Chapter 19 EO test
According to NEC 230.7, conductors other than service-entrance conductors are not permitted in the same raceway as the service-entrance conductors. However, what does Exception No. 2 permit?
Exception No. 2 permits load management control conductors that have overcurrent protection to be installed in the service raceway.
What hot water heater setting is recommended by the Consumer Product Safety Commission to prevent scalding and what additional steps can be taken to avoid injury?
The Consumer Product Safety Commission recommends that the setting should not be higher than 120 degrees Fahrenheit (49 degrees Celsius). To reduce the possibility of scalding, water heaters can be equipped with a thermostatic nonscald mixing valve or pressure-balancing valve that holds a selected water temperature to within one degree regardless of incoming water pressure changes.
Explain why heating elements in water heaters are frequently rated 250 volts for operation on 240-volt circuits.
To help reduce the premature burnout of heating elements, some manufacturers will supply 250-volt heating elements, yet will mark the nameplate 240 volts, with its corresponding wattage at 240 volts. This allows a safety factor if slightly higher than normal voltages are experienced.
Should it be required to run a pump's circuit underground for any distance, it is necessary to install Type UF or Type USE cable or ____, and then make up the necessary splices in a listed weatherproof junction box.
a raceway with suitable conductors
When a non-motor-operated electrical appliance lacks an overcurrent protective device rating, NEC 422.11(E) states that the branch circuit overcurrent protection shall be ____.
both a and c
Water pressure tanks ____ air to maintain delivery pressure in a usable range without cycling the pump at too fast a rate.
compress air
The overload protection for a motor might be thermal overloads (sometimes called ____________________) in the controller, electronic sensing overload devices, built-in thermal protection, or time-delay fuses.
heaters
If the values of fuses or breakers as determined by Table 430.52 do not correspond to standard sizes, ratings, or settings as listed in NEC 240.6, the next ____ rating is permitted.
higher
A disconnect need not be in sight of motor and driven machinery if the disconnect can be individually ____________________ in the open "OFF" position.
locked
NEC 430.103 requires that a disconnecting means for a motor shall ____.
open all ungrounded conductors
In most residential electric water heaters, the high-temperature cutoff and ____ are combined into one device.
upper thermostat
In resistive circuits, current is directly proportional to ____________________ and can be simply calculated using a ratio and proportion formula
voltage
Because a water heater represents a continuous load, the branch circuit must be rated not less than ____ percent of the water heater nameplate rating.
100
UL requires that the power (wattage) input must not exceed ____ percent of the water heater's nameplate rating.
105
Dual-voltage-rated pump motors are rated ____.
115/230
Most installations require motor overload protection not to exceed ____________________ percent of the motor's full-load current rating.
125
If a 115/230-volt, dual-voltage motor has a full-load current of 8 amperes at 230 volts, the same motor connected for 115-volt operation will draw ____________________ amperes.
16
Water pumps that contain all required starting and protection components and connect directly to the pressure switch with no above-ground controller, are often called ____________________ pumps.
2-wire
The Code requirements for standard resistance-type electric water heaters are found in Article 422. Because heat pump water heaters contain a hermetic refrigerant motor compressor, their Code requirements are found in Article ____________________.
440
An individual motor disconnect must be in sight of the motor controller and must disconnect the controller. The NEC definition of in sight means that the controller must be visible and not more than ____ from the disconnect.
50 ft (15 m)
With respect to electric water heater load, explain what off-peak metering means.
Off-peak metering, also known as "time of use" or "time of day" metering, allows the utility to use a separate watt-hour meter/time clock to control the circuit to the water heater. The utility sets the time clock to shut the power off during certain peak periods of the day. In exchange for lower electric rates, the homeowner runs the risk of being without hot water during these off periods and would have to wait for the power to the water heater to come one again.