Dang!! Thanks man. I'm a Journeyman electrician that typically does commercial. I once got a job to a very old home where the handyman refused to install a fan because with the breaker off we still read 30V on the hot. I was miffed to. I understood that it was "ghost voltage" and not hazardous however I just couldn't explain it properly. Now I fully understand. I have since purchased a Loz meter. Thank you Sir.
Oh that’s what that mode is for. That would have been handy last week. Had line voltage on a wire in a conduit and wasn’t sure if it was energized or just capacitively coupled with another wire
Fantastic explanation of all of this! I never heard of a meter with the LoZ functions or thought there was a good way to test for a bad connection like that.
Steve, thanks for this. Always good content. One question… towards the end of the video you mention that, when we apply a DMM to a circuit we are creating a series circuit. Are we not actually in parallel? If we were in series & measuring with the VAC function would we not be dropping all of our voltage across the DMM and therefore interrupting our circuit of interest altogether? Isn’t 5mOhm a functional open?
Great question. When measuring a voltage, your DMM is in parallel with the voltage source or whatever you are measuring across, but is in effectively in series with the internal resistance of the voltage source. Yes when you are measuring a voltage source, since you are in series with what is ideally an extremely low internal resistance of the source, the voltage divider rule dictates that 99.99% (depending on that internal resistance) of the voltage appears across the meter. So yes,, for all practical purposes, it is open, but highlighting the small effect that the 5M ohm resistance does have on the circuit illustrates the relative difference in how it, vs. the 3K ohm LoZ affects that circuit, and why it is used.
Lots of questions about why LoZ was in DC mode in some parts of the video. This is normal when the voltage is zero. This meter auto-selects AC or DC. If the voltage is zero, it starts off in DC and switches to AC when it detects AC voltage.
In the section “compromised voltage”, I could either test the outlet as is in LowZ or test the outlet regular but under a load to see the voltage is not reading 120 as it should?
If I understand this LoZ is basically introducing a load into an otherwise open circuit. This is what we do in automotive and other machinery DC low voltage circuits usually with a light bulb of known load to check the integrity of the circuit. Voltage testing of a loaded circuit I guess is what it might be called. Will this LoZ work on DC voltage? It seems like it would be a big help if it does.
Yes, LoZ mode works with DC voltage on certain multimeters depending on their specs. They basically just effectively introduce the same approximate 3K resistance across the test leads - providing much greater loading than the typical 5 megaohm input resistance.
is it ghost voltage that makes led lights glow when they are turned off? current leakage effect is why downed power lines are so dangerous especially in wet conditions such as after a thunderstorm. your house gets 220 witch is split into 2 110 sources but a power line can carry 15000 volts at several thousand amps depending on how many houses are fed from the transformer. i think that leakage current is what gfi breakers, outlets and plugs is detecting when there is a fault. we see compromised voltage sources in cars where the crust has formed on one of the terminals. i imagine a scenario where something is wrong with the car that caused the crust to form on the battery and someone who does not know enough about their car may try to jump it with one of them cheap even disposable jump starters that can dump as much as 24 volts into the battery to charge first may fry the car computer (ecu, ecm or brain boxes ) and total their car. this works because the jump boxes are designed to be used to charge the battery enough to get the car started but the crust causes enough resistance that instead of the battery getting the charge the cars electrical system gets the higher voltage and can destroy the electronics including the cars computers. replacing the electronics can get very expensive possibly costing more than the car thereby you can have a brand new car with a defective alternator that is overcharging and outgassing the battery and a cheap jump starter that connects to the cigarette lighter port will dump up to 24 volts into the car.
There was a circuit from 2008 on a mower engine that purposely allowed crossover leakage induction volts from a 5 turn wire onto an adjacent 7 turn wire, WITHOUT core, so as the in series volts is increased from 12 to over 100 volts. Was this brilliant, or just a cheap method of increasing a lower voltage. See photo of S1R9A9M9 triple wires assembly electromagnet on internet images. The LOWER only section of 13 turns had steel core. This was in reference to HIS (2) UA-cam videos that can still be seen. . (On old, worn out ignition cables, they spark across in the dark at night when you lift the hood on bad ignition cables.) He put this to use for his project in 2008. Please write back so I know you received my message. Is this type called capacitive voltage induction? My first test on this showed a neon bulb glowing with at least 90v, FROM ONLY THE 7 TURNS WIRING, not electrically connected to 5 turns.
Great tutorial on LoZ, it's much clearer to me now.
Glad it helped.
Dang!! Thanks man. I'm a Journeyman electrician that typically does commercial. I once got a job to a very old home where the handyman refused to install a fan because with the breaker off we still read 30V on the hot. I was miffed to. I understood that it was "ghost voltage" and not hazardous however I just couldn't explain it properly. Now I fully understand. I have since purchased a Loz meter. Thank you Sir.
Thanks for the feedback! Feel free to share the video.
👍Thank You! Very well done. Your demo/presentation made this easy to understand.
Thank you for the nice words. Feel free to share the video.
Nice explanation of ghost voltages
This is the best explanation of the loZ function of multimeters and ghost voltage I've ever seen! And more. Thank you very much!
Thank you for the feedback. Feel free to share the video.
