current carrying conductors in a raceway installed through an ambient temperature of 45˚ C?
150.9 amps
A cable contains seven current-carrying #10 TW conductors in an ambient temperature of 30˚C. What is the ampacity of this conductor?
18.75a
What is the maximum current allowed on a #12 THHN copper conductor in an ambient temperature of 122˚F with a total of six current-carrying conductors in the conduit.
21.6 amps
The ampacity of copper #10 THWN-2 is ____ when there are three conductors in the conduit and the ambient temperature is 70˚F.
41.6 amps
What is the ampacity of each conductor of a group of twenty-five #14 copper RHH conductors all in one conduit with an ambient temperature of 45˚C.
41a
What is the ampacity of 4 #6 THW copper current-carrying conductors enclosed in schedule 80 PVC conduit 8 feet in length entering a trench?
65a
What is the ampacity of a #18 SVE cord with three conductors carrying current in an ambient temperature of 30˚C?
7 amps
A 20" length of conduit that separates two cabinets contains 30 current-carrying conductors, the ambient temperature is 26˚C. These conductors are to be derated ____.
not required
Determine the size of conductors required to supply a 75 amp non-motor load. The device terminations are rated at 75˚C. use copper conductors, conductor insulation type is THHN.
#4
What is the allowable ampacity of a #4 THW in free air in an ambient temperature of 104˚F?
110 amps
Determine the allowable ampacity of 13 - #12 THHN conductors in a raceway, when passing through an area where the ambient temperature is 40˚ C.
13.65a
Three #8 XHHW conductors are installed in a wet location with an ambient temperature of 45˚C. What is the ampacity of the conductor?
141.75a
The ampacity of a #14 THW conductor when there are not more than three conductors in a raceway and the ambient temperature is 36˚C, would be ____ amps.
16 amps
What is the allowable ampacity of a #12 TW copper conductor in a raceways with an ambient temperature of 75˚F?
16.4 amps
A single-phase 240/120 volt service has six #3/0 THW copper conductors in parallel installed in a single raceway. What is the ampacity of each conductor?
160a
What is the ampacity of a #3/0 THWN conductor installed in an ambient temperature of 104˚F?
176a
What is the allowable ampacity of of a #10TW copper conductor is an ambient temperature of 70˚F?
18" conduit is a nipple. 310.15(B3)(a)(2) = NO DEBRATING REQUIRED.
What is the maximum current allowed on a #10 THW when in a conduit with 5 other current-carrying #10 THW's and two bare #10 grounding conductors? (all are copper conductors) (this is a total of 8 conductors in the conduit).
19.68 amps
What is the allowable ampacity of a #2/0 THW aluminum conductor with an ambient temperature of 23˚C.
21a
A raceway contains nine #12 THHN conductors from a 120/240v, a single- phase panelboard. The conductors supply three 120/240v, three-wire circuits made up of L1, L2 and a grounded conductor (neural). What is the allowable ampacity for each of the #12 conductors.
24 amps
A raceway contains two #12 THW conductors. The raceway is installed in an ambient temperature of 115˚F. What is the ampacity of this conductor?
28 amps
The overcurrent protection of a #10 THW conductor, when there are not more than three conductors in a raceway, and the ambient temperature is 28˚C, would be ____ amps.
30 amps
What is the ampacity of each of the four #8 XHHW copper conductors in a conduit above the dropped ceiling on a 4-wire, three-phase wye circuit where the load is all fluorescent lighting?
44a
How many conductors would be counted in a branch circuit raceway for the purpose of derating conductor ampacity given the following: 3 bare conductors - 3 black insulated conductors - 3 white insulated conductors - 3 red insulated conductors The service is a single-phase, the load is balanced on each circuit and there are no harmonic currents on the neutrals.
6
The maximum overcurrent protection of a copper #10 RHW conductor is ____ when there are three conductors in a conduit and the ambient temperature is 104˚F.
9.7875
The source is 3ø208/120v. The load is three banks of fluorescent lights connected line to neutral. The three current carrying conductors and neutral are all in the same conduit. If the line current is 50 amps, what size THWN conductors would be required.
#6 THWN
What is the maximum size 60˚C copper conductor permitted for a 3 ton air-conditioning unit with a load of 25 amps in an ambient temperature of 122˚F?
#6 TW
24 - #12 THW current-carrying conductors are installed in a conduit 18" in length. What is the total derating percent of value?
Maximum over protection is 30A