The above Ad will no longer appear after you Sign Up for Free!

Learning electrics/electrical safety

Discussion in 'Sound, Music, and Intercom' started by miriam, Dec 5, 2007.

  1. miriam

    miriam Active Member

    Messages:
    102
    Likes Received:
    2
    Location:
    Up the wall
    I would like to learn about electrics in terms of in theaters and doing live shows not in theaters (like in a room).

    What sort of person should I look for, to convince them to teach me? What sort of topics should be covered?

    If anyone has taken such a course, and can give me the syllabus, that would be fabulous.

    Thank you for your help.
     
  2. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

    Messages:
    4,425
    Likes Received:
    2,814
    Location:
    Las Vegas, NV, USA
    miriam, here's probably the best syllabus available, taken from ESTA's ETCP Entertainment Electrician's Exam Content. But, and I mean no disrespect, it's far too advanced for your needs, many people's needs for that matter. Other than the sound class you're already taking, I'm unable to recommend an alternative, unless there's a comparable lighting class at the same or similar institution. I would advise against learning from a "real" (commercial/residential) electrician, as the entertainment field is too specialized and much of the equipment we use on a daily basis they have never seen.

    Your quest for knowledge is refreshing, but remember you can't learn it all at once. Continue to start threads and ask questions, and I've noticed you answering some--that's what ControlBooth is all about!
     
  3. avkid

    avkid Not a New User Fight Leukemia

    Messages:
    5,948
    Likes Received:
    225
    Occupation:
    Stagehand/ Production Company Owner
    Location:
    Howell, NJ
    Ehh.... some of the basic things are always the same and a good commercial or heavy industry(not residential) electrician can be useful, for a while anyway.

    Go buy some books about basic electrical theory.
     
  4. mixmaster

    mixmaster Active Member

    Messages:
    274
    Likes Received:
    23
    Location:
    Iowa
    Miriam,
    Electricity as it applies to theater is a wide ranging subject. Available electricity is probably the 2nd most limiting factor in designing a lighting system outside of a traditional performance space. Poor electricity can also wreck havoc in a sound system. Electricity is a creature to be respected but not feared.

    Understanding basic AC fundamentals is a nescesity. You have to be able to figure out how many instruments you can plug into a dimmer, how many dimmer packs can be plugged into a wall outlet, and where is the circuit breaker or fuse if you go beyond those numbers. It also helps to know what the colors of the wires mean in basic circuits so you don't connect a black wire to a green wire. Understanding the difference between 110 220 and 208 3phase will also be helpful. All of this is basic AC stuff and any qualified electrician can help you with this. A textbook from a high school or collage "introduction to electricity" class would have all of this information also.

    More advanced AC stuff is necessary in the sound world as you start hooking up speakers. Amps have impedance (the AC version of DC resistance) ratings, speakers interact in terms of phase and amplitude, and level matching between pieces of equipment is done in volts. Most of this type of stuff is covered in Basic Electronic classes and texts. I still have, and occasionally reference, my college texts Electronics Fundamentals, Circuits Devices an Fundamentals by Floyd and Grob Basic Electronics

    As to specific questions you should ask, learn the following terms: volts, amps, watts, and ohms. Everything revolves around them. Also look up and learn Watt's Law and Ohm's Law. Learn how to apply them and manipulate the equations. You also need to understand the concepts of capacitance, inductance, resistance and impedance. Take time to learn the color codes for rating resistors. Learn how to use the decibel.

