Journeyman Electrician Practice Test-21
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Free journeyman electrician test – 21
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Question 1 of 10
1. Question1 points
The resistance of the very large wire is 220 ohms, at 230 volts ac power supply. What is its resistance when a same value of DC power supply is supplied to it?Correct
The resistance of larger wire is high if it is supplied with DC power supply compared to AC power supply.
Question 2 of 10
2. Question1 points
The maximum load on a feeder or branch circuit must not exceed …………………… of normal rating of the feeder or branch circuit.Correct
Question 3 of 10
3. Question1 points
No. 12 Type T or TW wire in conduit has an ampacity of 20; if you install it in a 50 0 C ambient, what is its new ampacity?Correct
If the wire is installed higher temperature than its rated then its ampacity will derate.
20 * 58% = 11.6 amperes
Question 4 of 10
4. Question1 points
Two smaller wires need not have same cross sectional area to be connected in parallel to form a large wire.Correct
Question 5 of 10
5. Question1 points
For equipment supplied by two ungrounded wires, ………………….. switches may be used to disconnect the circuit.Correct
Question 6 of 10
6. Question1 points
The voltage between conductors on branch circuits supplying screw-shell lamp-holders, receptacles of dwelling units may not exceed…………. volts, except for permanently connected appliances.Correct
Question 7 of 10
7. Question1 points
The demand factor in calculating ampacity should never applied to branch circuits.Correct
Question 8 of 10
8. Question1 points
The current in electrical circuit takes the least resistance path.Correct
Question 9 of 10
9. Question1 points
An AC system of less than 50 Volts must be grounded which of the following conditions?Correct
Refer : NEC 250.20 (A)
Question 10 of 10
10. Question1 points
The total current flows through the 3-wire single phase electrical system is ……………………………Correct
Journeyman electrician Test :
If two circuit paths with low resistance and high resistance are there, Then current flow will choose the path which has low resistance.
The ampacity of the conductor that supply a single motor which is used continuous duty applications shall be 125% of the FLC of the motor. 430.6(A)(1)
So for calculating the conductor size we must multiply full load current by 1.25 and NEC Table 310.16 should be checked for correct wire.