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So You Call Yourself A ME part 2

Discussion in 'Question of the Day' started by ship, Dec 26, 2005.

  1. ship

    ship Senior Team Emeritus Premium Member

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    78) Why is solder in old lighting fixtures harder to remove than new solder?
    79) What is Alternating Direct Current?
    121) At what percentage does voltage drop become un-acceptable?
    122) When using a generator, how many ohms resistance can the grounding rod have?
    123) What are the two types of feeder cable authorized for stage use?
    124) According to the NEC 1999, what is the maximum allowable length of SJ cable for stage use?
    125) How many amps is 12ga. THHN wire rated for?
    126) How many amps is 14ga SJ cable rated for?
    127) How many watts is 12ga. SO cable rated for?
    128) What is the difference between a NEMA 5-15 and L5-15 Plug?
    133) What is the difference between SJOW and SJOOW cable?
    135) Why would 12/3 SO cable be rated for more in amperage than 12/19 SO wire?
    136) What is the specified torque on a Camloc set screw?
    142) What is the minimum size wire which should be attached to an NEMA L21-30 plug?
    145) What is “Poor Mans 220?”
    146) Why shouldn’t Gaffers tape be used over electrical connections on stage? (2 reasons)
    150) Why aren’t twofers without molded junctions approved of by the NEC?
    151) What is the proper name for Greenfield or BX cable?
    152) What does the NEC say about attaching a 25' or longer Edison cable directly to a service panel - why?
    156) 2/0 SC Cable is rated for how many Amps?
    163) Which lamp base is bigger: candelabra, Intermediate, or mini candelabra?
    177) What does cmils have to do with wire?.
    178) What two colors are the neutral wire allowed to be according to the NEC?
    179) On European cable wired for 120v. what color is the neutral supposed to be?
    180) On Zip Cord or SPT-2, what determines which wire is the neutral?
    184) The grey wire on an electronic component is what?
    185) 18' is the minimum NEC height of a service drop over a sidewalk, private driveway, or street?
    186) What happens inside a standard circuit breaker when it trips?
    187) How do you tie a UL knot?
    194) In a 1900 type box, If the frame of a standard receptacle/outlet is grounded, why does the NEC say you should still run a ground wire to the conduit box?
    197) Why won’t a GFCI protect against shorts, or overloads?
    198) When the neutral conductor touches a grounded surface such as a metal outlet box on the load side of a GFCI, the GFCI will do what?
    199) What two applications can you not use a GFCI receptacle for?
    200) What is the difference between a 3-way and 4-way switch?
    201) What does the break-off tab on a receptacle do?
    203) On a switched circuit feeding through the lampholder, there are three wires, the Black, White and Red, which two wires would be correct to use to feed the lampholder?
    205) The wires connected to the “A” and “B” terminals on a 3-way switch are called what? What color are they?
    209) Are you allowed to ground to sewer pipes? Why? What about water inlet pipes and regulations for them?
    216) Name three ways you can reduce grounding rod resistance in the soil.
    217) What is the difference between grounded, bonded and grounding conductors?
    219) What is the difference between time delay and dual element fuses?
    221) How do you “Float the Ground?”
    222) Do you count the neutral wire when determining the capacity of multi-cable or raceways?
    225) What is the current recommended practice for which side is up on a receptacle and why?
    226) When mounted horizontally, which side of a receptacle should be mounted up?
    227) Under what conditions can you use a ground-lift adaptor?
    228) What is a DPDT Switch?
    235) Why are household dimmers in a cord fed quad box frowned upon by the code?
    238) How many Edison cube taps can you stack?
    243) Would a GFCI preform properly if fed by a 12/2 SPT-2 (Zip Cord)? Why or why not?
    255) How many volts does analog run off of?
    256) Which pin on a 3-pin XLR plug is the positive?
    259) Rubber such as the jacket of wire has bad chemical resistance to two things, which are they? Acids, Alcohol, Caustic Bases, Gasoline, Grease, Kerosene, Oil, Solvents, or Water?
    260) Which of the following has only fair chemical resistance to grease and water? (The rest have good)
    Nylon, Melamine, Phonolic, Urea, Ployvinyl Chloride, Polycarbonate, or Rubber
    261) Which material has the best continuous temperature rating, Nylon, Urea, Phenolic, or Ployvinyl Chloride?
    262) An electric motor is over-heating and it is not from the load, what is probably the cause?
    263) What problems might a switch or dimmer mounted on the neutral leg of a lamp cause?
    280) If the show lights suddenly dim, and it is not from the power company because it is only your lights, what is this an indication of and what will probably happen next?
    281) What is the minimum amount of twists on a pigtail splice for a good connection?
    283) Acid fluxes are more useful than rosin flux for tinning large wire. True or False? Why?
    288) Of the two Strain Relief Inserts in a Bates plug with a flat and rounded side to each, describe the quantity and position of them when using 14/3 SJ wire, 14/3 SO, 12/3 SJ, 12/3 SO, and 16 ga heat wire in a fiberglass sleeve.
    289) Why would the use of vinyl tubing be frowned upon by the NEC when used on a 16 ga power cord over a SJT jacket, into a plug?
    299) What is the difference between MTW, THHN, and TW wire?
    300) On a Slip Panel mount receptacle mounted vertically, does it matter which end is up, and if so, which end should it be?
    301) On a twist Panel mount, such as a L6-15R, our 208v. connector, does it matter which end is up, and if so which part should it be?
    302) If the Diversitronics strobe is 3,000 watts, why is it permissible to use a L6-15 plug on it?
     