    Lastly, I will offer some advice. First, GROUND EVERYTHING, EVERY TIME. DON'T LIFT THE AC GROUND ON ANYTHING, EVER. It's there for you safety but doesn't work if you don't hook it up.
    Second, I learned this the hard way. NEVER ASSUME THAT A CIRCUIT IS DEAD. If you are going to work on something, turn it off and lock it out yourself. Take no one's word for it. Then test the circuit to make sure it's dead before you touch it. Circuit testers are cheap, hospitals stays and funerals are not.
    Electricity is a fun world if you respect it and stay safe
    Best of Luck
     
    miriam likes this.
  5. museav

    museav CBMod CB Mods Departed Member

    Messages:
    4,017
    Likes Received:
    562
    Occupation:
    Acoustical, audio and audiovisual consultant
    Location:
    Marietta, GA
    Just to show how confusing this can get, the AC version of DC resistance consists of impedance (the real component) and reactance (the imaginary component). It is often the fact that devices like speakers are not a pure imedance load and have reactance that must be considered.

    On the point of ground everything, that is definitely true but this also has to be proper grounding. Multiple grounds can actually have voltage differential between them and in the case of sound systems it is often having multiple grounds rather than a single common ground that causes problems. Everything is grounded, just in a manner that potentially introduces audio problems.

    Here is a very good reference for audio power and grounding, http://www.middleatlantic.com/pdf/PowerWhitePaper4_07.pdf. You can also sign up for a version that will get updated as this document is indeed updated when any problems are found or additional information is available.
     
  6. miriam

    miriam Active Member

    Messages:
    102
    Likes Received:
    2
    Location:
    Up the wall
    I want to get to the point that I can set a basic system up myself with the confidence that, barring the direct hand of God, I will not cause a dangerous situation. Myself, like without a qualified electrician there with me. Are setting up speakers by myself way in the future? I mean besides the heaviness, I would do it with someone else. But hooking up speakers and amplifiers without an electrician is something I should definitely avoid right now?

    Thank you for everything you mentioned, I guess I will begin with the vocabulary and equations, and try to find a book on basic electricity. We will see how far that takes me.

    Is the ESTA exam level like a specialty? Or is it something every competent sound person knows? Or needs to know?
     
  7. avkid

    avkid Not a New User Fight Leukemia

    Messages:
    5,948
    Likes Received:
    225
    Occupation:
    Stagehand/ Production Company Owner
    Location:
    Howell, NJ
    No, you don't need an electrician to do that.
    Just a person who can read spec sheets and use a multimeter.
     
  8. mixmaster

    mixmaster Active Member

    Messages:
    274
    Likes Received:
    23
    Location:
    Iowa
     
  9. museav

    museav CBMod CB Mods Departed Member

    Messages:
    4,017
    Likes Received:
    562
    Occupation:
    Acoustical, audio and audiovisual consultant
    Location:
    Marietta, GA
    That's what I get for typing without thinking. You are correct, I used impedance where it should have been resistance, AC impedance consists of a resistive real component and a reactive imaginary component. But relating AC impedance to DC resistance is really somewhat misleading and can cause one of the more common errors. AC impedance is more complex (pun intended) and if you try to measure AC impedance with a DC Ohmmeter, you will often get incorrect values.
     
  10. icewolf08

    icewolf08 CBMod CB Mods

    Messages:
    4,077
    Likes Received:
    681
    Occupation:
    Controls Technician - TAIT Towers
    Location:
    Lititz, PA
    Hooking up speakers and amplifiers is something you can do yourself, save for lifting them if they are too heavy. Most high school students in the US have done it before, especially ones that play in bands or work in theatre. They may not know why it works, but they know how to make it work (for better or worse), and they lear by experience until someone teaches them otherwise (and they go on doing it their way...).

    As far as the ESTA ETCP Exams go, it is a specialty certification. I believe in theory only the top 10% of all entertainment technicians meet the requirements of the exam. A technician who holds an ETCP certificate theoretically has years of experience and knowledge and is at the top of his or her game. The ETCP certificate is not something you need to have in order to be hired, though it does make you look better.

    On to your education. Read as much as you can get your hands on. Take classes if they are offered. If you can swing a study abroad program, come to the US and get yourself in one of the theatre schools here for a year. The thing about learning about electricity is that you don't really want to learn by experimentation. Playing with electricity can be very dangerous. Learning by experimentation with say sound is less hazardous to your health in that in most cases you are more likely to destroy equipment (which can be replaced) rather than yourself.

