# Switched neutrals



## Ricky&Julian (May 10, 2009)

I have been out of the residential remodel/repair market for awhile now as I have focused mainly on light commercial work. I ran into an old 1930 or 1940 knob and tube situation where they switched the neutral to the light fixture. The HO tried to repair the fixture and of course got a shock because the box was grounded and with the switch off the fixture was still hot. Was this common back then?


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## Tinstaafl (Jan 6, 2008)

Nope. Sounds like somewhere through the years, somebody worked on the wiring who shouldn't have.


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## Magnettica (Dec 19, 2006)

Actually, switching the neutral is very common in older homes with Knob & Tube. I'm talking old homes like those built before 1930-40. Your neutral is likely not a neutral but an insulated conductor identified as a grounded conductor but acting as an ungrounded conductor.


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## joelv1967 (Apr 10, 2009)

Tinstaafl said:


> Nope. Sounds like somewhere through the years, somebody worked on the wiring who shouldn't have.


 
Not true. It was very common. As a matter of fact, there is a term for it....come on you old farts....I can't remember....help me out here. I think it's a philadelphia circuit. Or is that just limited to switching the neutrals on a 3-way instead of a line/load (standard configuration). I've never seen it myself, but have heard of it.


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## Magnettica (Dec 19, 2006)

joelv1967 said:


> Not true. It was very common. As a matter of fact, there is a term for it....come on you old farts....I can't remember....help me out here. I think it's a philadelphia circuit. Or is that just limited to switching the neutrals on a 3-way instead of a line/load (standard configuration). I've never seen it myself, but have heard of it.


That's the ol' Carter System 3-way circuit. That's been discussed here before numerous times. Not sure I've ever heard of a Philadelphia Circuit though..


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## Tinstaafl (Jan 6, 2008)

I sit corrected. I've never seen that in K&T, but admittedly my experience with it is limited.


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## woodchuck2 (Feb 27, 2008)

As Magnettica stated this is very common in older homes. I have seen it in homes with K/T, BX and even the older Romex. Usually all the light fixtures are live and there is a switched loop on the neutral leg is what i find.


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## Magnettica (Dec 19, 2006)

The switch loops exists in older homes as well but what I was talking about was the actual switching of the neutral from a feed in, feed out, switch leg of a SG box. Instead of switching the ungrounded conductor, they would actually use the neutral to do the switching. But by wiring it like this there wouldn't be a complete grounded path and if a short-circuit happened there'd be no way to facilitate an overcurrent device. Homes with knob and tube systems have this problem.


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## Ricky&Julian (May 10, 2009)

Magnettica said:


> The switch loops exists in older homes as well but what I was talking about was the actual switching of the neutral from a feed in, feed out, switch leg of a SG box. Instead of switching the ungrounded conductor, they would actually use the neutral to do the switching. But by wiring it like this there wouldn't be a complete grounded path and if a short-circuit happened there'd be no way to facilitate an overcurrent device. Homes with knob and tube systems have this problem.


That is exactly the situation they have. I was 80% comfortable telling them it was common back then, as I am sure I had ran into it before. The other 20% was naggin at me just enough to ask on the forum.

Thanks all for the responses.


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## Celtic (May 23, 2007)

joelv1967 said:


> I think it's a philadelphia circuit.



..you might be thinking of the Philadelphia Experiment or Manhattan Project :blink:




:laughing:


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## Celtic (May 23, 2007)

Magnettica said:


> .... there'd be no way to facilitate an overcurrent device....


:thumbsup:
Good explanation Mags...that there is my favorite part.


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## Magnettica (Dec 19, 2006)

Celtic said:


> :thumbsup:
> Good explanation Mags...that there is my favorite part.


Hell yeah! I loves me some grounding! :laughing:


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## ampman (Apr 1, 2009)

have seen this done by HOs who think because it works its right by the way has anybody seen where neut. were colored blue instead of white or grey


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## Anti-wingnut (Mar 12, 2009)

Magnettica said:


> ........they would actually use the neutral to do the switching. But by wiring it like this there wouldn't be a complete grounded path and if a short-circuit happened there'd be no way to facilitate an overcurrent device........