  2. CHScrew

    CHScrew Active Member

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    151) Armored cable
    184) The gray wire is incoming power.
    256) Pin 2
    262) probably because of low line voltage. making the motor draw excessive current causing it to overheat
     
  3. AVGuyAndy

    AVGuyAndy Active Member

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    145 - I beleive it is the "dryer plug"
    197 - Because that's the circuit breaker's job.
    256 - A trick question. :) Depends on the gear. Today's standard is pin 2, but it used to be pin 3
    127 - 15a
     
  4. ship

    ship Senior Team Emeritus Premium Member

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    145) not a correct answer though a dryer plug could be wired by way of this means.
    197) urr... electrons don't follow union rules.
    256) new to me, I follow the backstage handbook.
    127) incorrect answer.
     
  5. ship

    ship Senior Team Emeritus Premium Member

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    What "type" of cable/wire is this?
     
  6. soundman

    soundman Well-Known Member

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    7 Why is solder in old lighting fixtures harder to remove than new solder?

    Anything to do with the lead in the solder?

    145) What is “Poor Mans 220?”

    two 110 drops twoferred together.

    197) Why won’t a GFCI protect against shorts, or overloads?

    As long as the current across the hot and neutral are the same a GFCI is happy, so and overload will not trip it.

    235) Why are household dimmers in a cord fed quad box frowned upon by the code?

    Heat?

    262) An electric motor is over-heating and it is not from the load, what is probably the cause?

    not getting enough power

    180) On Zip Cord or SPT-2, what determines which wire is the neutral?

    One wire should be ribbed and the other is smooth I think the smooth is the neutral.
     
  7. ship

    ship Senior Team Emeritus Premium Member

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    7) Could be, is there a change due to heat or age that goes on in such a connection?

    145) Two drops of 110 together? Can you explain further? Wouldn't such a concept tied together create quite the short? Much less in 110v drops, that does not really answer the question other than if you know the answer.

    197) Ding, Ding, Ding.
    235) Wrong answer, check a specific NEC rule. Box cubic fill capacity in filling was not a part of the question. Speaking of that, ever read the instructions on a household dimmer about the question of cooling fins clipped off and the de-rating of the dimmer? A 600w household dimmer without all it's cooling fins is rated for how many watts? How many should it need to be located next to a duplex receptacle and half it's wings clipped off? Would bending down instead of breaking off the cooling fin/wing still allow maximum wattage?

    180) Absolutely incorrect and something specified specifically in the NEC.
     
  8. soundman

    soundman Well-Known Member

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    145) Two drops of 110 together? Can you explain further? Wouldn't such a concept tied together create quite the short? Much less in 110v drops, that does not really answer the question other than if you know the answer.

    Well using two 110 outlets that are out of phase from each other you can wire the hot to hot and get 220 and neutral to neutral to get -220.

    The other answers were more like hunches then fact based.
     
  9. ship

    ship Senior Team Emeritus Premium Member

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    So how is this that you can measure 220 btween hot hot an neutral at the same time? Most meters I use only have two probes not three.

    "Poor Mans's 220" is not a reference to 110v (mis-stated in voltage.) This much less in reference to te neutral.

    You are very close in concept, but not really in term or application.

