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  1. #1
    Join Date
    Jul 2011
    Location
    Locust Grove, Ga
    Posts
    60

    Electrical Troubleshooting

    Any general tips on using meters in the field. I'm in tech school studying the electrical part and not getting it yet. Just curious on any advice I can get. Thanks.

  2. #2
    Join Date
    May 2004
    Location
    Frederick, MD
    Posts
    921

    Don't

    go cheap. Get a quality professional grade multi-meter. Keep the batteries fresh. Always test your meter with a known source (voltage) to verify it's working properly.

  3. #3
    Join Date
    Aug 2011
    Location
    North West FL
    Posts
    97
    You must know what you are touching with your leads. I have melted a few leads when my tip slipped and shorted. Hands on is a great, fast way to learn. Try using a meter on something you know. That way you can understand what you meter is telling you. If you can, get someone who knows what they are doing. They can keep you safe and maybe show you some tricks.
    I use a fieldpiece hs33 stick meter. It's easy to use and easy to understand. I only wish I had the one with the backlit display.

  4. #4
    Join Date
    Jan 2006
    Location
    McQueeney, Texas
    Posts
    3,708
    I could write a book- a small one, but none the less- a book.


    Biggest I can think of is make sure the meter is working before trusting it when checking for voltage!! Not only testing by doing the ohms test- but actual known live voltage.

    Make sure your on the right setting (Volts, ohms, MV, MA- etc).

    You don't want nicks in the leads/wires.

    Keep batteries handy.

    I discharge caps before I test them whether they need it or not.

    Wire connections have been known to come loose and fly around while checking- I make sure, especially when I am soaked in sweat, I never am touching the unit at the same time if possible- increasing my resistance.

    Use a backup meter if you have doubts.

    They will teach you about getting volt readings on open circuits, voltage when there should be none, ghost volts, getting 240v readings on one leg to ground which seams impossible (single phase), and all that stuff that will send your mind wondering all over the laws of physics. LOL.

  5. #5
    Join Date
    Dec 2002
    Location
    SouthEast NC ICW & Piedmont Foothills
    Posts
    7,635
    1- you can't read voltage across a closed switch

    2- use your meter to verify the power is OFF before grabbing any wires

    3-you don't need top of the line meter before you know how to use it

    4-start at one point and work your way from there, don't jump around wildly

    5-
    It`s better to be silent and thought the fool; than speak and remove all doubt.

  6. #6
    Join Date
    Aug 2011
    Location
    Ohio
    Posts
    49
    Any time I work with capacitors that have been in the system or even out for that matter, I always read voltage before anything else. Not only will this tell you if there is a potential shock hazard before you touch it, you will also discharge the cap from just reading voltage. I just keep the leads on until it reads zero then I know I am good.

    Oh and just a general electrical tip. Don't make it a habit to just memorize what wire goes where and wire colors. These are are important but it is better to understand sequence of operation. If you understand what is supposed to happen and when you can engineer the circuit from your head so it doesn't matter if what you are working on is different than what you memorized. Understand how ladder diagrams/ schematics work and practice drawing them. If you can lay the circuit out on paper from you head then you will be able to build it in practice.


  7. #7
    Join Date
    Oct 2010
    Location
    Baton Rouge, LA
    Posts
    1,110
    Continuity and resistance are your friends. Learn when you need to use them, which one, and why.

    Your best friend is knowledge of the electrical component and how the physics of that component work.

    A good place to start is http://www.parallax.com/tabid/234/Default.aspx

    You can learn a lot following the lessons of that kit.
    If you're too "open" minded, your brains will fall out.
    Artificial intelligence is no match for natural stupidity.

  8. #8
    Join Date
    Jul 2011
    Location
    Lehigh Valley, PA
    Posts
    427
    To be proficient with a VOM in the field, you really have to understand circuits first. For example, understand the low voltage circuits and related components and high voltage circuits and its components. Understand the difference between 24vac, 208-220/240, 1p & 208/240/480 3p. Know what you are measuring and why you want to test a connection.

    Learn Ohm Law. While it is rarely used, a solid understanding will help you understand the difference between Resistance, voltage, amperage & watts.
    Try and learn how to read basic schematics.

    Think of high voltage electricity like a faucet. Faucet closed, you have pressure but no flow. This is voltage. Faucet open and flowing, this is voltage & amperage.

    Working on 12DC auto circuits can help you learn low voltage circuits and it is much safer to mess around with.

    I've been messing with electric since for 35yrs and I still don't know it all. But it's one of my favorite things to do.

  9. #9
    Join Date
    Sep 2011
    Location
    Canada NB
    Posts
    32
    HI DOG1,,,,First get a good meter with quality leads,,never work with broken or cracked leads,,double check your meter on a source you are sure it is live,avoid very wet locations,,wear leather gloves if you have to,,always keep hands dry and wear dry gloves in wet locations,,do not take chances on live circuits,,It is better to take power of than getting buzzed,,Stand clear of new changes {just in case you made a bad connection somewhere,,If the disconect for the main power is not close to you make sure to lock it up,,just in case someone has the idea to turn it on,,Safety first is very wise decision,,,You have greater chances to get zapped by an electrical shock than winning a lottery,,,hehehe Get a good meter,,be carefull,,and good luck,,Jocelyn

  10. #10
    Join Date
    Jul 2011
    Location
    Locust Grove, Ga
    Posts
    60
    Thanks everyone for the great advice. I can tell guys on here really know their stuff, this website is like having all kinds of friends in the industry. I'm 40 years old, but I know I'm going to be green for a long time, and that's ok. I just want to learn as much as possible because my life depends on learning this new career. I bought a Fluke 116/322 HVAC combo kit and I already had a Fluke non-contact voltage tester, I'm just ready to learn how to use all my new tools. In class they have me check amps with the clamp on, and voltage with the leads, but I just don't know what the readings mean and why I'm doing it. I know we will get around to it but it's just not happening quick enough. One student in class with several years of experience says he doesn't bring his pressure gauges out of the van half the time. They all say it's usually electrical. Anyway, thanks again.

  11. #11
    Join Date
    Nov 2006
    Location
    Southeastern Pa
    Posts
    17,838
    Apply for Pro membership. 15 quality posts and a real hvac student status and you're in.

    That way you can ask tech questions in Pro Residential and Pro Commercial. That's where the good stuff is.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

    AOP Forum Rules:







  12. #12
    Join Date
    Nov 2010
    Location
    N. Idaho
    Posts
    586
    Quote Originally Posted by walterc View Post
    Not only testing by doing the ohms test-
    Whats the "Ohms test"?

    Dont think I have heard this term.

  13. #13
    Join Date
    Aug 2011
    Location
    Ontario
    Posts
    381
    I can only tell you what helped me to understand things when I first started. You must first uderstand the sequence of opperation of the equipment you are working on. Then follow the Turkey.
    Get into Pro, lots of help there.
    Good luck.

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