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Thread: What did I do wrong?

  1. #16
    Aspiring Old Fart, EE, computer & networking geek Mikey's Avatar
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    Aw, come on. Spring for a $10 meter and at least check to see if the breaker is bad. Only problem might be that the test is best performed at the breaker, which means you've got to remove the panel cover and thus expose yourself and your loved ones to a bunch of 1952 wires carrying lethal currents and maybe electrocute yourself. And if the breaker IS bad, you'd have to replace it, which is even trickier. Maybe calling a pro isn't such a bad idea after all.

  2. #17
    Retired Defense Industry Engineer jadnashua's Avatar
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    Every homeowner that isn't a total clutz should own a multimeter. If, for nothing else, to see if a battery is any good. A poor substitute is an inductive voltage detecter or a test light.

    Yes, you can hurt yourself, but as long as you don't short the probe tip to something, or touch exposed metal parts of the probe while it's connected to something, it's pretty safe. The things come with some instructions...practice on a battery. Don't use ohms when power is applied, and unless it is autoranging, set the range to something above what you expect to read. Most of the newer meters aren't damaged unless you exceed the maximum it can handle...it will just say overload or something like that if it is on the wrong range (most these days are autoranging). Sears has one on sale this week that includes an inductive voltage probe - you just get it near the thing, and if there is power, it lights up.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #18
    Aspiring Old Fart, EE, computer & networking geek Mikey's Avatar
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    Quote Originally Posted by jadnashua View Post
    If, for nothing else, to see if a battery is any good.
    Keeping in mind, of course, that the meter alone won't tell you much, unless the battery is under load when being tested.

  4. #19
    DIY Junior Member alt's Avatar
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    Thanks everyone. We've found out that one of our new neighbors is a licensed electrician, and he is going to come and take a look for us.

    We will definitely be buying a multimeter to have on hand, but I'm happy to have him help out with this one.

  5. #20
    Electrical Contractor/Instructor jwelectric's Avatar
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    Quote Originally Posted by alt View Post
    We will definitely be buying a multimeter to have on hand, but I'm happy to have him help out with this one.
    If you do buy an electrical testing meter be sure that you also get the proper personal protection equipment to go with it incase something goes wrong when you are testing the electrical equipment!
    click here

  6. #21
    Jack of all trades frenchie's Avatar
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    I have to ask - how much power is that guy testing?
    Master Plumber Mark:

    there is nothing better than the
    manly smell of WD 40 in the air
    while banging away on brass with a chisel and hammer...

    it smells like......victory......

    do not hit your thumb...
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  7. #22
    Computer Systems Engineer jdoll42's Avatar
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    Quote Originally Posted by frenchie View Post
    I have to ask - how much power is that guy testing?
    Probably the same circuit this is on:

    http://my.break.com/content/view.aspx?ContentID=275941

  8. #23
    Electrical Contractor/Instructor jwelectric's Avatar
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    Quote Originally Posted by frenchie View Post
    I have to ask - how much power is that guy testing?
    Can you see the device he is holding? This would tell me that it might be 480 but the voltage does not kill it is the amperage that kills.

    A GFCI device does not open at a certain voltage it opens at 5 milliamps

  9. #24
    Jack of all trades frenchie's Avatar
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    Oh, dear - time for my electricity 101 lesson.

    Isn't power a function of voltage and amperage? Watts = amps x volts (something like that?)

    Just wondering... I've never seen someone suit up like that to check a household panel.


    edit: if you think I can recognize different testers & thereby know anything, you've grossly over-estimated me.
    Master Plumber Mark:

    there is nothing better than the
    manly smell of WD 40 in the air
    while banging away on brass with a chisel and hammer...

    it smells like......victory......

    do not hit your thumb...
    __________________
    Just so everyone's clear: I'm the POODLE in the picture ("french", get it?) The hot woman is my wife.

  10. #25
    I&C Engineer (mostly WWTP) Lakee911's Avatar
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    New Arc Flash requirements require different PPF gear for different voltages and amperages that are available. If I'm not mistaken, for the

    Personally, I think that someone invented this suit and he had nothing to do with it and it just happens his brother was a code writer....

