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Disconnects & Sizes
Multi-Motor Feeders
HVAC: Article 440
Special Motors & Drives
PF, Shunting & Control
200
Equipment is 'in sight from' another if it is visible and not more than how many feet away?
50 ft (15 m)
200
Which section sizes feeder conductors for several motors, or a motor plus other loads?
430.24
200
What does RLC stand for on an air-conditioning nameplate?
Rated-Load Current
200
Which duty type is 'operation at a substantially constant load for a short and definitely specified time'?
Short-time duty (defined in Article 100; duty types are used in 430.22(E))
200
A power-factor correction capacitor is connected in series or in parallel with the motor?
Parallel *
400
The branch-circuit OCPD may serve as the disconnect only for stationary motors up to what horsepower?
1/8 hp
400
Which sections cover short-circuit and ground-fault protection for: a multi-load branch circuit, a motors-only feeder, and a feeder with motor AND nonmotor loads? Give all 3 section numbers.
430.53; 430.62; 430.63
400
Which Part of Article 440 covers branch-circuit conductors for an air conditioner?
Part IV *
400
Wye-start, delta-run motor: conductors on the load side of the controller need what % of the motor FLC?
72% (58% x 125%) per 430.22(C)
400
After a power-factor capacitor is added, what happens to the current on the line side and on the load side of the capacitor?
Line side decreases; load side stays the same
600
A motor-circuit switch must have a current rating of at least what % of the motor FLC (430.110(A))?
115%
600
Under 430.62(A), the largest branch-circuit device rating plus the sum of the other motor FLCs gives the minimum or the maximum feeder device size?
Maximum *
600
This value replaces RLC when the overload device allows more than 140% of RLC.
Branch-Circuit Selection Current (BCSC)
600
For a wound-rotor motor, what is the maximum Table 430.52 multiplier for nontime-delay and dual-element fuses, and for an instantaneous-trip breaker?
150% for the fuses; 800% for the instantaneous-trip breaker (Table 430.52(C)(1)) *
600
Which table limits overcurrent protection for motor control circuit conductors?
Table 430.72(B)
800
Which is NOT a standard disconnect size: 60 A, 100 A, 125 A or 200 A?
125 A
800
Name the three conditions that let several motors share one disconnect (430.112 exception).
Parts of one machine; one set of branch-circuit protection; all in one room within sight of the disconnect
800
What is the maximum short-circuit/ground-fault device for a single motor-compressor, and the maximum if that will not carry the starting current?
175% of RLC or BCSC; up to 225% (440.22(A))
800
A synchronous motor is used at a leading power factor. By what do you multiply the table FLC for 90% PF and for 80% PF motors?
1.1 for 90% PF; 1.25 for 80% PF (Table 430.250 power-factor adjustment) *
800
Under 430.35, are automatically started motors generally allowed to have their overloads shunted during starting?
No, not generally (430.35(B)). Shunting is allowed only if ALL four conditions are met: (1) the starting period exceeds the time delay of available overload devices; (2) a listed means senses motor rotation and prevents shunting if the motor fails to start; (3) the shunting time is limited to less than the motor's locked-rotor time rating; (4) the motor shuts down and needs a manual restart if running condition is not reached
1000
For stationary AC motors rated over what horsepower may the disconnect be a general-use or isolating switch marked 'Do not operate under load'?
100 hp (over 100 hp AC; over 40 hp DC) *
1000
Name the four load categories and their multipliers added up in 430.24.
125% highest-rated motor; 100% other motors; 100% noncontinuous load; 125% continuous load
1000
Maximum overload settings for a motor-compressor: separate overload relay, thermal protector, and fuse or inverse-time breaker? All of these are covered by the same code article. Name the article too.
140%; 156%; 125% of RLC (or BCSC). All are in Article 440 (section 440.52)
1000
A wound-rotor motor on heavy starting duty has the secondary resistor separate from the controller. What % of the secondary FLC is needed for the conductors between them?
45% (430.23(C), Table 430.23(C)) *
1000
Control conductors stay inside the enclosure vs. leave it: which Column of Table 430.72(B) applies to each, and what % of which ampacity table?
Stay in: Column B, 400% of Table 310.17; leave: Column C, 300% of Table 310.16 (60°C column)