I can't visualize how over-current protection would be lost in this scenario. Could you help me out here?


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## 480sparky (Feb 1, 2009)

ampman said:


> have seen this done by HOs who think because it works its right by the way has anybody seen where neut. were colored blue instead of white or grey


 
Common in some countries.


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## Magnettica (Dec 19, 2006)

Anti-wingnut said:


> I can't visualize how over-current protection would be lost in this scenario. Could you help me out here?


First, overcurrent and overcurrent device are two different things. To facilitate an overcurrent device (fuses, circuit breaker), one of three things must happen: an overload, a short-circuit, or a ground fault, and there needs to be a complete unbroken path back to the electrical source (transformer). Since we are talking knob & tube wiring, there is no equipment ground so a ground fault would be impossible. So unless a circuit is overloaded the only other way a circuit breaker or fuse would trip would be from a short-circuit. What's a short circuit? An undesired connection between hot and neutral without some form of resistance like that found in a light bulb. If a neutral is wired in series from the light switch to the light bulb, there is only a grounded path when the switch is closed and the light is lit and there is no permanent path back to the source. Did I explain that alright?


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## mrmike (Dec 9, 2008)

These Explanations in this thread make no Sense at all !!!!!!!! Whew!! SCARY !!!!


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## ampman (Apr 1, 2009)

480sparky said:


> Common in some countries.


 i've seen also 240 volt delta black-orange-red-white-green


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## Magnettica (Dec 19, 2006)

mrmike said:


> These Explanations in this thread make no Sense at all !!!!!!!! Whew!! SCARY !!!!


What explanation do you not understand? 

Or are you still mad about the time I told you it was common for furnaces to be installed in attic spaces? 

Knob and tube has (2) conductors. 1 grounded, 1 ungrounded. If the grounded "neutral" conductor is wired in series from a switch to a light, receptacle, whatever... then there is no path for fault current to flow to facilitate an overcurrent device if that switch is in the open (off) position.


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## ampman (Apr 1, 2009)

Magnettica said:


> First, overcurrent and overcurrent device are two different things. To facilitate an overcurrent device (fuses, circuit breaker), one of three things must happen: an overload, a short-circuit, or a ground fault, and there needs to be a complete unbroken path back to the electrical source (transformer). Since we are talking knob & tube wiring, there is no equipment ground so a ground fault would be impossible. So unless a circuit is overloaded the only other way a circuit breaker or fuse would trip would be from a short-circuit. What's a short circuit? An undesired connection between hot and neutral without some form of resistance like that found in a light bulb. If a neutral is wired in series from the light switch to the light bulb, there is only a grounded path when the switch is closed and the light is lit and there is no permanent path back to the source. Did I explain that alright?


 you can still have a ground fault not to a grounding conductor but to something like a water pipe or the like


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## Magnettica (Dec 19, 2006)

ampman said:


> you can still have a ground fault not to a grounding conductor but to something like a water pipe or the like


250.4 (A)(5)

The earth IS NOT an effective ground fault current path. Besides, if a short-circuit happened on the 2nd floor in an old bathroom there is no path at all if that switch is open. The water piping system is never to be used to clear a fault. 250.4 (A)(5)


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## ampman (Apr 1, 2009)

Magnettica said:


> 250.4 (A)(5)
> 
> The earth IS NOT an effective ground fault current path. Besides, if a short-circuit happened on the 2nd floor in an old bathroom there is no path at all if that switch is open. The water piping system is never to be used to clear a fault. 250.4 (A)(5)


 i know the earth is not an effective ground (20 amp breaker to single ground rod not bonded will not trip ocd) but a fault to ground is still a fault even though it may not trip ocd reason for gfis. what does a br on the second floor have to do with it . metal water piping is not meant to clear faults but will if grounded properly at the main by the way how do you know if an electrician is at a party--- because he will tell you


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## Magnettica (Dec 19, 2006)

ampman said:


> i know the earth is not an effective ground (20 amp breaker to single ground rod not bonded will not trip ocd) but a fault to ground is still a fault even though it may not trip ocd reason for gfis. what does a br on the second floor have to do with it . metal water piping is not meant to clear faults but will if grounded properly at the main by the way how do you know if an electrician is at a party--- because he will tell you


How would you have a fault to ground if there is no connection to ground, and what path would the fault current take if there are no paths for it to take?


