Backfeed or something????

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I had some MC like that - Oh was that a good catch in rough! Had the was closed it would've been disaster.... Liner missing and one conductor partially insulated....

On the OP - I dislike the "Voltage isn't really there" ideas.... The voltage is there, and measurable - it however it may or may not usable under any type of load. Know your equipment and it's characteristics IMO. Wiggy or DMM it's a personal choice...
 
e57 said:
I had some MC like that - Oh was that a good catch in rough! Had the was closed it would've been disaster.... Liner missing and one conductor partially insulated....

On the OP - I dislike the "Voltage isn't really there" ideas.... The voltage is there, and measurable - it however it may or may not usable under any type of load. Know your equipment and it's characteristics IMO. Wiggy or DMM it's a personal choice...
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I would say if you load it with any sort of load, and then measure the voltage drop on that load, you are most likely to read a big fat zero, regardless of the quality of your meter. Assuming correct wiring, and no damage in wire insulations, it seems to me that the voltage is induced, and of such high source impedence that it will produce no current, even under short circuit. e/m
 
Energy-Miser said:
I would say if you load it with any sort of load, and then measure the voltage drop on that load, you are most likely to read a big fat zero, regardless of the quality of your meter.
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Exactly! Then again it might not.... I have seen an induced voltage good enough to hold current - then again it was from a better part of a mile long... I have also measured odd voltages through a load and gotten simular readings that would not be apparent on a wiggy either. A wiggy used on certain types of devices and components is useless possibly damaging - like using a sledge hammer on a finish nail. It matters not what the assumed 'quality' of the meter is - a DMM and a Solonoid meter operate on two different concepts, and therefore different tools altogether IMO. Knowing how to interpet what they tell you is the key.
 
Many years ago I ran a service call at a church. Problem was a countertop receptacle in the church kitchen. They told me the mixer wouldn't work when plugged into that outlet. I take my trusty Simpson analog meter (which is a high impedance meter) and I read 120 volts from the hot slot to the neutral slot. Hmmm.... receptacle and voltage is good. The problem must be the mixer. So I plug the mixer into a different receptacle on another wall. It works.

Hmmmm....

I go and get a drill motor from the truck and plug it into the receptacle in question. Doesn't run. Plug the drill into the other receptacle on other wall. It runs.

Obviously the outlet in question is bad. I pull it out of the box and discover that the hot-side wire termination screw is badly corroded and and obviously has a fairly high resistance in series with the receptacle. Replace the receptacle, everything is back to working.

So the mixer and the drill motor indicated there was no voltage at the outlet. But the Simpson said there was full voltage there. Understand that I was using the mixer and the drill motor as "low impedance" voltage testers. A wiggie would have indicated the same thing as the mixer.

Here is the theory: The resistance of the mixer was way lower than the bad termination. The resistance of the Simpson was way higher than the bad termination. In a series circuit, the largest resistance will drop the most voltage.

When the Simpson was in series with the bad termination, the large majority of the voltage drop would be seen across the meter and it read near full voltage. When the mixer was in series with the bad termination, most of the voltage drop occurred across the bad termination. There wasn't enough voltage across the mixer to make it run.

Yes, both meters were right under the conditions. But which meter was most useful to the electrician in the field on that day?

Both meters have their place. But for ordinary residential and commercial troubleshooting, if I had to choose only one, I'd definitely consider the wiggie. But if I don't have to choose, I want to have both.
 
crossman said:
Many years ago I ran a service call at a church. ... Yes, both meters were right under the conditions. But which meter was most useful to the electrician in the field on that day?

Both meters have their place. But for ordinary residential and commercial troubleshooting, if I had to choose only one, I'd definitely consider the wiggie. But if I don't have to choose, I want to have both.
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Excellent example. Same happens with a battery that is old and has a high internal resistance. Measured with your high impedance voltmeter, it will register its rated voltage. Load it and measure its voltage under load and you will read a fraction of the rated voltage. The good old voltage divider principle has put most of the voltage on the internal resistor and very little on the load. That's why I always say "test it under load". I even say that about my kids. When my wife says they has been very good lately, I always tell her, well test them under load ! I think she knows what I mean by that :)
 
crossman said:
Yes, both meters were right under the conditions. But which meter was most useful to the electrician in the field on that day?

Both meters have their place. But for ordinary residential and commercial troubleshooting, if I had to choose only one, I'd definitely consider the wiggie. But if I don't have to choose, I want to have both.
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Yes - excellent example. But I think the old bake-lite box was the most usefull. (I love those old Simpsons) It told you voltage WAS THERE, but a Wiggy may have told you there was not - you may have gone a wild goose chase thinking there was an open or tripped breaker somewhere. Or worse you may have opened the box thinking it dead, only to find that it was live - your body may have somewhere in between the impedance of both types of meters... :rolleyes: Seen that happen in varying degrees from a little tingle to "WHOA BABY!" I have also seen instances where you could operate say a toaster, but add a night-lite and all goes dim.

