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Thread: reduced voltage at outlets, and ground test question

  1. #16
    Retired Defense Industry Engineer jadnashua's Avatar
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    If it was in focus or didn't have the glare, it would be easier...

    If the range/mode scale is on 250 or say 25, look for a scale that ends up at 250 and read those values. So it it went from 0-25, 10 would be 100 if the knob was on 0-25.
    Jim DeBruycker
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  2. #17
    Master Plumber Redwood's Avatar
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    The red scale just below the mirror would correspond to AC and the black scale just below the mirror would correspond to DC.
    The numbers below would be used for both by using whichever range was selected.

    The scale at the top is ohms and the one at the bottom is db.

  3. #18
    DIY Senior Member mnalep's Avatar
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    I tried to take a better picture, but could not improve on the one above - so I read that picture into PAINTBRUSH, and tried to DRAW the numbers that are on the dial face of the multimeter. (I also drew in about where the needle was as the black line)

    The red AC scale has no numbers below it, and only says AC at the beginning and end of the range scale.

    The 4 DC scales are below the red AC scale.

    (OHMS in green, and dB in black at the bottom)

    So you are saying that if the needle lined up under the RED mark that is just above the '1' mark on the DC scale, and if the AC dial was on 250, then I would interpret that as 1/5th of 250 - 50 AC volts? (Likewise if the dial was set on 50 AC, the needle in the same place, then I'd interpret that as 1/5th of 50 - 10 AC volts?)

    PS: I totally don't understand the sensitivity, OHMS/Volt, and resisitance you wrote about?
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    Last edited by mnalep; 11-23-2008 at 07:32 PM.

  4. #19
    Master Plumber Redwood's Avatar
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    What I'm saying is that the lines in red are for AC and the lines in black are for DC.

    The numbers below are for either the red or black scale. It is the use of the red or black graduations that are important.

    If you are set on the 0 - 250 volts the number scale below used would be the 0 -25 scale with a "0" added to the reading.

    If you are set on the 0 - 50 volts the number scale below used would be the 0 - 5 scale with a "0" added to the reading.

  5. #20
    DIY Senior Member mnalep's Avatar
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    Hey Redwood,

    I think I got it now. Thank you.

    If I understand correctly, then where I drew the needle would be read as:
    10 volts if I my dial is set on the 50.
    50 volts if the dial is set on the 250.

    ? 2 volts if the dial is set on 10 ?
    ? 200 volts if the dial is set on 1000 ?

    PS: So how would I interpret if I was reading DC voltage? (My settings on the DC voltage dial are 5, 25, 125, 500/1000).

  6. #21
    Master Plumber Redwood's Avatar
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    You would then use the black graduations and apply the numbers pretty much the same way. Pick the number scale thats close and add "0's" as needed.

  7. #22
    Plumber Cass's Avatar
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    WoW...you can make life much easier if you go to a big box store and buy a voltage tester that looks something like this



    Then start at the main pannel...find the problem circuit...and trace it back until you find the problem...You may find a tester like the one above is easier to use and safer...

    Better still call an electrician to trouble shoot it for you...like jwelectric below is inferring...he may be right about the outcome...
    Last edited by Cass; 11-24-2008 at 06:12 AM.

  8. #23
    Electrical Contractor/Instructor jwelectric's Avatar
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    If this dude doesn't know how to read the meter he is using pray tell me why are we trying to tell him how to put his hands into something that could kill him?

    Just which of us is more stupid? The guy not knowing or us trying to help him kill himself?

  9. #24
    Master Plumber Redwood's Avatar
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    Quote Originally Posted by jwelectric View Post
    If this dude doesn't know how to read the meter he is using pray tell me why are we trying to tell him how to put his hands into something that could kill him?

    Just which of us is more stupid? The guy not knowing or us trying to help him kill himself?
    I would tend to agree...

  10. #25
    DIY Senior Member mnalep's Avatar
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    Quote Originally Posted by jwelectric View Post
    If this dude doesn't know how to read the meter he is using pray tell me why are we trying to tell him how to put his hands into something that could kill him?

    Just which of us is more stupid? The guy not knowing or us trying to help him kill himself?
    jwelectric,

    "DUDE", I appreciate you looking out for my well being. But please do not discourage the people here from answering my questions.

    The fact is that I may not know exactly if my multimeter is telling me there is 25 volts, or 50 volts on a line - but I DO understand there is voltage in the lines - and I am not going to put my hands on any line, with any voltage, in it!

    Also, if the instruction booklet that came with this meter, was written with any clarity at all, or even just an example, I would already know how to read the meter.

