NEC Code References
Where can the standard ampere ratings of fuses and fixed-trip circuit breakers be found in the NEC?
Table 240.6(A)
What is a short circuit?
An unintended connection between conductors of different potential, creating a low-resistance path for current to flow.
OCPDs of 800 A or less which do not correspond to a standard-size device are rounded up or down?
Rounded up.
What are the three types of conductors that were discussed?
Can overcurrent protective devices be located over the steps of a stairway? If so why? If not, why not?
No, they cannot.
Safety purpose: Protects personnel who may need to operate, inspect, or maintain overcurrent devices from hazards associated with working over stairway steps.
NEC 240.24(F) specifies that they cannot.
Which NEC table provides allowable conductor ampacities?
Table 310.16
What is a ground fault?
Ground Fault – an unintentional connection between an ungrounded conductor and any grounded raceway, box, enclosure, fitting
OCPDs over 800 A which do not correspond to a standard-size device are rounded up or down?
Rounded down
THW conductors are permitted to be installed in wet locations.
True
If a circuit is open, is the switch on or off?
If a circuit is closed, is the switch on or off?
OFF, ON
Which NEC table provides adjustment factors when more than three current-carrying conductors are installed together?
310.15 (C) (1)
Are OCPDs permitted to be installed in bathrooms?
240.24 (E) Exception – OCPDs in Bathrooms: Adds an exception permitting OCPDs to be installed in existing panelboards located in bathrooms.
What are the most commonly used type of circuit breaker in the electrical industry?
Inverse-Time Circuit Breakers
What is ampacity?
The current that a conductor can carry continuously under the conditions of use.
What is any current in excess of that for which the conductor or equipment is rated?
Overcurrent
What does NEC 110.5 require?
Conductors used to carry current shall be copper, aluminum, or copper-clad aluminum, unless otherwise specified by the NEC.
Insulated conductors installed in wet locations shall have a __________ metal sheath or other covering suitable for the location.
moisture-impervious
What is an interrupting rating?
the highest current at rated voltage that an overcurrent protective device is intended to interrupt under standard test conditions.
Overcurrent protective devices are permitted to be installed in clothes closets if they are located at least 12" from combustible materials.
False- OCPDs are not permitted to be installed in locations where easily ignitable materials are stored.
What is the phase color code for 120/208 systems?
Black, Red, Blue, White
310.5(A) was revised to permit the minimum conductor size AWG copper to what size?
16 AWG Copper
What is the phase color code for 120/208 systems?
Brown, Orange, Yellow, Gray
What should overcurrent devices be capable of?
Shall be capable of protecting the electrical components against overloads, short circuits, and ground faults.
There are four exceptions to NEC 240.24(A)(1)-(4). Please describe one.
1. Busways: Overcurrent protective devices (OCPDs) permitted in locations that are not readily accessible, as specified in 368.17(C).
2. Supplementary OCPDs: Permitted to be installed in locations that are not readily accessible.
3. Specific installations: OCPDs permitted in locations that are not readily accessible, as described in 225.40 and 230.92.
4. Portable means: OCPDs permitted in locations that are not readily accessible but can be accessed by portable means.
Parallel conductors have very particular installation rules according the NEC. What are four rules for parallel conductor installation?
same length, same conductor material, same size, same insulation size, same termination