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## mrmike (Dec 9, 2008)

Your neutral is likely not a neutral but an insulated conductor identified as a GROUNDED conductor but acting as an UNGROUNDED conductor. 
__________________But by wiring it like this there wouldn't be a complete "grounded path" and if a short-circuit happened there'd be no way to facilitate an overcurrent device. Homes with knob and tube systems have this problem. __________________Since we are talking knob & tube wiring, there is "no equipment ground" so a ground fault would be impossible. So unless a circuit is overloaded the only other way a circuit breaker or fuse would trip would be from a short-circuit. What's a short circuit? An undesired connection between hot and neutral without some form of resistance. 
vKnob and tube has (2) conductors. 1 grounded, 1 ungrounded. If the grounded "neutral" conductor is wired in series from a switch to a light, receptacle, whatever... then there is no path for fault current to flow to facilitate an overcurrent device if that switch is in the open (off) position. Please read your explanations & think about it. Also-an example- a duplex receptacle-nothing plugged in--no circuit-right? You take the black wire to earth-ground- What happens??????


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## Magnettica (Dec 19, 2006)

mrmike said:


> Please read your explanations & think about it. Also-an example- a duplex receptacle-nothing plugged in--no circuit-right? You take the black wire to earth-ground- What happens??????


Black wire to earth-ground what happens?

Supply is 120 volts
Earths resistance is 25 ohms

120V/ 25Ω = 4.8 amps

Now try as you may but that 4.8 amps of fault current will not trip a 15-20 amp circuit breaker or fuse. 

_duplex receptacle-nothing plugged in--no circuit-right?_

Here you have a circuit wired in parallel and the current is just waiting there to be used. You plug something in, turn it on, the circuits complete and electrons do work.


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## ampman (Apr 1, 2009)

underground water pipe ran from street into house comes in contact with hot conductor is NOT a ground fault???( and this may or maynot trip ocd bonded -yes not bonded -no


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## sorethumbs (Apr 22, 2009)

Magnettica said:


> The switch loops exists in older homes as well but what I was talking about was the actual switching of the neutral from a feed in, feed out, switch leg of a SG box. Instead of switching the ungrounded conductor, they would actually use the neutral to do the switching. But by wiring it like this there wouldn't be a complete grounded path and if a short-circuit happened there'd be no way to facilitate an overcurrent device. Homes with knob and tube systems have this problem.


Any chance this was done specifically to avoid tripping the OCD? I'd bet a 30-amp service was pretty common back in the K&T days. Two or four 15-amp fuses total for branch circuts. I'm also going to say people didn't have much money to be replacing "expensive" fuses. If I was depression area dirt-poor and had to install a new fuse every time a lightbulb blew I'd be pissed. I'd be looking for "creative" ways to save a few bucks. shove a penny in the fuse holder, switch the neutral, whatever it took.


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## ampman (Apr 1, 2009)

sorethumbs said:


> Any chance this was done specifically to avoid tripping the OCD? I'd bet a 30-amp service was pretty common back in the K&T days. Two or four 15-amp fuses total for branch circuts. I'm also going to say people didn't have much money to be replacing "expensive" fuses. If I was depression area dirt-poor and had to install a new fuse every time a lightbulb blew I'd be pissed. I'd be looking for "creative" ways to save a few bucks. shove a penny in the fuse holder, switch the neutral, whatever it took.


 i hope not


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## Magnettica (Dec 19, 2006)

ampman said:


> underground water pipe ran from street into house comes in contact with hot conductor is NOT a ground fault???( and this may or maynot trip ocd bonded -yes not bonded -no


Dude, I don't even know what you're even talking about anymore.

The commonly referred to "neutral" conductor is actually a current carry conductor (CCC) that is intentionally grounded. If this conductor is disrupted like it would be if used in series from a switch to a light the grounded path is no longer there and a fault on a 2-wire knob & tube system would have no path for fault current to flow. 

Also, forget about using the term "hot" when describing a hot conductor, use the term "ungrounded" like it does in the NEC. 