  11. #26
    Electrical Contractor/Instructor jwelectric's Avatar
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    Quote Originally Posted by frenchie View Post
    Oh, dear - time for my electricity 101 lesson.

    Isn't power a function of voltage and amperage? Watts = amps x volts (something like that?)
    Very good Frinchie.

    Now let’s just see what we can have momentarily on a 15 amp circuit using Ohm’s law.
    First for the sake of this problem instead of doing a lot of research on the manufacturer’s device we will just use the rule of thumb that a breaker can carry up to six times it rated amperage for a short time.

    Now let’s see just how much heat energy we have in a 15 amp circuit.
    Watts equals amperage times voltage times the trip curve of the device or;
    15 times 120 times 6 equal 10,800 watts of heat right there where the hand and face are in close proximity.

    This same amount of wattage would equate to 22.5 amps if a voltage of 480 was applied.

    As one can see a 120 volt circuit can do the same damage as a 480 volt circuit under the right conditions.

    Quote Originally Posted by frenchie View Post
    Just wondering... I've never seen someone suit up like that to check a household panel.
    To quote a famous man, P. T. Barnum, “there is one born every day.” I always suit up in a face shield and gloves to remove a panel cover, but then again I have had one explode in my hands. Just about everyone that I know that has experienced something also uses the proper PPE when working on household circuits. It is those idiots that think that they can’t be hurt that take all those unnecessary chances.

    Quote Originally Posted by frenchie View Post
    edit: if you think I can recognize different testers & thereby know anything, you've grossly over-estimated me.
    Oh no my friend, I think that it is the other way, you under estimate your self.

  12. #27
    In the Trades Bob NH's Avatar
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    That kind of personal protection equipment is not required for testing outlets in your home.

    http://www.ien.com/article/selecting-right-amount/7594

    "Non-fire resistant cotton has no arc rating and is only allowable at locations or working distances demonstrating extremely low available incident energy potential. Non-fire resistant clothing, like synthetic blends, is forbidden because it can easily ignite and/or melt into the skin and aggravate a burn injury. The best rule of thumb is that things change dramatically for a worker once he or she enters the flash-protection boundary (defined by NFPA 70E-2004 Article 100-1 as an approach limit at a distance from exposed live parts within which a person could receive a second-degree burn if an electrical arc flash were to occur). As the incident energy level increases, the Hazard/Risk Category (defined by NFPA 70E-2004 Article 100-1 as the amount of energy impressed on a surface a certain working distance from a source generated during an electric arcing event) increases as well."

  13. #28
    Electrical Contractor/Instructor jwelectric's Avatar
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    Bob,
    Just to clarify what my intentions were with the picture of the man in the suit was more along the lines of humor than anything else but being that you bring up the subject of home receptacles I think a little more explanation is now called for.

    When testing a receptacle that is not removed from its enclosure there is no approach to live parts as the device itself stops close approach to live parts.
    The original post would require the person to remove the fixture and this now allows approach to live parts if the person is doing a voltage check and would now require some type of secondary protection.

    Couple this with the fact that this person might not have any training on the use of an electrical testing meter or the danger of the circuit being worked on and we have a very dangerous situation.

    Should this person go out and buy a cheap multi-tester that has no rating and not have the meter properly set it is very possible that the meter itself could explode in their hand.

    As outlined in NFPA 70E PPE should be worn even when testing batteries.

  14. #29
    In the Trades Bob NH's Avatar
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    Quote Originally Posted by jwelectric View Post
    As outlined in NFPA 70E PPE should be worn even when testing batteries.
    jwelectric,
    I'm sure you have access to NFPA 70E, which I do not have.

    Maybe you can provide the table, or a link to it, that is referred to in the text from the link in my previous post. It takes a lot of energy to produce 1.2 calories per square cm which is apparently the lower limit of where flash protection is required.

    It would be of value to people to know what the NFPA 70E levels of protection would be for working on household systems that are protected by both a main and branch circuit breakers of various levels.

