26401 Load Calculations - Feeders and Services Exam with
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precise detailed solutions || ||
What is the minimum demand required for the portion of a feeder that supplies 30' of show
|| || || || || || || || || || || || || || || || ||
windows?
6,000 VA ||
5,400 VA ||
3,000 VA ||
2,700 VA - ✔✔ft x va = va || || || || || || ||
30ft x 200VA = 6,000VA
|| || || ||
NEC 220.14(C)(2) ||
At 200 Volt-amperes per linear 300 mm (1 ft) of show window
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Feeder conductor size is adjusted when? || || || || ||
The load supplied is a continuous-duty load.
|| || || || || ||
More than three current-carrying conductors are in a raceway.
|| || || || || || || ||
The ambient temperature surrounding conductors exceeds temperature ratings.
|| || || || || || ||
Voltage drop exceeds 3% for feeders or 5% for the combination of the feeder and branch
|| || || || || || || || || || || || || || || ||
circuit.
All of the above - ✔✔All of those above
|| || || || || || || ||
Using the 25' tap rule, what is the minimum size copper THWN conductor required for a tap
|| || || || || || || || || || || || || || || || ||
from a 400A, 480V, 3Phase feeder?
|| || || || ||
1/0
2/0
No. 1 ||
, No. 2 - ✔✔1/0 || || ||
Switchboard - ✔✔A large single panel, frame, or assembly of panels on which are mounted
|| || || || || || || || || || || || || || ||
on the face, back, or both, switches, overcurrent and other protective devices, buses, and
|| || || || || || || || || || || || || ||
usually instruments. Switchboards are generally accessible from the rears well as from the
|| || || || || || || || || || || || ||
front and are not intended to be installed in cabinets.
|| || || || || || || || ||
What is the minimum general lighting load in VA per square foot, required by the NEC for a
|| || || || || || || || || || || || || || || || || ||
single family dwelling? || ||
3
3-1/2
1
2 - ✔✔3
|| ||
Building - ✔✔A structure that stands alone or that is separated from adjoining structures by
|| || || || || || || || || || || || || || ||
firewalls.
What is the minimum ampacity for a feeder serving two (2) motors at 15HP, one (1) motor at
|| || || || || || || || || || || || || || || || || ||
25HP, and one (1) motor at 40HP? All motors are rated at 480V, 3 Phase.
|| || || || || || || || || || || || || ||
141 Amperes ||
153 Amperes ||
100 Amperes ||
128 Amperes - ✔✔141 Amperes
|| || || ||
When calculating the feeder load for a motor control center supplying several motors, which
|| || || || || || || || || || || || || ||
of the following statements is correct?
|| || || || ||
Determine the sum of all motor loads plus 25% of the largest motor. || || || || || || || || || || || ||
Determine the sum of all motor loads plus 125% of the largest motor.|| || || || || || || || || || || ||
|| || || || || || || || ||
precise detailed solutions || ||
What is the minimum demand required for the portion of a feeder that supplies 30' of show
|| || || || || || || || || || || || || || || || ||
windows?
6,000 VA ||
5,400 VA ||
3,000 VA ||
2,700 VA - ✔✔ft x va = va || || || || || || ||
30ft x 200VA = 6,000VA
|| || || ||
NEC 220.14(C)(2) ||
At 200 Volt-amperes per linear 300 mm (1 ft) of show window
|| || || || || || || || || || ||
Feeder conductor size is adjusted when? || || || || ||
The load supplied is a continuous-duty load.
|| || || || || ||
More than three current-carrying conductors are in a raceway.
|| || || || || || || ||
The ambient temperature surrounding conductors exceeds temperature ratings.
|| || || || || || ||
Voltage drop exceeds 3% for feeders or 5% for the combination of the feeder and branch
|| || || || || || || || || || || || || || || ||
circuit.
All of the above - ✔✔All of those above
|| || || || || || || ||
Using the 25' tap rule, what is the minimum size copper THWN conductor required for a tap
|| || || || || || || || || || || || || || || || ||
from a 400A, 480V, 3Phase feeder?
|| || || || ||
1/0
2/0
No. 1 ||
, No. 2 - ✔✔1/0 || || ||
Switchboard - ✔✔A large single panel, frame, or assembly of panels on which are mounted
|| || || || || || || || || || || || || || ||
on the face, back, or both, switches, overcurrent and other protective devices, buses, and
|| || || || || || || || || || || || || ||
usually instruments. Switchboards are generally accessible from the rears well as from the
|| || || || || || || || || || || || ||
front and are not intended to be installed in cabinets.
|| || || || || || || || ||
What is the minimum general lighting load in VA per square foot, required by the NEC for a
|| || || || || || || || || || || || || || || || || ||
single family dwelling? || ||
3
3-1/2
1
2 - ✔✔3
|| ||
Building - ✔✔A structure that stands alone or that is separated from adjoining structures by
|| || || || || || || || || || || || || || ||
firewalls.
What is the minimum ampacity for a feeder serving two (2) motors at 15HP, one (1) motor at
|| || || || || || || || || || || || || || || || || ||
25HP, and one (1) motor at 40HP? All motors are rated at 480V, 3 Phase.
|| || || || || || || || || || || || || ||
141 Amperes ||
153 Amperes ||
100 Amperes ||
128 Amperes - ✔✔141 Amperes
|| || || ||
When calculating the feeder load for a motor control center supplying several motors, which
|| || || || || || || || || || || || || ||
of the following statements is correct?
|| || || || ||
Determine the sum of all motor loads plus 25% of the largest motor. || || || || || || || || || || || ||
Determine the sum of all motor loads plus 125% of the largest motor.|| || || || || || || || || || || ||