*Grounded Conductor.* A system or circuit conductor that is intentionally grounded. 

*Grounding Conductor, Equipment.* The conductor used 
to connect the non–current-carrying metal parts of equip- 
ment, raceways, and other enclosures to the system 
grounded conductor, the grounding electrode conductor, or 
both, at the service equipment or at the source of a sepa- 
rately derived system.


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## Magnettica (Dec 19, 2006)

sorethumbs said:


> Any chance this was done specifically to avoid tripping the OCD? I'd bet a 30-amp service was pretty common back in the K&T days. Two or four 15-amp fuses total for branch circuts. I'm also going to say people didn't have much money to be replacing "expensive" fuses. If I was depression area dirt-poor and had to install a new fuse every time a lightbulb blew I'd be pissed. I'd be looking for "creative" ways to save a few bucks. shove a penny in the fuse holder, switch the neutral, whatever it took.


And you can burn a house down that way. If fault current has no place to flow, what do you think will happen to metal parts that could be become energized if they aren't grounded? THEY'LL REMAIN ENERGIZED!!! Then when you do touch something that is grounded you will complete that path and likely die on the spot. So go ahead and be "creative" while saving a few bucks.


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## mrmike (Dec 9, 2008)

Magnettica said:


> Dude, I don't even know what you're even talking about anymore.
> 
> The commonly referred to "neutral" conductor is actually a current carry conductor (CCC) that is intentionally grounded. If this conductor is disrupted like it would be if used in series from a switch to a light the grounded path is no longer there and a fault on a 2-wire knob & tube system would have no path for fault current to flow.
> 
> ...


DUDE!!!!Please Please stop this Nonsense!!!!!!!!!!!!!!!! I am not going to argue with you Either!!! I worked 25 yrs as an industrial electrician & 4 as An electrical Planner- & believe me We used the term "hot" Yes "hot" When describing a hot Conductor- Not an ungrounded !!!! We had 22 Journeyman Electrician !! Get out of the Books man & get out in the Field!!!!!!!!!!!! We don't follow your Circles Jerks & contradictions Man !!!!!! STop!!!!!!!!!!!! Your confused-Don't confuse anyone else with your "watertheology!!!!


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## Celtic (May 23, 2007)

mrmike said:


> DUDE!!!!Please Please stop this Nonsense!!!!!!!!!!!!!!!! I am not going to argue with you Either!!! I worked 25 yrs as an industrial electrician & 4 as An electrical Planner- & believe me We used the term "hot" Yes "hot" When describing a hot Conductor- Not an ungrounded !!!! We had 22 Journeyman Electrician !! Get out of the Books man & get out in the Field!!!!!!!!!!!! We don't follow your Circles Jerks & contradictions Man !!!!!! STop!!!!!!!!!!!! Your confused-Don't confuse anyone else with your "watertheology!!!!



If people used the PROPER terms, we could all understand each other.

It's really a shame that after 30 yrs in the trade, you choose to debate this....


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## ampman (Apr 1, 2009)

Magnettica said:


> Dude, I don't even know what you're even talking about anymore.
> 
> The commonly referred to "neutral" conductor is actually a current carry conductor (CCC) that is intentionally grounded. If this conductor is disrupted like it would be if used in series from a switch to a light the grounded path is no longer there and a fault on a 2-wire knob & tube system would have no path for fault current to flow.
> 
> ...


 when taking a test yes use ungrounded conductor in the feild say hot its easier 
and in my post i did say grounding conductor not grounded conductor
now answer my question is a ungrounded (hot) conductor in contact with a path to ground (water pipe buried in the ground )a ground fault even though it may not trip a ocd


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## ampman (Apr 1, 2009)

mrmike said:


> DUDE!!!!Please Please stop this Nonsense!!!!!!!!!!!!!!!! I am not going to argue with you Either!!! I worked 25 yrs as an industrial electrician & 4 as An electrical Planner- & believe me We used the term "hot" Yes "hot" When describing a hot Conductor- Not an ungrounded !!!! We had 22 Journeyman Electrician !! Get out of the Books man & get out in the Field!!!!!!!!!!!! We don't follow your Circles Jerks & contradictions Man !!!!!! STop!!!!!!!!!!!! Your confused-Don't confuse anyone else with your "watertheology!!!!


