1a. If power is measured by voltage and current, total voltage is relatively constant, and total current changes depending on how many loads you have on the circuit (in parallel), then how can power output be constant?

2. On a circuit that spreads the loads evenly between the different phases, is there any current on the neutral?

2a. (2 rephrased):If I want to minimize current on the neutral, should my aim be to ensure the current on each phase is as equal as possible, by ensuring the resistance (load) on each phase is as equal as possible?

3. If an appliance is "x watts" (Like a 30 watt bulb), does that mean it will fail if more power than 30 watts is run through it? Does that mean it was designed to run at 30 watts only? Does it mean that "if you put 120 volts (for example) through this resistor, it will experience a current flow resulting in 30 watts of power? Where do wattage ratings come from, and why do they exist?

3a. If I increase the voltage to an appliance (Like going from 120v to 240v), what will happen? Overload, fail to operate, operate faster/brighter/etc?

3b. If an appliance is listed at "30 watts", is this just an indirect way of measuring its resistance? Why aren't lightbulbs "480 ohm bulbs"? Why is the standard to measure in terms of power? ]]>

http://technet.microsoft.com/en-us/s.../bb897434.aspx ]]>

i have been told that you don't need schooling from some, and have been told you do need the schooling not Shure with is correct?

I also have been told that in order to prove how many hours you have been in the field that your boss has to fill out paper work stating hours worked etc.

what happenes if you left a company on bad terms is the employer mandated to fill out paperwork? If not can you use pAystubs as proof of hours down ? ]]>

QUESTION:

A person buys a house without a garage, and later decides to have a 2-car detached garage built. The owner’s electrical needs are as follows: Garage is to be powered with a 120/240V subpanel installed in the garage, using a 40-amp underground feeder from the main panel in the basement of the house. The owner also wants to be able to control the outdoor garage lights from inside of the garage as well as inside the house. The lighting circuit is to be rated at 15 amps with no other non-lighting outlets connected to it. Receptacle outlets are to be fed by two 20-amp circuits.

1. What is the minimum allowable size for each of the ungrounded (hot), grounded (neutral), and equipment grounding (green) conductors if THHN copper conductors are to be used?

2. If the minimum size conductors are used, what is the minimum allowable size PVC conduit that can be used?

3. What is the minimum allowable size metal junction boxes to be used in the basement and garage to contain all conductors in Question 1?

ANSWERS:

1. Based on Table 310.16: #8 THHN has a rating of 55 amps, and since there are 6 current-carrying conductors in the raceway, (Table 310.15 B2a), 55 * 0.8 = 44 amps. So use #8 ungrounded (red/black) and #8 white (neutral). Based on Table 250.122, use #10 green grounding wire. For the 3-way common and traveler wires, use #14 black, red, and blue.

2. Since the maximum fill of conduit is 40% (Chapter 9, Table 1), and the sums of the cross-sectional areas of the conductors are as follows: 3@0.0366, 3@0.0097, 1@0.0211, for a total of 0.16 square inches. The area of a 3/4” conduit is 0.442 square inches. 40% is 0.177. So a ¾” barely meets the requirement. I would personally use 1” to make the wires easier to pull.

3. Each junction box would contain all 7 conductors in Question 1, as well as a #14-3 NM-B cable and a #8-3 NM-B cable. All grounding conductors count as one. The remaining 6 are paired with a conductor from the cables, giving a total of six #8 and 6 #14, and one #10 grounding. For each #14, 2 cubic inches are needed. For each #8, 3 cubic inches. For a #10, 2.5 cubic inches. Total cubic inches needed is 17.5. Therefore, a 4” square by 1.25” deep barely passes with 18 cubic inches. I would personally use a 4-11/16” square X 1.25” because it would provide more freedom, and a 4” box is not likely to have 1” knockout openings, where a 4-11/16” would. ]]>

INSULATED

SOLID

STRANDED

BARE

i chose insulated, WRONG, i assume it is stranded ???? i looked at 250.62 and it has all listed,please help me on this 1,it does not say if its a grounding electrode,equip grd ,or Iassume raceway must be a conduit, Ihave seen thwem all in raceways,cable tray,etc....

Let me know your thoughts please..thanks ]]>

switch with terminals rated for 75 degrees c. Where did they get the number 65 amps for this question? ]]>

73. The ac ohms-to-neutral impedance per 1,000 ft of 4/0 AWG aluminum condctor in steel raceway is ____.

(a) 0.06 ohms

(b) 0.10 ohms

(c) 0.22 ohms

(d) 0.11 ohms

I say the answer is (b) 0.10 ohms based on Chapter 9, Table 9. I am referencing the steel conduit column under Alternating current resistance for aluminum wires and the 4/0 AWG size row. The second number in the the column is that for ohms ber 1000 feet which is 0.10. The Answer Key says the correct answer is (c) 0.22 ohms and that the answer is found in Chapter 9, Table 9.

I am trying to figure out where I went wrong with this question.

Thanks! ]]>