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The NEC test question “A garbage disposal is allowed to be cord and plug connected as long as the cord is no longer than_________.” Can be found where in the code?
A. Artcile 210 branch circuits and dwelling receptacle requirements
B. Article 400 Flexible cords and cables
C. Article 422 Appliances
D. All of the above
- A. Artcile 210 branch circuits and dwelling receptacle requirements
- B. Article 400 Flexible cords and cables
- C. Article 422 Appliances
- D. All of the above
- 422.16(b)3 receptacles shall not be less than 18” or more than 36” and a grounded type plug is not required if it is double insulated.
In what section of the NEC is a 32 volt transformer covered?
AC systems of less than 50 volts shall be grounded under any of what 3 conditions? 250.20A
- 1. if the supply transformer exceeds 150V to ground
- 2. if the supply transformer is ungrounded
- 3. where outside and overhead
Where would you find information in the NEC on “show windows”?
article 210.62 (branch circuits)
What does it say for amperage and linear footage and distance from the top of A show window?
one single phase 15 or 20A receptacle within 18 in of the top of the window and for each 12 linear ft. 210.62
Is a show window receptacle required for a 24v outlet?
What luminaries are permitted to be externally wired?
Chain-supported luminaries used in a show window. 410.14
Using NEC 700.10 as an example, what is the difference between marked and identified when using the following cited code as opposed to the definition of identified? “emergency circuits shall be permanently marked so they will be readily identified as a component of an emergency system”
marked by color to identify a given system; whereas, identified per article 100 definitions means identified is “recognized as suitable for the specific purpose, function, use, environment, application, and so forth. Note: Marked is not defined in the NEC.
Per 700.10B "To ensure that a fault on the normal wiring circuits won’t affect the performance of emergency wiring or equipment, keep all wiring to emergency loads independent of all other wiring. These exceptions apply to:”? -ECMweb.com
- 1. transfer equipment enclosures.
- 2. in emergency or exit luminaries
- 3. load control relay
- 4. j-box attached to emergency system and in unit equipment.
- Courtesy ECMweb.com
What must be remembered about transfer switches and emergency systems versus other loads?
- The alternate power source is permitted to supply other loads in addition to emergency loads; however, the transfer switch for emergency loads can only supply emergency loads.
- courtesy ECMweb.com
504.80 states that instrinsically safe conduit bust be labeled what color and every how many feet?
blue and every 25 ft.
Where can you find grouping of disconnects? And how many disconnects can be grouped together?
230.72. If you said article 230 that would be close enough. And the maximum is 2 to 6 disconnects which are switches or SETS of circuit breakers.
According to 250.53(A)3 a supplemental ground rod must be separated from the other by how far? Be driven how deep into the soil? And this implies how many ohms or less are required for lightning protection? Last, what is the length required for a lighting ground rod per NFPA 780?
- -6 feet separation at least 8 feet buried
- -at 25 ohms or more, unless attached to a water pipe, then an additional ground rod is required anyhow.
- -This means 50 ohms or less are required to ground for lightning protection.
- -10 feet for a lightning protection ground rod.
250.53(a)3 under supplemental ground rods, informational note: What is increased by spacing the ground rods at twice the length of the rod (versus 6ft per code)?
For a feeder or branch circuit disconnecting means (Art 225.39 outside branch circuits and feeders) the rating shall in no case be less than what for One circuit installations, 2 circuit installations, one family dwelling, and all others?
- one circuit- 15A
- 2 circuit- 30A
- one family- 100A
- all other- 60A
Conduit fill percentage for table 4 chapter 9 is what, for 1 wire, 2 wires, or 3 wires or more? Why is the 2 wire out of ratio with the others?
- 53% one
- 31% two
- 40% three
- The two wire would be a single phase load and does not carry the imbalance between two loads and therefore must be counted as a current carrying conductor per 310.15 meaning more heat in the conduit. Remember: the heat into the panel affecting the circuit OCPD is why we derate.
250.64(c) If you are putting number 6 grounding conductor on a cable tray and bonding to a bonding plate, this becomes what? And what does this mean?
It becomes part of the grounding electrode conductor and must be irreversibly crimped. Remember a grounding electrode per Art. 100 is “A conductor used to connect the system grounded conductor or the equipment to a grounding electrode or to a point on the grounding electrode system.”
Where would you find in the NEC the largest grounding electrode size to a rod, pipe, or plate?
250.66 largest is 6AWG copper or 4AWG aluminum.
Where would you find in the NEC isolated grounding receptacles?
Art. 406.3(d) C.A.P.S. “receptacles, cord connectors, and attachment plugs.”
What should copper never come into contact with due to electrolysis?
Aluminum. The metal would deteriorate over time trying to find a balance between valance electrons. According to 110.14
A neutral conductor, one that carries ONLY unbalanced current, versus a grounded conductor which does not, shall be derated? Y/N
No. 310.15(b). However Lighting neutrals would be counted.