You made that so easy to understand. I look forward to viewing the rest of your videos thanks
Thanks! Feel free to share.
This was a very helpful demo, thankyou for taking the time to explain it all so clearly
Glad it was helpful!
Great video, this helped me a lot as an Apprentice still trying to hone in on the theory side of electrical.
Thanks !
You're welcome!
Outstanding video!
Thanks!
Oh that’s what that mode is for. That would have been handy last week. Had line voltage on a wire in a conduit and wasn’t sure if it was energized or just capacitively coupled with another wire
Damn now I kind of want to buy a fluke 116 but I dont really need it for most of my work. Great explanation!
Thank you.
Fluke 115 also has this function. You hold the Range button down when turning on.
Thanks for great explanation!
You're welcome!
Fantastic explanation of all of this! I never heard of a meter with the LoZ functions or thought there was a good way to test for a bad connection like that.
Thank you for the kind words.
New appliance tech here. Thanks for the relevant explainer. I'll be on the lookout for weird shit now. 😂
Very well explained!!
Glad to help.
Very Nice!
Thanks!
Steve, thanks for this. Always good content.
One question… towards the end of the video you mention that, when we apply a DMM to a circuit we are creating a series circuit. Are we not actually in parallel?
If we were in series & measuring with the VAC function would we not be dropping all of our voltage across the DMM and therefore interrupting our circuit of interest altogether? Isn’t 5mOhm a functional open?
Great question. When measuring a voltage, your DMM is in parallel with the voltage source or whatever you are measuring across, but is in effectively in series with the internal resistance of the voltage source.
Yes when you are measuring a voltage source, since you are in series with what is ideally an extremely low internal resistance of the source, the voltage divider rule dictates that 99.99% (depending on that internal resistance) of the voltage appears across the meter. So yes,, for all practical purposes, it is open, but highlighting the small effect that the 5M ohm resistance does have on the circuit illustrates the relative difference in how it, vs. the 3K ohm LoZ affects that circuit, and why it is used.
Lots of questions about why LoZ was in DC mode in some parts of the video. This is normal when the voltage is zero. This meter auto-selects AC or DC. If the voltage is zero, it starts off in DC and switches to AC when it detects AC voltage.
In the section “compromised voltage”, I could either test the outlet as is in LowZ or test the outlet regular but under a load to see the voltage is not reading 120 as it should?
Yes. Either method places a relative low impedance across the source.
If I understand this LoZ is basically introducing a load into an otherwise open circuit. This is what we do in automotive and other machinery DC low voltage circuits usually with a light bulb of known load to check the integrity of the circuit. Voltage testing of a loaded circuit I guess is what it might be called. Will this LoZ work on DC voltage? It seems like it would be a big help if it does.
Yes, LoZ mode works with DC voltage on certain multimeters depending on their specs. They basically just effectively introduce the same approximate 3K resistance across the test leads - providing much greater loading than the typical 5 megaohm input resistance.
👍👍
at 2:00 I see 0 VDC reading.
Is the DC scale intentional ???
It auto selects AC or DC.
AT 8:12 YOU SAY "WE HAVE A BAD OUTLET" - IS IT THAT ONLY THE CONNECTION IS BAD AND THE OUTLET IS GOOD ?
is it ghost voltage that makes led lights glow when they are turned off?
current leakage effect is why downed power lines are so dangerous especially in wet conditions such as after a thunderstorm.
your house gets 220 witch is split into 2 110 sources but a power line can carry 15000 volts at several thousand amps depending on how many houses are fed from the transformer.
i think that leakage current is what gfi breakers, outlets and plugs is detecting when there is a fault.
we see compromised voltage sources in cars where the crust has formed on one of the terminals.
i imagine a scenario where something is wrong with the car that caused the crust to form on the battery and someone who does not know enough about their car may try to jump it with one of them cheap even disposable jump starters that can dump as much as 24 volts into the battery to charge first may fry the car computer (ecu, ecm or brain boxes ) and total their car.
this works because the jump boxes are designed to be used to charge the battery enough to get the car started but the crust causes enough resistance that instead of the battery getting the charge the cars electrical system gets the higher voltage and can destroy the electronics including the cars computers.
replacing the electronics can get very expensive possibly costing more than the car thereby you can have a brand new car with a defective alternator that is overcharging and outgassing the battery and a cheap jump starter that connects to the cigarette lighter port will dump up to 24 volts into the car.
No. That is not caused by a ghost voltage.
There was a circuit from 2008 on a mower engine that purposely allowed crossover leakage induction volts from a 5 turn wire onto an adjacent 7 turn wire, WITHOUT core, so as the in series volts is increased from 12 to over 100 volts. Was this brilliant, or just a cheap method of increasing a lower voltage. See photo of S1R9A9M9 triple wires assembly electromagnet on internet images. The LOWER only section of 13 turns had steel core. This was in reference to HIS (2) UA-cam videos that can still be seen. . (On old, worn out ignition cables, they spark across in the dark at night when you lift the hood on bad ignition cables.) He put this to use for his project in 2008. Please write back so I know you received my message. Is this type called capacitive voltage induction? My first test on this showed a neon bulb glowing with at least 90v, FROM ONLY THE 7 TURNS WIRING, not electrically connected to 5 turns.