    On the oter answers, they are good answers in general. Too bad that out of how many hundred members, others have not the guts or brass ones you have. One's hunch is often the best source for wiring. Rely upon it for keeping you safe, and in answering one's hunch, you learn different at times and will memorize what was different from unch. Given this, nothing wrong with having the guts to reply upon a hunch as long as it's on-line. This way once it gets to doing it in reality, such a question you will know for sure.
     
  10. inspector_gizmo

    inspector_gizmo Member

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    Its a little late, so I'm going to answer the ones I know off the top of my head.

    123) What are the two types of feeder cable authorized for stage use?
    Type S and Type SJ however SJ is very limited in use, leading us to question number 124.

    124) According to the NEC 1999, what is the maximum allowable length of SJ cable for stage use?
    The maximum allowable length of SJ cable for stage use is 20 feet and it must be protected from traffic.

    128) What is the difference between a NEMA 5-15 and L5-15 Plug?
    NEMA 5-15 is a standard 15 amp edison plug, while a NEMA L5-15 is a locking 15 amp edison plug more commonly known as a twistlock.

    133) What is the difference between SJOW and SJOOW cable?
    I believe that SJOW is a Jr. Hard service cable that is oil and water resistant, while SJOOW is a Jr. Hard service cable that is oil, water, and weather resistant.

    187) How do you tie a UL knot?
    A UL knot is tied by taking about 3 inches of the hot and neutral wires and making a loop with each wire, one going above and one going below then placing the ends of the wire through its opposite loop. Somewhat hard to explain, but i would be happy to provide a picture.

    201) What does the break-off tab on a receptacle do?
    The break-off tab on a receptacle ties the terminals of the upper and lower outlets together, when the tab is broken it allows each of the two outlets to be fed individually i.e. a 15 amp circuit connected to the top part of the receptacle and a different 15 amp circuit connected to the bottom half of the receptacle.

    228) What is a DPDT Switch?
    A DPDT Switch is a Double-Pole Double-Throw switch, a special type of switch used normally to disconnect both the hot and neutral as opposed to just a hot, common to loads such as electric motors or Ship's lamp tester.

    I'm not sure how entirely correct my answers are, but I figured I would throw in my $.02.
     
  11. ship

    ship Senior Team Emeritus Premium Member

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    123) Wrong. I believe the question was "What type of Feeder Cable."
    124) Wrong.
    128) Correct
    133) Wrong
    187) Correct
    201) Correct
    228) Correct though if I'm switching a neutral it is only in rare instances and with high quality switches that guarentuee both lines are switched at the same time. Switching a neutral is frouned upon by the NEC. Lamp testers I build leave their neutral in tact and not switched. Not really a reason to switch the neutral on a lamp tester.
     
  12. Mayhem

    Mayhem Senior Team Emeritus Premium Member

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    DPST switches are commonly found with neon illumination in them (at least here in Australia), so it is fairly common to see both the active and neutral switched.

    Often see some people wire them incorrectly so that the neon is illuminated when the switch is off as well as on.

    12V DC illuminated switches can be found with just 3 terminals on them, as the ground (negative) terminal is only used to activate the illumination.

    Mains DPDT illuminated switches can also be wired this way, so that the illumination is retained but the neutral is not actually switched.

    Enjoying reading the responses to these questions.
     
  13. CHScrew

    CHScrew Active Member

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    Sorry.

    BX was a particular brand of ArmorClad Cable made by General Electric. It has a flexible aluminum or steel sheath over the conductors and is mostly resistant to damage

    [​IMG]
     
  14. ship

    ship Senior Team Emeritus Premium Member

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    So type "AC" armored cable is what?
     
  15. sound_nerd

    sound_nerd Active Member

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    without reading the other replies, here goes.
    78) higher temp solder was used
    145) taking two 120v circuits, and combining them to form a 220v "circuit".
    150) is it a stress relief issue?
    163) candelabra
    201) splits the receptacle into a two circuit, or at least a split feed unit. You need one feed for each the top and bottom of the unit, allowing you to have seperate switches or breakers for each plug.
    228) double pole, double throw. Two lines can be switched between two different "on" positions, and an off.
    262) not enough power getting to the motor.
     
  16. ship

    ship Senior Team Emeritus Premium Member

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    78) Where does one find low verses high temperature solder? Could be a percentage of the makeup of the solder but probably short of asking Altman what grade of solder they were using in the 1970's for their cyc lights later in the 90's requiring a propane torch to melt to solder to, not a correct answer. There is some form of change instead that is going on I think within the solder given time and heat. Though I might be wrong.