    In terms of lighting design, I am sure that we can help you out with that, and there are many good books. There are plenty of self taught lighting designers who do just fine. I believe we have some pretty good threads about the design process, you will just have to search for them.
     
  11. mixmaster

    mixmaster Active Member

    Messages:
    274
    Likes Received:
    23
    Location:
    Iowa
    Brad,
    After rereading my last post, I can see how it could be misleading. I included DC resistance as a component of a speaker's impedance because if you use a DC ohmmeter to meter a speaker when it is out of circuit you will get a reading. Odds are, it wont match the information in the specs but there is resistance in the voicecoil of the speaker. Since you would be measuring the speaker at rest there would be no reactance and the result would be pure resistance. Just like a resistor in a DC circuit. The difference between the measurement taken above and the stated spec is the reactive part of the impedance figure. I check speakers this way occasionally. If my meter shows a (DC) resistance across the coil, within 2 ohms or so of the stated spec, the speaker is usually good. Shorts, opens, or values beyond +/- 2 ohms are usually bad.

    ANYWAY, I think you and I are headed in the same direction just using different words. Either way, I suspect we have gotten beyond the scope of the original post. I hope no-one minds the slight hijack. It's been a good conversation.
     
  12. Traitor800

    Traitor800 Active Member

    Messages:
    146
    Likes Received:
    21
    Location:
    Lititz, PA
    Impedance is actually the transformed combination of the resistance, capacitance, and the inductance of a system, basically its a method of combining the resistance, capacitance and inductance into values that can be manipulated algebracially when modeling or analyzing a system instead of using derritaves
     
  13. cutlunch

    cutlunch Active Member

    Messages:
    522
    Likes Received:
    21
    Location:
    Auckland, New Zealand
    Miriam
    There have been some good comments but I also think a number of people have confused the issue.

    As far as plugging in a sound system unless it is a very large system for over 5000 people you don't have to really worry.

    If you can plug your radio, toaster, TV, heater into the power points at home you are half way there.
    At your basic level there are two main things to worry about.
    Electrical Safety
    Electrical Load your drawing

    1) Electrical safety
    Do a visual check off all your electrical leads, plugs, and sockets before you plug things in.
    Things to look for are:
    Main electrical socket you plug into : any of the socket damaged / cracked exposed metal that you don't see normaly or scorch marks on the plastic then you need an electrical contractor to check it is safe and do any repairs. The same with the power leads on the sound gear and extension leads.
    Once again any damage to the plugs, cracks, missing plastic, has the outer insulation pulled back from the plug so you can the individual coloured wires inside . Once again if in doubt get a qualified person to fix them.

    Also if a piece of equipment starts to smell while you are using turn it off.

    Testers as have been mentioned can help check points are working. But another simple tester is a desk lamp it gives a quick indication of whether the power is on or off.

    2) Electrical Load
    Each piece of sound gear you have that plugs into electricity should have a current rating in amps on it. You add up the total amps for all equipment you are wanting to use on electrical socket, (power point) and make sure that doesn't exceed the number of amps

    I don't know what the standard is for Israel. Your parents might be able to tell you. Or you could ask the electrician ( electrical contractor) that looks after this side of things at your school. The things you need to ask him is "how much current can I safely draw from the power points that we have at school, at home , in businesses" He should be able to tell you this and you should then take the lowest current rating in amps as the base figure when working out if all the sound gear can work off the same plug.

    Most of the time you won't draw the maximum current for that circuit.
    Another thing to remember is don't turn all the sound gear on at the same time. By this I mean if you have a mixing desk, amplifier(s), powered monitors etc. This is because electrical equipment especially amplifiers draw more current when they first startup then when they have been turned on for a few minutes. If everything is turned on at once you may blow the circuit breaker for that circuit. Also to help minimise damage to your loud speakers from loud pops follow this sequence.
    Turn on:
    1) Mixing desk
    2) CD / tape player
    3) Any sound processing equipment.
    4) Finally the amplifiers driving the loud speakers
    Two and three are interchangable.

