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Author Topic: 5-15 multimeter leads?  (Read 8706 times)

Erik Jerde

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Re: 5-15 multimeter leads?
« Reply #10 on: October 28, 2018, 01:19:51 am »

I've thought about arranging 3 banana jacks in a 1" triangle so that a dual banana plug could easily test H-N, N-G or G-H. But that's just for my demonstrations. For actual power testing at a gig I always use a SureTest Analyzer. Takes only a few seconds to test for voltage, polarity, ground impedance, etc... Plus it does a predictive load test and calculates how much voltage drop you'll have if you draw 15 or 20 amps load on that circuit.

Can any of them test for a RPBG?  How about voltage present on any single line (not just line pairs)?
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Mac Kerr

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Re: 5-15 multimeter leads?
« Reply #11 on: October 28, 2018, 10:02:28 am »

Can any of them test for a RPBG?  How about voltage present on any single line (not just line pairs)?

How do you have voltage if you only measure one line? Voltage is the electrical potential between two points. You can only measure it between two points.

Mac
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George Friedman-Jimenez

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Re: 5-15 multimeter leads?
« Reply #12 on: October 28, 2018, 12:54:17 pm »

The trouble with flat tip probes these days is TR outlets.  Those can be a real bitch to get any kind of probe into.  If I regularly had to test TRs Id absolutely get a purpose built device like mentioned above or construct a cable that would expose the 3 conductors in a finger-safe manner.
If you only do this occasionally, you can use a non-conducting flat object that fits, like a sliver of wood, to insert in the other slot as you insert the tester in one slot. This will open up the tamper resistant internal flap. Or insert both probes at the same time and leave one in when you pull the other one out to test the ground. PITA if you don't have kids around to protect.
« Last Edit: October 28, 2018, 12:56:47 pm by George Friedman-Jimenez »
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Frank DeWitt

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Re: 5-15 multimeter leads?
« Reply #13 on: October 28, 2018, 03:58:19 pm »

But most of them are dependent on the line voltage itself for power. The Kill A Watt meter dies somewhere around 90 volts.

Well, this one will take you down to 50 Volts and it's nice to have a old quality product.  Do a eBay search for emico ac voltage tester. 
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Erik Jerde

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Re: 5-15 multimeter leads?
« Reply #14 on: October 28, 2018, 07:02:40 pm »

How do you have voltage if you only measure one line? Voltage is the electrical potential between two points. You can only measure it between two points.

Mac

Integrate a NCVT on each line.  Those indicate voltage on a single isolated line.  Just gotta think creatively here Mac.
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Stephen Swaffer

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Re: 5-15 multimeter leads?
« Reply #15 on: October 28, 2018, 10:04:16 pm »

NCVT's often give false positives-which is to say they fail safe.  JR put a lot of effort into designing a plug in tester that would reliably detect RPBG. Do a search to read the long thread on the subject.  I had a friend refuse to use a receptacle at a venue that I am fairly certain was fine-but it lit up his inexpensive NCVT and better to be on the safe side. I wasn't setting up soound so wasn't prepared myself to take an extension cord and a DMM and do a definitive test-I will as soon as I get the chance.

TR receptacles will probably become much more common-virtualy any public space has the for children to be around at different times.  Even a carefully chosen 5-15 replacement plug can make a handy tool to bring the connections out in finger safe way-faster, easier and less likely to damage than defeating the TR mechanism.
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Steve Swaffer

Mark Cadwallader

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Re: 5-15 multimeter leads?
« Reply #16 on: October 29, 2018, 12:27:59 am »


TR receptacles will probably become much more common-virtualy any public space has the for children to be around at different times.  Even a carefully chosen 5-15 replacement plug can make a handy tool to bring the connections out in finger safe way-faster, easier and less likely to damage than defeating the TR mechanism.

If you just need to safely get around TR recepticals, wouldn't a 6"/150mm long "extension cord" do the trick for test purposes?
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Mike Sokol

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Re: 5-15 multimeter leads?
« Reply #17 on: October 29, 2018, 07:52:26 am »

Quote from: Erik Jerde link=topic=169088.msg1559288#msg155928date=1540703991
Can any of them test for a RPBG?  How about voltage present on any single line (not just line pairs)?

No, you can't test for an RPBG (Reverse Polarity Bootleg Ground) by measuring between H-N, H-G and G-H. You need to measure voltage between the Ground and earth-ground. So you can use a NCVT to test for elevated EGC (the ground wire voltage), or by putting one of the meter probes on a ground-rod, the metal box of the service panel, or the ground wire of another branch circuit that you KNOW is wired properly.
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Frank Koenig

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Re: 5-15 multimeter leads?
« Reply #18 on: October 29, 2018, 10:45:42 am »

It sounds like what we need is a simple molded piece with 5-15 prongs on one end and well-labeled and color coded banana jacks on the other. Actually, a set of these to fit L14-20, L14-30, L21-whatever would be a nice kit. Just in time for Christmas. With that you could perform whatever tests you want with meters, NCVTs, etc. It could be combined with a 3 light tester. -F
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Jonathan Johnson

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Re: 5-15 multimeter leads?
« Reply #19 on: October 29, 2018, 11:43:38 am »

Seems to me a "cheater plug" should work just fine for bypassing the shutters of tamper resistant receptacles.
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Re: 5-15 multimeter leads?
« Reply #19 on: October 29, 2018, 11:43:38 am »


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