# So You Call Yourself A ME part 3 (More Easy)



## ship (Dec 26, 2005)

131) On a three phase delta panel, distribute evenly a load of (4) S-4 575 watt Lekos, (2) Mac 600s, (6) Par 36 pin spots with 30watt lamps, and (6) Technobeams. Now distribute this load on a three phase Wye panel.
132) What is the minimum size of feeder cable for the above services?3
75) What is the exact amperage of a 575 watt instrument at 115, 118 & 120v?
106) A 1/4" x 1" copper bar would have how many circular mills in diameter? (Cir mills x π/4)106) A 1/4" x 1" copper bar would have how many circular mills in diameter? (Cir mills x π/4)
97) A HPL 575 at 115 volts draws 5 amps, how many amps does it draw at 122 volts?
94) A 10 amp load on an extension cord with ½ ohm resistance causes a 5 volt drop, how many volts drop would a 30 amp load cause?
40) On a three wire single phase system, the first leg carries 60 amps, the second carries 50, how many amps does the neutral conductor carry?
41) A step down transformer with a 5:1 ratio fed with 120vac has how many volts potential? 
42) A transformer works by creating a magnetic field around the coil, if the primary winding has 100 turns on a 4:1 step-down transformer at 120 volts, how many volts and turns does the secondary winding have?
85) An electric iron draws 5.3/4 amperes when connected to 115 volts. What is its resistance in ohms?
86) Suppose a bad connection in the iron’s plug or iron added 9 ohms resistance to the iron above, what current would the iron draw on 115 volts?
88) If a 19 ohm iron has one ohm resistance at 115 volts, and 5.75 amperes flow, how many amperes would flow with 10 ohms resistance at the same voltage?
89) The above voltage was measured at the plug, what would be the voltage at the iron? E=IxR
20) A pinspot/mirror ball fixture/ PAR 36 Sealed Beam Lamp, has a transformer and lamp voltage of 5.5 volts, and a wattage of 30. On a six bar, what is the total voltage, wattage, and amperage of the bar, and each fixture at the plug and the lamp? How many lamps on a 120 volt system without transformers would be needed, and how many fixtures with transformers can be run off of one 20 amp service?


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## krhodus (Dec 27, 2005)

75) What is the exact amperage of a 575 watt instrument at 115, 118 & 120v? 

I am going to take a stab at this and use my very limited electrics knowledge. W=VA, so 575W/115v would be 5 amps, 118v would be 4.87 amps, and 120v would be 4.79.

Kevin


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## TheHeadhunter (Dec 27, 2005)

97) 4.713 amps (approx)


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## robartsd (Jan 16, 2015)

TheHeadhunter said:


> 97) 4.713 amps (approx)


No, as with any purely resitive load, incandescent lamps draw more current with higher voltages and less current with lower voltages. The lamp would draw about 5.3 amps burning brightly at about 646W until it met it's early end of life.


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## AlexDonkle (Jan 18, 2015)

robartsd said:


> No, as with any purely resitive load, incandescent lamps draw more current with higher voltages and less current with lower voltages. The lamp would draw about 5.3 amps burning brightly at about 646W until it met it's early end of life.



This thread is just over 9 years old....


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## David Ashton (May 7, 2016)

The correct answer is unknown as a lamp is a non linear resistance and can only be approximated without more data.


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