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Author Topic: Hot and Neutral swapped.  (Read 19512 times)

Stephen Swaffer

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Re: Hot and Neutral swapped.
« Reply #30 on: September 19, 2014, 02:34:29 PM »

As long as I or mine is not part of their data... 
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Steve Swaffer

Frank DeWitt

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Re: Hot and Neutral swapped.
« Reply #31 on: September 19, 2014, 04:30:56 PM »

Very early homes in the US were wired with out any chance of of a hot neutral swap because there was no reference to ground at all.  Some city fire codes did not allow a reference to ground and if one was found it was a fault and had to be found and removed. 

Later homes had no problem because there were no outlets.  Electricity was installed for lighting.  Neither Edison nor anyone else had anticipated portable appliances.  When they did appear they were screwed into light sockets.  The first outlets were Edison sockets  mounted on the wall with a little brass door over them.

These early Edison screw based wall outlets and plugs are still around and show up on Ebay continuously.

A lot more info here.
http://www.rexophone.com/?p=1175
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Not to Code

Stephen Swaffer

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Re: Hot and Neutral swapped.
« Reply #32 on: September 19, 2014, 07:23:15 PM »

Upon further reflection the bin situation poses quite a conundrum-and while my question was indeed rhetorical or sarcastic, it does illustrate a challenging situation with electrical installations.

The conundum is this-there are 2 two wire recept and 1 three wire.  I am being asked to hook up a motor-my electrician brain tells me to use the safest option and gain the peace of mind from a copper EGC.  However, the motor I am wiring is solidly bolted to an auger that is solidly bolted to the bin which is the best grounding electrode in the area.  The most likely use for the 2 wire recepts would be to power portable augers-leading to the potential for a short to energize the frame, which will likely be located close to the bin-just begging for a meat puppet to grab both the grounded bin and the energized auger.

Ordinances and practice generally allow the grandfathering of existing wiring.  A necessity since virtually any install over 3 years old will likely not be compliant with current code.  Our state inpsectors inspect new installs, but have the authority to inisist that "serious" safety violations be addressed.  I as the "qualified electrician" am often placed on the spot- "is this safe" "what do we do to make this safe"?  I have a vested interest in the answer since I will profit from an upgrade-but I am also potentially liable if the upgrade is not suffcient-and I want to be ethical.

So what say ye?  When should an install be considered dangerous enough to mandate an upgrade?  In the above example-2 wire/ 3 wire-maybe weatherproof in use cover perhaps GFCI?  In a home-k & T ok?  Fuses? Two wire recptacles? If the only appliances in a living room are two wire (typical anymore) why do we need 3 wire?  What if non TR recptacles-they don't meet current code either?

While incorrect wiring (reversed hot/neutral) is never acceptable-what really should be fixed is often a difficult question! 
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Steve Swaffer

Jonathan Johnson

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Re: Hot and Neutral swapped.
« Reply #33 on: September 19, 2014, 08:08:47 PM »

While incorrect wiring (reversed hot/neutral) is never acceptable-what really should be fixed is often a difficult question!

The thing to remember about codes is that they provide for a reasonable level safety in *most* situations and standard methods of installation. I'm sure we are all aware of perfectly safe situations that are in violation of code, and potentially hazardous situations that fit the letter of the code. Occasionally we may even come across situations that if the install is done to meet code it will actually pose a greater danger; there is no way to make it safe without violating the code. It's all a judgment call, and one of the reasons that exceptions exist in the code.

In the case of the grain bin, the bin certainly may prove to be a superior grounding electrode. But if the grain bin is not bonded to the electrical system's EGC and GEC, then there will be a very real possibility of a voltage potential between the system EGC and the grain bin. In the event of a fault in the motor, the grain bin could be energized and someone coming between the bin and another properly grounded device could receive an electrical shock. If the motor has no EGC, then the grain bin it is bolted to should be bonded to the system EGC.
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Kevin Maxwell

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Re: Hot and Neutral swapped.
« Reply #34 on: September 20, 2014, 05:13:58 PM »

The more I think about this the less sense it makes. All I did in an attempt to fix this was to swap the 2 wires in the duplex I put the Black wire where it was supposed to have been put and the White wire where it was supposed to have been put.

This was after metering them to be sure the Black was hot and that the White was the neutral. With nothing plugged into the duplex I turned the breaker back on and it immediately tripped the breaker. I see nothing that should have done that. The 2 wires were not carrying any load at all. Even anything down stream or up stream of this duplex should have made no difference with what I did. Unless the duplex was shorted internally, and that doesn’t make any sense either because the short would have had to happen as I was rewiring it.