That said I own several DMM's, a few different inductive testers just for quick checks, and a Wiggy that I haven't touched in years.
 
melanconelectric said:
Recently remodeled an older home and installed 1500W HVL in the mast bath, one of those with heat-vent-light-night light. At trim out, i got a 2 gang switch box with one 12/2 HR coming in, dedicated. Got two 12/3 coming out ( 4 switch leg returns). In one 12/3 when I energize the blk with 120V, I get 41V on the red. No staples in the cable, NOTHING is terminated in the fixt housing, not even neutrals. And only that neutral for that cable is tied in with the incoming neut. When de-energized, no continuity-no resistence from blk to red. 12 years and I never seen this!
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Why were you "testing" the wires. Did the unit not work?

Get rid of the multimeter and use a wiggy. I think the only time I use a multi meter is for checking continuity in fuses or something or for very specific voltage or frequency readings.

I have been very suprised to see some very seasoned electricians checking a fuse or breaker to ground in a panel to see if the OCP is good.
 
e57 said:
Yes - excellent example. But I think the old bake-lite box was the most usefull. (I love those old Simpsons) It told you voltage WAS THERE, but a Wiggy may have told you there was not - you may have gone a wild goose chase thinking there was an open or tripped breaker somewhere. Or worse you may have opened the box thinking it dead, only to find that it was live -
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Excellent thoughts! I did not look at it from that angle. There is no doubt that simply using the wiggie and then assuming the circuit was off could have gotten me hurt. I am curently rethinking my views on meters due to your commentary. And I am with you.... my old Simpson in the bake-lite box holds a warm spot in my heart.

Edit: added photo
 
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jrannis said:
I have been very suprised to see some very seasoned electricians checking a fuse or breaker to ground in a panel to see if the OCP is good.
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Seems logical to me. I have been in countless situations where a client is telling me that "It's CB #7 - we already reset it", only to find that the CB is not resetting, but more often that it wasn't #7 at all, but #9, the panel is mis-marked, and breaker handle 'appears' to be in the on position. Click click done - here's your bill - bye... :grin: (Yes I re-mark the panel before I go)

Crossman - I wasn't looking to convert you - but I think you understand my point.

I believe Fluke makes a meter for those of us who want both. And although this literature uses the dreaded words 'ghost voltage' (which I have avoided using here because the concept is miss-leading and should not exist IMO) it does explain some of what I was reffering to about the purposes of both. And without too much additional cost - an adaptor for ~$80
 
I have had false voltage reading with a Fluke AND a Wiggy.

When in doubt, stick your fingers on it and/or give it the flash test.
 
e57 said:
Crossman - I wasn't looking to convert you - but I think you understand my point.
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The great thing about this forum is that it makes me think. You pointed out something I didn't consider. Now, being armed with the new understanding, I am more competent. Thank you! Being aware of the different situations which confront us as electricians is half the battle.

e57 said:
I believe Fluke makes a meter for those of us who want both.
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Interesting product. I kinda want one now.
 
220/221 said:
I have had false voltage reading with a Fluke AND a Wiggy.

When in doubt, stick your fingers on it and/or give it the flash test.
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Not sure we should advocte the 'lick and stick' method... Or the 'turn head away and stick' method...
 
Oops!

Oops!

I just installed one of those HLV a week ago. The blower motor will run when the heat strips are lit. I think what you are seeing isn't bad wiring but the blower motor.
The current needs were 1500 w and the j-box on the side of the device is better suited for 14 gauge wire.
I would unplug the devices up in the HLV and check for opens there. If I was still getting my 41 volts, look in the crammed up j box on the device, recheck the wiring diagram, and make sure I have my switch wired right.
The other thing is make sure you have a good battery in your meter. Normally it shows as a high voltage spike when the battery gets week though.

Megger... sheesh.
 
The Original Poster said that none of the wires were connected to the fixture yet.... was probably just checking which wires came from which switch by checking voltage from the wires to ground and then flipping the switches on and off. Discovered the 41 volts in the process.
 
crossman said:
The Original Poster said that none of the wires were connected to the fixture yet.... was probably just checking which wires came from which switch by checking voltage from the wires to ground and then flipping the switches on and off. Discovered the 41 volts in the process.
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I don't think you would need the wires to be terminated to get induced voltage. Do you????

Anyway this is another example of a question being asked and no response from the op.
 
Dennis Alwon said:
I don't think you would need the wires to be terminated to get induced voltage. Do you????
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Oh my, Dennis!

My post was a response to GUNNING saying the following:

The blower motor will run when the heat strips are lit. I think what you are seeing isn't bad wiring but the blower motor.

I was simply letting him know that the motor and heat was not involved in the 41 volts.

And dang, I get a quadruple question mark "Do you" out of it?:mad:
 
crossman said:
Oh my, Dennis!

My post was a response to GUNNING saying the following:

The blower motor will run when the heat strips are lit. I think what you are seeing isn't bad wiring but the blower motor.

I was simply letting him know that the motor and heat was not involved in the 41 volts.

And dang, I get a quadruple question mark "Do you" out of it?:mad:
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I was actually asking the question because I wasn't certain. I didn't think you needed a load to have induced voltage, but I wasn't certain. I also always use more than one ?. It is a bad habit. Sorry, if you read my other posts where there are questions I usually have 3 or 4. I am not sure why I do it but I have done it for a long time.
 
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