Which set of references is allowed into the New Mexico CID EL-1 open-book examination?
General Knowledge And Electrical Installation
Question · Easy
Under NMAC 14.10.4, equipment used on circuits over 600 volts that has exposed parts must be marked with which wording?
Where a service mast supports service-drop conductors in New Mexico, NMAC 14.10.4 requires the mast to be at least:
Question · Medium
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For a customer-owned underground service lateral in New Mexico, NMAC 14.10.4 limits voltage drop on those conductors to a maximum of:
A 480Y/277 V switchboard has exposed live parts on one side of the working space and a grounded metal wall on the other (Condition 2). What is the minimum depth of working space required by NEC 2020 Table 110.26(A)(1)?
NMAC 14.10.4 limits aluminum current-carrying conductors to which minimum size and alloy series?
NEC 2020 230.24(B)(4) requires a service-drop conductor to have what minimum vertical clearance above a public street subject to truck traffic?
Question · Hard
If the serving utility does not specify otherwise, NMAC 14.10.4 requires an overhead service support to be at least a 6 inch by 6 inch pressure-treated timber or equivalent round pole with a 6 inch crown, set not less than:
NMAC 14.10.4 prohibits Schedule 40 PVC conduit where the raceway is exposed and less than how far above finished floor or grade?
NMAC 14.10.4 requires outdoor lighting to comply with which New Mexico statute?
Unless the equipment is listed and identified otherwise, NEC 2020 110.14(C) requires conductors terminated on equipment rated over 100 amperes to be selected from which ampacity column?
Under NMAC 14.10.4, a service disconnect located outside a building, with metering on the building, must be in a readily accessible location within how far of the metering equipment?
The primary function of a typical utility distribution substation is to:
Electrical Supply Substations
NEC 2020 110.31 requires a fence enclosing outdoor electrical equipment over 1000 volts to be at least:
NEC 2020 Table 110.31 requires what minimum distance from a substation fence to live parts rated 12.47 kV (nominal voltage 1001–13,799 V)?
Compared with a single-bus distribution substation, a breaker-and-a-half scheme is selected primarily because it:
Station-class surge arresters at a distribution substation are installed to:
A substation ground grid of buried bare conductors and ground rods is designed primarily to:
A 25 kVA single-phase pole-mount transformer is fully loaded on a 240 V secondary. What is the approximate full-load secondary current?
Transformers
What is the defining feature of a completely self-protected (CSP) overhead distribution transformer?
A 75 kVA three-phase transformer is rated 480 V on the secondary. What is the approximate full-load secondary line current?
A single-phase distribution transformer is rated 7200 V primary and 240 V secondary. What is the turns ratio of the primary to the secondary?
A 75 kVA single-phase transformer rated 240 V secondary has a nameplate impedance of 2 percent. What is the approximate available secondary bolted-fault current, ignoring source impedance?
Two identical single-phase transformers are connected open-delta to serve a three-phase load. The bank's usable three-phase capacity is approximately what fraction of a closed-delta bank made of three of the same units?
The kVA rating on a distribution transformer nameplate is a rating of:
On an additive-polarity single-phase distribution transformer, connecting one primary bushing to the adjacent secondary bushing and applying a reduced primary voltage causes the voltage measured between the remaining primary and secondary bushings to be:
A 500 kVA three-phase transformer is rated 12,470 V on the primary. Using NEC Table 450.3(A) for an unsupervised location, the maximum primary circuit-breaker setting is 300 percent of rated primary current. What is the next standard breaker size permitted by Note 1 if the calculated maximum is not a standard rating?
For a transformer over 1000 volts in a supervised location, NEC 2020 Table 450.3(A) limits the primary fuse to a maximum of what percentage of rated primary current?
A closed-delta bank of three 25 kVA single-phase transformers is converted to open-delta by removing one unit. What is the approximate usable three-phase capacity of the remaining bank?
Compared with a pole-mount distribution transformer, a pad-mount transformer is typically selected when:
ACSR overhead line conductor is constructed as:
Conductors
Using NEC 2020 Table 310.16, what is the 75 degree C ampacity of 4/0 AWG copper with not more than three current-carrying conductors in a raceway, 30 degree C ambient?
Using NEC 2020 Table 310.16, what is the 75 degree C ampacity of 4/0 AWG aluminum with not more than three current-carrying conductors in a raceway, 30 degree C ambient?
A level span of overhead conductor weighs 0.50 lb per foot, is 400 feet long, and is pulled to a horizontal tension of 2,500 lb. Using the parabolic sag formula s = wL² / (8T), what is the midspan sag?
A 480 V three-phase feeder uses 4/0 AWG aluminum (211,600 circular mils). The load is 200 A and the one-way length is 200 feet. Using VD = 1.732 × K × I × D / CM with K = 21.2 for aluminum, what is the approximate line-to-line voltage drop?
Compared with ACSR of the same aluminum cross-section, AAC (all-aluminum conductor) is typically chosen when the line needs:
Six current-carrying 4/0 AWG copper THWN conductors are installed in one raceway in a 30 degree C ambient. Starting from the Table 310.16 75 degree C ampacity of 230 A, what is the adjusted ampacity after the NEC 2020 Table 310.15(C)(1) adjustment?
An overhead ACSR span is sagged in cool weather to the initial (unloaded) stringing sag. After years of load, wind, and ice, the clearance to a roadway is checked at maximum operating temperature. The sag that must be used for that NESC clearance check is:
On an overhead distribution feeder, increasing conductor size from 1/0 AWG ACSR to 4/0 AWG ACSR, with the same span and similar tension as a percent of rated strength, will generally:
The circular-mil area used in voltage-drop calculations for 4/0 AWG is:
Under NESC 2007 Rule 250B, most of New Mexico lies in the Light loading district. The Light-district combined ice-and-wind case is:
NEC 2020 310.10(G) permits paralleled conductors 1/0 AWG and larger only when they are the same:
Using the common setting-depth rule of 10 percent of pole length plus 2 feet, a 40-foot wood distribution pole in firm soil should be set approximately:
Poles And Structures
In the ANSI wood-pole class system, which statement is correct?
Under NESC 2007 Table 242-1, an overhead supply crossing of a railroad track that requires a crossing permit is generally built to which grade of construction?
A down guy is installed on a 40-foot pole with the attachment 32 feet above the anchor. For a lead-to-height ratio of 1 to 1, the anchor should be placed approximately how far from the pole?
A wood crossarm on a 12.47 kV line must keep phase conductors far enough apart to satisfy NESC 2007 Rule 235 at the support and in midspan. The clearance that usually controls pin spacing on the arm is:
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