    It is important for people to be protected, but it is also important to not try to scare people by suggesting a big risk where little or no risk exists.

    QUOTE FROM LINK IN MY PREVIOUS POST:
    It's best to refer to NFPA 70E-2004 for complete clothing requirements, but here are the basics for each Hazard/Risk Category:


    • Category 0: One layer of untreated natural fiber clothing; no minimum PPE Arc Rating (cal/cm²).
    • Category 1: Fire-resistant shirt and fire-resistant pants; one total layer. Minimum PPE Arc Rating: 4 cal/cm².
    • Category 2: Category 1 plus cotton underwear; two total layers. Minimum PPE Arc Rating: 8 cal/cm².
    • Category 3: Category 2 plus fire-resistant coverall; three total layers. Minimum PPE Arc Rating: 25 cal/cm².
    • Category 4: Category 2 plus multilayer flash suit; four total layers. Minimum PPE Arc Rating: 40 cal/cm².
    Non-fire resistant cotton has no arc rating and is only allowable at locations or working distances demonstrating extremely low available incident energy potential. Non-fire resistant clothing, like synthetic blends, is forbidden because it can easily ignite and/or melt into the skin and aggravate a burn injury. The best rule of thumb is that things change dramatically for a worker once he or she enters the flash-protection boundary (defined by NFPA 70E-2004 Article 100-1 as an approach limit at a distance from exposed live parts within which a person could receive a second-degree burn if an electrical arc flash were to occur). As the incident energy level increases, the Hazard/Risk Category (defined by NFPA 70E-2004 Article 100-1 as the amount of energy impressed on a surface a certain working distance from a source generated during an electric arcing event) increases as well.

    Section 130.3(A) of NFPA 70E-2004 includes equations that can be used to calculate flash-protection boundary distances for systems operating at 600 V or less. Flash-protection boundary for systems operating at above 600 V is characterized as the point where the incident energy level equals 1.2 cal/cm². It also provides a method that requires little or no calculation -- a table in Section 130.7(C)(9)(a) with Hazard/Risk Category values for typical work tasks for common equipment is available. These Hazard/Risk categories are estimates based on actual calculations, but strict attention should be paid to footnotes referenced in the table. The categories are conservative and in many cases will overstate the requirement. A worker can simply find the appropriate work task in the table, but for system conditions that fall outside the defined fault current ranges and fault clearing times, the tables should not be used to choose PPE. Additionally, for some conditions that do fit the system, the recommended PPE may be inadequate.

  15. #30
    Electrical Contractor/Instructor jwelectric's Avatar
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    Bob

    There are a lot more dangers to the untrained person than just the arc flash. One of which I already mentioned was the misuse of an electric testing meter where the testing device itself comes apart in ones hand. This is something which I witnessed myself when a home owner was testing the continuity of a heating element on a water heater while the circuit was still energized. The $8 tester was not fused and he received some bad burns as well as being cut by flying parts.
    130.4 of NEC 70E clearly states that no one should perform testing procedures on a voltage over 50 volts unless they have had the proper training on the use of testing equipment. I don’t believe that reading the users manual would fulfill these requirements.

    In NEC 70E using the 2004 Edition on page 25 it gives the approach boundaries to exposed live parts at which point a person is in danger of being hurt. For free conductors such as the conductors in the light box the limited approach boundary is 10 feet and the restricted boundary is, avoid contact.

    In lieu of the calculation Table 130.7(C)(9) can be used;


    Notice that for panelboards rated 240 volts and below when testing equipment is being used that the risk category is 1 and voltage rated gloves are recommended as well as voltage rated tools.

    I am not trying to instill fear where fear should not be instilled but instead trying to let the original poster know that there is a grave danger in working on electrical circuits without the proper knowledge of what they are doing. It is very important that they realize that there are over 30,000 people each year that receive medical attention due to shocks alone.
    There is the danger that a slight shock could cause someone to fall from a ladder and get hurt.

    Electricity is a silent killer that has no smell sound or visual warnings. When you feel it, it is way to late.

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