    150) while also a problem, this specifically is not referenced as part of the problem. Though in the past I have seen some other than factory modified strain relief fittings even by me doing so in making a strain relief more easier clamp two wires - also against code to modify a plug by the way. In the end - no matter if done or not in the industry, there is a specific reason that it is specifically against code to use the plug or connector as a twofer terminating device.

    163) nope.
    201) For the most part good and correct.
    228) For the most part good and correct.
    262) For the most part in laymens terms correct. Given this how does one correct for this?
     
  17. sound_nerd

    sound_nerd Active Member

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    For the twofer issue, according to code and the design of the plugs, you may not nave more than one wire terminating in each sleeve of the plug? So, if making a twofer and terminating in the plug, you now have two wires in each sleeve, as opposed to the one required by code?

    As a side note, if this is the case, could you not have your twofer split out inside of a duplex box (or other elec. box) mid-cable?
     
  18. ship

    ship Senior Team Emeritus Premium Member

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    Very good though the language I remember is something like "A plug is not an interconnection device."

    Given a 1900 box is not a plug, than it would be permissible were 1900 boxes permissible in most instances to be installed on cord. Given they are not, it's not much of a worry. There are exceptions for the use of a quad box on a cable and it's often done to code or not, but it is not permissible as a twofering device by way of any normal standards or even four outlet standards. (This is a very much abused rule by even IBEW electricians.)

    On the other hand if absolutely necessary and you comply with all other rules on the subject, and otherwise on the market there is no other solutions, than it could very much be. I at one point recently made a fused and conduit clamp mounted quad box into a Edison to like eight staggered cord IEC output device. Given there was nothing else available to mount on a truss and distribute power as needed, and it otherwise kept to professional standards, such equipment on a world tour to a major rock and roll show was not challenged. This given I don't use 1900 boxes for just about anything I wire. Instead Bell Boxes or handy boxes are much more useful.

    None the less, the use of a quad box given there is other solutions for a twofer would also be other than compliant with code. Also, given some old time instances where a plug was the only option, using a 1900 box would be even more against code to use.

    By the way, this within a volconizing splice of the cord is by no means used sufficiently in the industry. One might not believe the number of plug spliced twofers both from other companies or done by techies in the field I cut up per year. Such a thing would also and especially include a 120 to 208v adaptor which is hugely dangerous.
     
  19. Radman

    Radman Well-Known Member

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    With only the 2002 Handbook edition of NEC to guide me:

    78 ) Why is solder in old lighting fixtures harder to remove than new solder?

    older lighting fixtures were manufactured with lead core solder, and lead has a higher melting point than rosin, which is at the core of today's solder


    121) At what percentage does voltage drop become un-acceptable? more than 3% drop at the furthest from the source, 5% elsewhere


    124) According to the NEC 1999, what is the maximum allowable length of SJ cable for stage use?

    Well, according to NEC 2002 it's 1.0 m (3.3 ft)


    125) How many amps is 12ga. THHN wire rated for?

    30


    126) How many amps is 14ga SJ cable rated for?

    15


    127) How many watts is 12ga. SO cable rated for?

    20


    128) What is the difference between a NEMA 5-15 and L5-15 Plug?

    5-15 is standard 15 amp edison, L5-15 is standard 15 amp twistlock, the L designates locking


    133) What is the difference between SJOW and SJOOW cable?

    SJOOW is oil resistant, SJOW isn't


    135) Why would 12/3 SO cable be rated for more in amperage than 12/19 SO wire?

    I'd assume because of the heat produced by so many wires next to eachother. I think a better way to put it is that 12/19 is rated less, rather than 12/3 being rated more


    142) What is the minimum size wire which should be attached to an NEMA L21-30 plug?

    of the thermoset types, 8 awg


    146) Why shouldn’t Gaffers tape be used over electrical connections on stage? (2 reasons)

    I'll give you three: not rated as an electrical insulator, with heat it tends to crisp and fall off, and for the third reason, it's my one of my pet peeves!


    156) 2/0 SC Cable is rated for how many Amps?

    200 (?)


    177) What does cmils have to do with wire?.

    cmil (or circular mils) is the unit of measurement the AWG (American Wire Gauge) is based upon


    178) What two colors are the neutral wire allowed to be according to the NEC?

    white and gray


    180) On Zip Cord or SPT-2, what determines which wire is the neutral?

    the wire without the sharp ridge is supposed to be neutral


    184) The grey wire on an electronic component is what?

    neutral?