I had wrapped electrical tape around the duplex to prevent the connections from touching the box. When it tripped and I took everything apart there where no burn marks on the tape. The white wire did have a scorch mark on it. The only thing that I can think of is maybe I didn’t look closely enough to see if one of those jumper wires was cracked and I didn’t see it. I put the wires that I removed by the mixer. I hope they are still there and I will have to look at them very closely, probably on Monday.
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Stephen Swaffer

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Re: Hot and Neutral swapped.
« Reply #35 on: September 20, 2014, 05:22:38 PM »

I wasn' trying to hijack the thread with the bin issue-it is what it is and I will get a reasonably safe install and go on (most of these ag systems are a nightmare finding an egc or gec is like winning the lottery and the biggest mystery of all is why more farmers are not electrocuted every fall!-I treat everything as potentially energized)  My point is/was that it is not always black and white on modifications to existing installations and my recommendations sometimes depend on anticipated uses-so if I or the owner does not anticipate video/lighting/entertainment uses the wiring may not be what you need(ground loops, etc-and it might not necessarily be the fault of a wiring hack job-hence the importance of testing so you know what you have to work with.
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Steve Swaffer

Stephen Swaffer

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Re: Hot and Neutral swapped.
« Reply #36 on: September 20, 2014, 05:31:04 PM »


I had wrapped electrical tape around the duplex to prevent the connections from touching the box. When it tripped and I took everything apart there where no burn marks on the tape. The white wire did have a scorch mark on it. The only thing that I can think of is maybe I didn’t look closely enough to see if one of those jumper wires was cracked and I didn’t see it. I put the wires that I removed by the mixer. I hope they are still there and I will have to look at them very closely, probably on Monday.

What was your reference point for measuring hot vs neutral?  The only way the white wire could have a scorch mark-IF it is indeed neutral-would be to touch the black wire/hot screws on the receptacle.  If it is indeed neutral, nothing should happen if it touched the box (unless the box is not really grounded-but perhaps energized through conduit from another fault).  A NCVT is the most reliable way to ID a hot wire-and an essential tool for troubleshooting this problem.  Finding white wires that are actually hot is unfortunately fairly common-especially in older buildings since they often did not have a "neutral" per se and so all the wires were black-unless someone takes the time and care to tie in properly you have a 50-50 chance of getting it right.
 
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Steve Swaffer

Kevin Maxwell

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Re: Hot and Neutral swapped.
« Reply #37 on: September 21, 2014, 09:28:24 AM »

What was your reference point for measuring hot vs neutral?  The only way the white wire could have a scorch mark-IF it is indeed neutral-would be to touch the black wire/hot screws on the receptacle.  If it is indeed neutral, nothing should happen if it touched the box (unless the box is not really grounded-but perhaps energized through conduit from another fault).  A NCVT is the most reliable way to ID a hot wire-and an essential tool for troubleshooting this problem.  Finding white wires that are actually hot is unfortunately fairly common-especially in older buildings since they often did not have a "neutral" per se and so all the wires were black-unless someone takes the time and care to tie in properly you have a 50-50 chance of getting it right.

My wording about the scorch mark on the White wire was very bad. I think I only saw a scorch mark because it is white and showed up on the light color, it may have been the black wire that shorted and I could only see the mark on the white. BTW the black wire was wire nut-ed to a red wire in the outlet box. I don’t remember the color of the other wire right now.

I am supposed to do some other sound work in there Monday (tomorrow) and if the electrician hasn’t been there to fix it yet I will take a closer look then. My reference was the outlet box for ground. Since I don’t have a NCVT, I assume that is a Non-Contact Voltage Tester. If I temporarily run a lead over to the breaker panel (it is about 30feet away) is that an acceptable reference for ground?

Thank you for your help.

A TLA or ETLA is handy when repeating the same thing over and over but I feel it should be spelled out at least once in the post. TLA = Three Letter Acronyms – ETLA = Extended Three Letter Acronyms. ;D
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John Roberts {JR}

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Re: Hot and Neutral swapped.
« Reply #38 on: September 21, 2014, 10:16:22 AM »

Even w/o a NCVT you can often get a reading from a high impedance VOM on Voltage scale. Just grab the ground lead with your fingers, and probe with the hot lead of the VOM. With my cheap rat shack VOM I get enough of a reading to tell hot from not hot.

If the only thing you changed was the polarity of the connection to the outlet that does not explain tripping the breaker which suggests a short.

Good luck and be careful probing hot leads.

JR
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Stephen Swaffer

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Re: Hot and Neutral swapped.
« Reply #39 on: September 21, 2014, 04:12:57 PM »

The breaker panel should be-but possibly may not be a better reference.

What is the wiring method to the receptacle?  Romex? Metal conduit? PVC conduit?  Non-metallic methods in general should not be used in a "place of assembly"-but hot and neutral should not be swapped, either.

Using the receptacle box for a reference assumes that it is grounded (it should be!).  Obviously,that requires a metallic path back to the breaker box-if there is no green or bare EGC (equipment grounding conductor) then that relies on metal conduit.  However, even with metal conduit we must assume that there are no breaks-loose couplings etc.  We also must assume that the breaker box itself is grounded-either through an EGC with the feeder to it, or in the case of a main service panel through a box bonding screw-and it is not too uncommon to find those missing-especially in locations wired by people/volunteers that make mistakes like reversing hot and neutrals.  These are all basic things an electrician can verify-and honestly things I usually assume to be correct-until it appears that 2+2 is not adding up to 4, so then I go back to square one and start double checking everything.  Things like a box bonding screw are a 2 second check-and if you are watching me, you may not even realize I did so, but it is all part of understanding what should be happening.

JRs method works well as does a NCVT.
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Steve Swaffer

ProSoundWeb Community

Re: Hot and Neutral swapped.
« Reply #39 on: September 21, 2014, 04:12:57 PM »


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