Under article 500, what type of material does not apply to gas, dust, or ignitable filings?
pyrophoric: liable to ignite spontaneously on exposure to air. such as phosphorous
What size must conduit be for use as an equipment grounding conductor?
250.52 3/4 trade size or larger.
Single motor taps: no conductor to the motor shall have an ampacity less than (ratio) ________ that of the branch circuit conductors, and to the overload be no more than 25 ft long. Conductor shall be enclosed. For GFPE to a manual motor controller: ampacity of the tap conductor shall be no less than (ratio)_____ GFPE protection, not more than 10ft long, and have an ampacity not less than the branch circuit conductors.
- 1/3rd to overload device.
- 1/10th GFPE and branch OCPD to manual controller.
What is the nipple conduit length under which derate will not be applied, and what is the conduit fill percentage? Where can you find this?
- 24 inches or less there is no derate 310.15(b)3
- Chapter 9 Note 4: Maximum fill is 60%
Any “box” with any dimension over 6 feet will require what of the conductors in the box?
They must be cabled or racked per 314.28(b)
Burial depth for cables is found where? 0-1000v and 1000 volts and more?
300.5 is less than and 300.50 is more than.
Underground direct-buried cables that are not encased or protected t?y concrete and are buried (30 in.) more below grade shall have their location.
identified by a warning ribbon that is placed in the trench at least 300 mm (12 in.) above the cables.
Where is it stated that a conduit run must be complete before installation of conductors? NEC.
300.18 Raceway Installations (A) Complete Runs. Raceways, other than busway s or exposed raceways having hinged or removable covers, shall be installed complete between outlet, junction, or splicing points prior to the installation of conductors.
What size conductor is allowed to be installed in parallel?
310.1 O (H) Conductors in Parallel. General. Aluminum, copper-clad aluminum, or copper conductors, for each phase, polarity, neutral, or grounded circuit: shall be permitted to be connected in parallel (electrically Joined at both ends) only in sizes 1/0 AWG and larger where installed accordance with 310.10(H)(2) through (H)(6)
impedance of a circuit in an aluminum raceway or alluminum-sheathed cable differs from the impedance of the circuit in a steel raceway or steel-sheathed cable; therefore?
Separate raceways and cables must have the same physical characteristics.
When conductors are ran in parallel and an equipment ground is ran in each conduit, the equipment ground size is?
sized up because it is based on overcurrent device size from table 250-122.
400.10 pull at Joints and Terminals flexible cords and cables shall be connected to devices and to fittings so that tension is not transmitted to joints or terminals. informational Note: Some methods of preventing pull on a cord being transmitted to joints or terminals include?
knotting the cord, winding with tape, and using support or strain-relief fittings.
Where would you find feeder demand factors for elevators?
At least 150 mm (6 in.) of free conductor, measured from the point in the box where it emerges from its raceway or cable sheath, shall be left at each outlet, junction, and switch point for splices or the connection of luminaires or devices. Where the opening to an outlet, junction, or switch point is less than 200 mm (8 in.) in any dimension, each conductor shall be long enough to extend at least 75 mm ______ outside the opening. This is found where?
(3 in.) 300.14 Length of Free Conductors at Outlets, junctions, and Switch points
400.4 Notes-Cords that comply with the requirements for outdoor cords and are so listed shall be permitted to be designated as weather and water resistant with the suffix ‘W” after the Code type designation. Cords with the “W” suffix are suitable for use in?
wet locations and are light resistant.
400.4 Notes: Cord types _______shall be permitted in lengths not exceeding 2.5m (08 ft) where attached directly, or by means of a special type of plug, to a portable appliance rated at _____ or less and of such nature that extreme flexibility of the cord is essential.
Regarding a service entrance conductors versus a feeder, passing through a 2nd building to supply a third, can a feeder or a service supply a 3rd building?
- A service cannot involve a 3rd building whereas a feeder can, but requires a disconnect, unless it is outside the third building, under at least 2 inches of concrete for instance.
- 230.3 One Building or Other Structure to Be Supplied Through Another: Service conductors supplying a building or other structure hall not pass through the interior of another building or other structure.
- 225.31 Disconnecting Means: shall be provided for disconnecting all ungrounded conductors that supply or pass through the building or structure.
The term “supply conductors” is defined or not in the NEC. And if it is, where would it be defined? What is a supply conductor?
- It is not defined under article 100 but is in the article 250.102 under bonding conductors and equipment…
- Informational Note: The term supply conductors includes ungrounded conductors that do not have over current protection their supply side and terminate at service equipment or the first disconnecting means of a separately derived system.
Regarding conductors run in parallel, can they be in conduits made of different material?
- No… according to 310.10(H)3
- Where run in separate cables or raceways, the cables or raceways with conductors tall have the same number of conductors and shall have the same electrical characteristics.