    If those with experience stopped training those without experience, how would we ever get new electricians, policemen, or any other profession where a 'learner' could get injured. No one would ever learn how to do things for themselves, or around their home or automobile.

    We all have to learn somewhere.

    Please don't discourage people from helping others, or answering questions on this forum.
    Last edited by mnalep; 11-24-2008 at 07:51 AM.

  11. #26
    Plumber Cass's Avatar
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    Quote Originally Posted by mnalep View Post
    jwelectric,

    "DUDE", I appreciate you looking out for my well being. But please do not discourage the people here from answering my questions.

    The fact is that I may not know exactly if my multimeter is telling me there is 25 volts, or 50 volts on a line - but I DO understand there is voltage in the lines - and I am not going to put my hands on any line, with any voltage, in it!

    Also, if the instruction booklet that came with this meter, was written with any clarity at all, or even just an example, I would already know how to read the meter.

    If those with experience stopped training those without experience, how would we ever get new electricians, policemen, or any other profession where a 'learner' could get injured. No one would ever learn how to do things for themselves, or around their home or automobile.

    We all have to learn somewhere.

    Please don't discourage people from helping others, or answering questions on this forum.

    We as professionals giving help through suggestions on this forum also have to judge by what questions are asked, the level of ability the questioner has, because we have no idea...most DIYrs that have to ask about something we regard as basic sets off a alarm that leads us to believe, right or wrong, that the DIYer is heading into an area that he/she knows little or nothing about...An open electrical panel is not where a novice with no knowledge needs to be...enough experienced electricians that become complacent are injured and some die even though they are well trained. Something as simple as wearing a wedding band while working in a panel can be deadly.

    So if you find sometimes that it seems someone does not want to help it is due to caution and us knowing what can happen to someone who, in our opinion, is somewhere he has no business being and doing something he has no or limited knowledge about.

    It is a moral call each individual has to make. So don't take it personally, we have no way of knowing what your level of ability is.

    It boils down to many people knowing just enough about something to be dangerous or deadly and us trying to figure out if your one of them.
    Last edited by Cass; 11-24-2008 at 08:38 AM.

  12. #27
    DIY Junior Member Rowdy's Avatar
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    mnalep, It is my understanding that you have tested for voltage, checked your fixtures for good connections, checked continuity between neutral and ground, and then checked them all again and again.

    Your tests aren't producing results so it is time to try basic troubleshooting. Talk to your Mother and try to get as much information as possible on the problem, when the light fixture stopped working? What was going on at that time, like remodeling, putting screws or nails into the walls, installing new fixtures and as many other changes that she can think of.

    Someone said a GFI may be tripped in the circuit, with voltage present I have my doubts, but look for a tripped GFI, inside, outside, in the garage or any other place that there could be one.

    Try isolation:

    By now you know the circuit pretty well, shut the power off and go to wherever you feel is the center of that circuit and remove the fixture, tape all exposed wiring individually so that there is no chance of anyone getting hurt then turn the power back on and see if the problem exists in that half of the circuit. If there is a problem there, shut the power off and remove the fixtures one by one taping all of the bare conductors and turning the power back on.

    Sometimes testing only leads to frustration, try isolating and see if that will get you results. Good Luck.

  13. #28
    DIY Senior Member mnalep's Avatar
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    Cass, I hear what you are saying. I will take his comment in stride. Thank you.

  14. #29
    DIY Senior Member mnalep's Avatar
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    Rowdy, Thanks for your help.

    I have not yet moved the wiring from the push in's to the screw terminals. I plan to try that tonight or tomorrow.

    I like the idea of disconnecting the circuit in the middle and observing if the problem still exists on the first half of the circuit. Divide and conquer.

    BTW, There is no GFCI's anywhere in my mom's house. I examined at all the outlets when I was observing to determine all the outlets and lights on this one bad circuit.

  15. #30
    Homeowner Thatguy's Avatar
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    Quote Originally Posted by mnalep View Post
    PS: I totally don't understand the sensitivity, OHMS/Volt, and resisitance you wrote about?
    It's a bit hard to understand.

    A measuring device should not change the circuit voltage when you hook it up to read voltage. The higher the sensitivity of the meter, the less the voltage you're measuring is dropped when you hook up your meter.

    I have a DVM that has 20 MΩ input impedance, so if it's measuring 20v it only pulls 20/20MΩ = 1ľA from the circuit it's measuring. This is OK for almost all applications except vacuum tube circuits, and there aren't very many of them around anymore.

    My 1000Ω/volt meter on the 20v scale would pull 20/20kΩ = 1 mA from the circuit being measured.

    You can pull about 5A out of household circuits and only drop the voltage ~1%, except when measuring these phantom voltages.

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