    185) 18' is the minimum NEC height of a service drop over a sidewalk, private driveway, or street?

    street


    186) What happens inside a standard circuit breaker when it trips?

    a switch opens the circuit, I forget the specifics


    187) How do you tie a UL knot?

    I used to know that one


    197) Why won’t a GFCI protect against shorts, or overloads?

    gfci only protects against ground faults; shorts and overloads are not ground faults


    200) What is the difference between a 3-way and 4-way switch?

    1 way. 3 way has 3 positions, 4 way has 4 positions, 4-3=1

    oh snap, brain blast! that was wrong, 3 way switch I think can have 3 switches in seperate locations controlling the same circuit, all functioning as if they were the only switch; 4 way works trhe same except replace the 3's with 4's


    203) On a switched circuit feeding through the lampholder, there are three wires, the Black, White and Red, which two wires would be correct to use to feed the lampholder?

    black and white


    more to come, need break
     
  20. Radman

    Radman Well-Known Member

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    201) What does the break-off tab on a receptacle do?

    when not broken off, it connects the two outlets so they are the same circuit. When you break it you can connect each outlet to a different circuit.


    178) What two colors are the neutral wire allowed to be according to the NEC?

    in addition to the colors I already mentioned, any other color may be used provided there are three continuous white stripes along the length of the wire.


    216) Name three ways you can reduce grounding rod resistance in the soil.

    salt, water, additional rods :p


    217) What is the difference between grounded, bonded and grounding conductors?

    grounded conductor is a conductor that is intentionally connected to ground, usually referred to as the "neutral"

    bonded refers to permanently connected metallic parts to act as a grounding conductor that can handle any likely current

    the grounding conductor is the actual wire used to connect to the grounding electrode (ie the green one)

    This reminds me of the last show I did. I was having trouble with some parcans tripping the CB on the dimmer, and it was narrowed down to one isntrument. It was checked to see if there was a wire shorting somewhere inside, but it looked OK. The cable was checked for proper wiring, OK as well. Finally he checked the wiring of the fixture plug, aha! We often joke whenever we have to wire a bunch of plugs "so black is ground, right?" Well apparently whoever wired this fixture thought so! The ground and the hot conductors were swapped in the plug! I laughed at that one for quite a while.


    222) Do you count the neutral wire when determining the capacity of multi-cable or raceways?

    what capacity? could you explain more?


    226) When mounted horizontally, which side of a receptacle should be mounted up?

    slightly confusing question, what kind of receptacle?


    228) What is a DPDT Switch?

    double pole, double throw. has 6 terminals, in 2 columns of 3. 3 positions, one for each pair of terminals. center position=no connection; upper pos. = upper pair connected to center pair; lower pos. lower pair conn. to center pair. the columns are isolated from eachother so never connect


    243) Would a GFCI preform properly if fed by a 12/2 SPT-2 (Zip Cord)? Why or why not?

    yes, it will work; it measures the load side for leaks to ground, so as long as the load has a ground wire it will work, but the line side does not need to be grounded

    255) How many volts does analog run off of?

    10


    259) Rubber such as the jacket of wire has bad chemical resistance to two things, which are they? Acids, Alcohol, Caustic Bases, Gasoline, Grease, Kerosene, Oil, Solvents, or Water?

    oil and gas


    280) If the show lights suddenly dim, and it is not from the power company because it is only your lights, what is this an indication of and what will probably happen next?

    indicates the end of a scene, usually leads ot applause


    281) What is the minimum amount of twists on a pigtail splice for a good connection?

    guess is 3


    288) Of the two Strain Relief Inserts in a Bates plug with a flat and rounded side to each, describe the quantity and position of them when using 14/3 SJ wire, 14/3 SO, 12/3 SJ, 12/3 SO, and 16 ga heat wire in a fiberglass sleeve.

    see the little square paper included with each plug (it's been a while since I have)


    299) What is the difference between MTW, THHN, and TW wire?

    besides the number of letters? MTW is Machine Tool Wiring, moisture, heat, and oil resistant; THHN is heat resistant; TW is moisture resistant; all are thermoplastics


    302) If the Diversitronics strobe is 3,000 watts, why is it permissible to use a L6-15 plug on it?

    the lamp is at a lower voltage

    <hr>

    There are a few I'm too lazy to look up right now.
     

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