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Author Topic: 2-phase hum?  (Read 6604 times)

Chris Hindle

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Re: 2-phase hum?
« Reply #20 on: February 12, 2016, 08:22:18 am »

Not to throw gas on the fire, but what should we call the two sides of the distro, if not phase?
I call it a Leg. Red Leg, or Black Leg.
Chris.
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Mike Sokol

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Re: 2-phase hum?
« Reply #21 on: February 12, 2016, 08:24:11 am »

My first thought is that everyone running a small California plug distro would immediately have such a problem.  But the neutral to both legs as well as the ground to both legs is at the same potential in the distro since each is on a single wire.  Any neutral to ground current will be common to both legs.  Using only one side of the distro (phase, if you want to misuse that term) kind of cripples why you have it in the first place.

Since we understand that ground loop hum in a system is typically caused by ground loop currents in the shields, we can predict the types of situations that can cause these currents to form in the first place. And as I've demonstrated many times, it's pretty simple to measure these shield currents with a clamp-on ammeter. 
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Chris Hindle

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Re: 2-phase hum?
« Reply #22 on: February 12, 2016, 08:26:52 am »

So what do we call swapped Hot and Neutral wires?

"Potentially Lethal"

Chris.
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Stephen Swaffer

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Re: 2-phase hum?
« Reply #23 on: February 12, 2016, 06:36:21 pm »

But I see this term mis-used in the RV industry all the time when swapped Hot and Neutral wires are referred to as "reverse polarity". Of course, AC power in the US swaps polarity 120 times a second (60 Hz). Sadly, many so called RV "experts" think it causes an RV hot-skin voltage, which isn't true.

So what do we call swapped Hot and Neutral wires?

Well, if you follow NEC usage you call it reversed polarity. 410.50 talks about "polarization of lumiaires"

"200.11 Polarity of Connections  No grounded conductor shall be attached to any terminal or lead so as to reverse the designated polarity."

Who opened this can o'worms?
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John Roberts {JR}

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Re: 2-phase hum?
« Reply #24 on: February 12, 2016, 07:30:22 pm »

Well, if you follow NEC usage you call it reversed polarity. 410.50 talks about "polarization of lumiaires"

"200.11 Polarity of Connections  No grounded conductor shall be attached to any terminal or lead so as to reverse the designated polarity."

Who opened this can o'worms?
I hate the rather confusing use of english words to vaguely suggest some real word. I think (hope?) "grounded" conductor means neutral.  The real problem is where the "ungrounded" (hot, line, whatever) conductor gets connected.

Neutral (grounded) should be low voltage so relatively harmless. >:(

JR
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Stephen Swaffer

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Re: 2-phase hum?
« Reply #25 on: February 12, 2016, 07:42:18 pm »

True, but assuming you have the same number of wires as terminals and attach one wire to each terminal, if the grounded conductor is on the wrong terminal, then it impossible to put the ungrounded conductor on the correct terminal.
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Steve Swaffer

Mike Sokol

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Re: 2-phase hum?
« Reply #26 on: February 12, 2016, 08:39:47 pm »

Who opened this can o'worms?

Ummmmmmm...... :)
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David Buckley

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Re: 2-phase hum?
« Reply #27 on: February 12, 2016, 09:17:12 pm »

Ummmmmmm...... :)

Typical.  Misuse of a silent "h".
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Lyle Williams

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Re: 2-phase hum?
« Reply #28 on: February 12, 2016, 10:57:29 pm »

Which brings us back around to equipment design... The more bits we try to send down network cables the easier it is to confuse it. I like the concept of running equipment off the same power drop because they all see the exact same ground corruption, but there is no theory to support this, just practice.

JR

People get bent out of shape insisting on the highest quality source of power.  They must have the most pristine 115v, or 12v, or whatever.

But voltage is all relative.  You need a fabulous source of "0v" to begin with.

Selling "zero volt supplies" does sound like a scam, doesn't it?

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Mike Sokol

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Re: 2-phase hum?
« Reply #29 on: February 12, 2016, 11:53:33 pm »

Typical.  Misuse of a silent "h".

hmmmmmmmmmmmm.....?  :)
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Mike Sokol
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Re: 2-phase hum?
« Reply #29 on: February 12, 2016, 11:53:33 pm »


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