Question 31
Which condition requires derating of conductor ampacity according to many US electrical code tables?
Question 32
A three-phase, 208 V, 30 A feeder in EMT contains four current-carrying conductors and one equipment grounding conductor. Due to additional circuits, there will now be eight current-carrying conductors in the same raceway. What must the electrician do regarding conductor ampacity?
Question 33
On a large feeder run, ambient temperature in the mechanical room is significantly higher than usual. How does this affect the ampacity of the conductors?
Question 34
When more than three current-carrying conductors are installed together in a conduit, what is a typical requirement regarding their allowable ampacity?
Question 35
Which factor must be considered when calculating the allowable ampacity of conductors installed in a wireway (a type of metal trough used for conductors)?
Question 36
When conductors are bundled in a cable tray and the number of current-carrying conductors is 7, what is the required ampacity adjustment factor, assuming the conductors are all the same size and type?
Question 37
In a $120\text{ V}$ commercial service with a 4-wire Wye system, what is the maximum number of current-carrying $12 \text{ AWG}$ THHN conductors permitted in a $1/2\text{-inch}$ EMT run before ampacity derating is required?
Question 38
In a large open office space, multiple 120 V lighting circuits are run in a single conduit. Which factor must be considered regarding ampacity of the conductors?
Question 39
In a commercial building, a feeder supplies a panelboard with a calculated load of 80 A. The feeder is protected by a 100 A breaker. Which is the best reason for selecting a conductor ampacity above 80 A?
Question 40
A feeder consists of three 2/0 AWG copper ungrounded conductors and one 2/0 AWG neutral in EMT. Due to added circuits, there will now be six current-carrying conductors in the raceway. How does this affect conductor ampacity?
Question 41
Which statement describes a conductor made of aluminum compared to copper of the same ampacity?
Question 42
When calculating conductor ampacity, what is the derating factor for a conduit containing 4 to 6 current-carrying conductors?
Question 43
Which temperature rating is used for the ampacity of NM (Romex) cable?
Question 44
A branch circuit has 4 current-carrying conductors. What percentage must the ampacity be adjusted (derated) to, according to standard NEC tables?