    Turning the gear off do it in the reverse order - with amplifiers first.

    Just in general be aware you are using a different voltage ie 230 volts compared to the US 110 volts. Also they use 20 amp circuits where yours are more likely to be 10 -16 amps. Also the States have a lot of old systems mixed together with different plugs and current ratings.
    So it pays to check with someone whos has knowledge in your country.

    There some people on Control Booth who should not comment about electricity because they either lack knowledge or are suggesting people do things they are not trained for. Then there are others who are very safe when it comes to electricity. The best thing for you to do is find someone near where you live who knows about electricity. It maybe the electronics teacher or electrician who does it for a living. Then get them to mentor you. Remember you should be fine just plugging in the sound gear but when something appears wrong get experienced help. For instance I would expect you to be able to check whether the power switch on a piece of equipment was on and off. Also using another piece of equipment to check if the power is on at the plug. But if you check this and still the equipment doesn't go this is when you need experienced help. For the basics this may be an older sound tech but never open up a piece of electrical equipment your self.

    If things get confusing you can PM me and I'll try to clear it up.
     
  14. avkid

    avkid Not a New User Fight Leukemia

    Messages:
    5,948
    Likes Received:
    225
    Occupation:
    Stagehand/ Production Company Owner
    Location:
    Howell, NJ
    [​IMG]
    "An Israeli three pin Plug. This plug, defined in SI 32, is unique to Israel and is incompatible with all other sockets. It has two flat pins like the American plug, but they form a V-shape rather than being parallel. Rated at 16 A, it also has an earthing pin. Visitors to Israel will find that in practice, sockets are manufactured with widenings in the middle of the V-shape-oriented slots for the energised prongs. This allows the Israeli socket to accommodate European 2 pin plugs."
     
  15. cutlunch

    cutlunch Active Member

    Messages:
    522
    Likes Received:
    21
    Location:
    Auckland, New Zealand
    Avkid this is the right plug but according to other sources this one overheats when drawing loads near the limit of 16 amps due to the flat pins. Apparently they now have a version of this with round pins that handle the current better. They are now making sockets that can take both flat and round pins.

    Here is the link.

    http://en.wikipedia.org/wiki/Domestic_AC_power_plugs_and_sockets#Type_H_.28Israeli_3-pin.29

    I am glad our plugs have been fairly standard for decades.
     
  16. miriam

    miriam Active Member

    Messages:
    102
    Likes Received:
    2
    Location:
    Up the wall
    So it should be okay for me to set up a simple system if it all looks okay, if there is an electrician on the premises. But he does not have to be right there. And be careful to power up amps separately, and not to exceed amperage (that is the word, correct?) for a power point. And check outlets, cable connecions, etc. before plugging anything in.

    And I won't set anything up for 5000 people by myself at this point:mrgreen:

    And I need an electrical theory book and a mentor (regular electrician or theatrical?).

    Right now I do not have formal class until I get more live experience, so I am trying to decide what my next step is.

    Thanks, everyone.
     
  17. cutlunch

    cutlunch Active Member

    Messages:
    522
    Likes Received:
    21
    Location:
    Auckland, New Zealand
    Miriam for basics you don't need an electrician on site with you. You only need them when there is a problem. The main thing is to learn to recognise when there is a problem. The mentor could be from the theatre or a qualified electrician. The main thing is they teach you how to do things safely. At this stage you don't really need to know how to rewire a power lead.

    If you follow the things you have said in your latest post you will be right. And yes amperage is the right word. It just comes downs to commonsense which you seem to have plenty of.

    As far as getting more experience approach people in theatres near you and see if you can volunteer to help the sound guys. Depending how far away they are from you, talk to the sound guy you worked with on that Wednesday when you did the sound for the singer. If they are to far away maybe ask them if they know anyone closer that might help you. Help out with as many things at school as you can. You'll pick up the basics from the senior technicians.
     