 stick to carpentry ok, hold on mabye not that either


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## Magnettica (Dec 19, 2006)

ampman said:


> when taking a test yes use ungrounded conductor in the feild say hot its easier
> and in my post i did say grounding conductor not grounded conductor
> now answer my question is a ungrounded (hot) conductor in contact with a path to ground (water pipe buried in the ground )a ground fault even though it may not trip a ocd


If you have a fault and it's not tripping the circuit breaker, you likely have objectionable current flow. That's when "neutral current" flows on normally non-energized metal parts, like conduit or building steel, and is the result of bonding the GROUNDED parts with the GROUNDING parts anywhere other than at the main disconnect.


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## Magnettica (Dec 19, 2006)

Celtic said:


> If people used the PROPER terms, we could all understand each other.
> 
> It's really a shame that after 30 yrs in the trade, you choose to debate this....


Bravo to that!


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## Celtic (May 23, 2007)

Just substitute ground rod for water pipe, aluminum siding...

[


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## ampman (Apr 1, 2009)

Magnettica said:


> If you have a fault and it's not tripping the circuit breaker, you likely have objectionable current flow. That's when "neutral current" flows on normally non-energized metal parts, like conduit or building steel, and is the result of bonding the GROUNDED parts with the GROUNDING parts anywhere other than at the main disconnect.


 this ain't where we started


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## ampman (Apr 1, 2009)

Celtic said:


> Just substitute ground rod for water pipe, aluminum siding...
> 
> [


 thank you a picture is worth a thousand posts


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## Celtic (May 23, 2007)

ampman said:


> thank you a picture is worth a thousand posts


I'm a man of few words and many posts :blink:



:laughing:


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## Magnettica (Dec 19, 2006)

*215.12 Identification for Feeders.*
(C) Ungrounded Conductors. Where the premises wiring 
system has feeders supplied from more than one nominal 
voltage system, each ungrounded conductor of a feeder, 
where accessible, shall be identiﬁed by system. The means 
of identiﬁcation shall be permitted to be by separate color 
coding, marking tape, tagging, or other approved means 
and shall be permanently posted at each feeder panelboard 
or similar feeder distribution equipment. 

--------------

What the hell are they talking about there? I see nothing that says anything about hot conductors so do we just assume they mean hot conductors, err, feeders????


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## mrmike (Dec 9, 2008)

Magnettica said:


> *215.12 Identification for Feeders.*
> (C) Ungrounded Conductors. Where the premises wiring
> system has feeders supplied from more than one nominal
> voltage system, each ungrounded conductor of a feeder,
> ...


Mag, The code book has always known to be confusing! It is not a field guide for doing electrical work, but a safety guide, a Rule book that we must abide by.... and should. Out in the field, and I am talking everywhere there has been some standards set & not to be confused, for all of our Safety. We use the word "Hot" for a voltage carrying conductor. I just talked to a National Grid long time Supervisor last night & he did not know what I was talking about using the term" ungrounded" instead of Hot.
Man, This Thread got "Hot" Lets let it go !


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## Ricky&Julian (May 10, 2009)

ampman said:


> damn 3 postd and look at what you did --- please keep postingarty:


I will, thanks.

I am starting to feel the love!:thumbup:


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## Magnettica (Dec 19, 2006)

mrmike said:


> Mag, The code book has always known to be confusing! It is not a field guide for doing electrical work, but a safety guide, a Rule book that we must abide by.... and should. Out in the field, and I am talking everywhere there has been some standards set & not to be confused, for all of our Safety. We use the word "Hot" for a voltage carrying conductor. I just talked to a National Grid long time Supervisor last night & he did not know what I was talking about using the term" ungrounded" instead of Hot.
> Man, This Thread got "Hot" Lets let it go !



You spoke to a "National Grid long time Supervisor" and he didn't know what an ungrounded conductor meant? 

Was this the same guy that caused the blackout of 2003 where customers lost power in Ohio, Pennsylvania, New York, Massachusetts, Rhode Island, Connecticut, parts of Canada?


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