  18. cutlunch

    cutlunch Active Member

    Messages:
    522
    Likes Received:
    21
    Location:
    Auckland, New Zealand
    No offense Charcoaldabs but from a number of things you have said, before you do any more electrical wiring I would suggest you get a mentor. Those leads you wired for your school where you think you crossed the neutral and phase are an example. Yes they may work but they can also lead to electrocution, this is quite often happens when there is more then one fault in the wiring. And remember you don't know if the person before you made mistakes as well. Even if the conductors all had the same coloured insulation a quick test with a multimeter set for continuity would have shown you that you had swapped the phase and neutral wires at one end.

    I am not trying to pick on you but show that sometimes learning things from the internet is not always the best way especially with something like electricity. Find a mentor maybe a teacher or a electrical contractor. A local technical college should have some part-time or block courses you can do on basic wiring of plugs and leads.

    Your question about the grounding of European plugs does seem to indicate that you may not fully understand the two main ways electrical appliances are wired.

    For the type of appliances found in your home and most sound gear you use you will come across two types of wiring.

    The three pin system where you have neutral , live and ground pins. This has to be used with equipment where it is possible for any of the power wires to come into contact with any part of the appliance in a fault condition. Such as a metal case. Basically if the operator of the equipment could touch a piece of the equipment that may be live. There needs to be a ground wire to take the fault current and blow the fuse or a circuit breaker before the fault current could flow through the operator to ground giving them a possibly fatal electrical shock. Most power amplifiers we use are of the grounded type.

    The two pin system works with what is called double insulated appliances. The European regulations also require this to be used only appliances drawing no more then 2.5 amps of current. Double insulated means basically that there are at least two layers of insulation between the power wires and the person operating the equipment. So there would have to be a bad fault to let the operator come into contact with live electrical wires. Basically the appliance would have to had it's case physically smashed. Examples of these types of appliances are electric razors, portable music players- ghetto blasters etc.

    Please don't flame me because you think I am being unfair to Charcoaldabs. I am only worried that he might put himself in a dangerous situation due to lack of knowledge. In other areas I always enjoy his contributions to ControlBooth.
     
  19. avkid

    avkid Not a New User Fight Leukemia

    Messages:
    5,948
    Likes Received:
    225
    Occupation:
    Stagehand/ Production Company Owner
    Location:
    Howell, NJ
    I was actually going to say something like that, but yours came out much better than mine would have.
     
  20. icewolf08

    icewolf08 CBMod CB Mods

    Messages:
    4,077
    Likes Received:
    681
    Occupation:
    Controls Technician - TAIT Towers
    Location:
    Lititz, PA
    We tell him all the time he needs better supervision....

    I am going to repeat a couple things and maybe add something new. As cutlunch said, you should not worry about setting up the sound systems that you are learning to set up. The equipment is designed so you can do it safely, and a little common sense will let you know if you are about to do something unsafe. As was mentioned before, burned connectors, exposed wires, etc. will tell you very quickly that something isn't quite right and you should not continue to use the affected equipment.

    Ultimately the same goes for lighting. As has been proven by many of our high school age members, you don't have to know much to make the lights work. Everyone knows how to plug in a light, you probably do it at home all the time, but you wouldn't plug it in if it looked unsafe. Same applies to theatre lighting, if a connector is melted or wires are showing you don't use it. Then, as long as you know how to turn on the lighting console you can probably get the lights on.

    If it is basic work you are starting out with, you will be fine. Keep the common sense in gear and you may not get perfect results, but you will live to learn another day. One of the biggest rules is never do anything you feel uncomfortable doing, if your gut tells you a piece of equipment looks bad or that you shouldn't climb out on the flimsy board over the stage, don't. It is better to sacrifice part of the show than your life or health.
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice