Bare Netural Wire

We are starting a remodel and the existing installation is EMT, no bond wire, and solid bare neutral wire for all the branch circuits. When / why was this done? Was there ever a code that would allow this? i.e. no 250.24
 

Fulthrotl

~~Please excuse the mess. Sig under construction~~
We are starting a remodel and the existing installation is EMT, no bond wire, and solid bare neutral wire for all the branch circuits. When / why was this done? Was there ever a code that would allow this? i.e. no 250.24
nope. it's a grounded conductor. a grounding conductor can be green, green with a yellow
tracer, or bare. but a grounded conductor must be either white, or natural gray....

copper is not a listed color. :p

i'm guessing it was done 'cause someone had some bare wire to burn up, so to speak.
 

m sleem

Senior Member
Location
Cairo
We are starting a remodel and the existing installation is EMT, no bond wire, and solid bare neutral wire for all the branch circuits. When / why was this done? Was there ever a code that would allow this? i.e. no 250.24
Bare neutral inside EMT, if the neutral is CCC that leads to a short circuit. Have there been any problems ?
 

mgookin

Senior Member
Location
Fort Myers, FL
We are starting a remodel and the existing installation is EMT, no bond wire, and solid bare neutral wire for all the branch circuits. When / why was this done? Was there ever a code that would allow this? i.e. no 250.24
What's in the pipe and what voltage are you working with?
 

kwired

Electron manager
Location
NE Nebraska
We are starting a remodel and the existing installation is EMT, no bond wire, and solid bare neutral wire for all the branch circuits. When / why was this done? Was there ever a code that would allow this? i.e. no 250.24
Only the service conductors can have a bare neutral, or possibly open conductors on insulators if permitted to be uncovered conductors. This is in part because on the supply side of service disconnecting means there technically is no equipment grounding conductor, and the grounded service conductor must be bonded to metal enclosures and raceways putting them at the same potential regardless of current on the neutral conductor. Branch circuits or feeders would need to be insulated or at least covered with little or no exceptions. Equipment grounding conductors are permitted to be bare with only a very few limited cases where they are required to be insulated.
 

m sleem

Senior Member
Location
Cairo
Could you explain please.
I would have thought that this situation would only lead to a dangerous parallel current path/flow, not a short/fault condition.
Ok, i'm mistaken, the parallel path in EMT will just lead to some excessive in heat, but when we have a short circuit with neutral that will be an electrical shock as long as the conduit is touched with the other non-carrying cureent metal parts.
 

kwired

Electron manager
Location
NE Nebraska
Ok, i'm mistaken, the parallel path in EMT will just lead to some excessive in heat, but when we have a short circuit with neutral that will be an electrical shock as long as the conduit is touched with the other non-carrying cureent metal parts.​
heating is not as much of a problem as voltage drop on the exposed "conductor" that is the raceway, which will leave voltage potential between that conductor (the raceway in this case) and grounded objects.

That voltage may not be very much in most cases, but anytime a conductor is carrying current there is some voltage drop and this voltage drop is imposed on all conductive paths bonded to that conductor whether intentional or incidental. By doing this on the load side of service disconnecting means you potentially can energize a portion of, or even the entire equipment grounding conductor network with whatever voltage drop is present on the neutral of the offending circuit that created the condition.

That is the simple explanation, thing is if the EGC (includes the metal raceway) is also carrying current then the amount of voltage drop and where it occurs gets more complex.​
 

jumper

Senior Member
Ok, i'm mistaken, the parallel path in EMT will just lead to some excessive in heat, but when we have a short circuit with neutral that will be an electrical shock as long as the conduit is touched with the other non-carrying cureent metal parts.​



I do not know about the excessive heat, but I agree that it creates a dangerous shock hazard.​
 

kwired

Electron manager
Location
NE Nebraska
I do not know about the excessive heat, but I agree that it creates a dangerous shock hazard.
Should that neutral conductor develop an open circuit condition, then yes you have an even higher potential voltage condition on the raceway and other items bonded to it as they are trying to carry 100% of the neutral current at that point, but even without an open neutral condition there is still a small voltage imposed on things as I mentioned before from simple voltage drop on the neutral conductor. The more current the neutral is carrying the higher that voltage drop may be.
 

dhalleron

Senior Member
Location
Louisville, KY
I don't know when if ever it was legal but I have seen it often around Louisville, KY.

One place is the original Stock Yards Bank. I've seen it in a lot of very old commercial buildings and in some residential. I even saw an armored cable (AC or BX) with a bare neutral. It had a black, red and bare wire in it. I only saw that last one in one old house about a year ago.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
I do not know about the excessive heat, but I agree that it creates a dangerous shock hazard.
I really don't see it as a dangerous shock hazard. The only voltage to drive the shock is the voltage drop on the grounded conductor. If the grounded conductor would be opened, then the conduit would be carrying the current and you would have voltage drop on it, but it would have to be a very large ampacity circuit before that voltage would rise to dangerous assuming tight connections at the conduit couplings and termination points.

If the grounded conductor is not open, I don't see much in the way of heat on the conduit. The only voltage that could drive current on the conduit is the voltage drop on the grounded conductor. That will not result in enough current to produce an excessive amount of heat.

Note, that the connection of the grounded conductor to an EGC (the raceway) would be a code violation, and there are combinations of conditions that could create a hazard. 250.24(A)(5)
 

kwired

Electron manager
Location
NE Nebraska
This situation was normal when ranges were commonly supplied by three conductor SE cable, but there was exception to the general rules that allowed ranges to be connected that way.
 

Fliz

Member
Location
San Francisco
I feel sorry for whoever the electrician was who did that.

To me, if this was an automobile forum, the equivalent question would be: "My car has window washing fluid instead of coolant in the radiator. Was this ever a practice?"
 

Fliz

Member
Location
San Francisco
I really don't see it as a dangerous shock hazard. The only voltage to drive the shock is the voltage drop on the grounded conductor. If the grounded conductor would be opened, then the conduit would be carrying the current and you would have voltage drop on it, but it would have to be a very large ampacity circuit before that voltage would rise to dangerous assuming tight connections at the conduit couplings and termination points.

If the grounded conductor is not open, I don't see much in the way of heat on the conduit. The only voltage that could drive current on the conduit is the voltage drop on the grounded conductor. That will not result in enough current to produce an excessive amount of heat.

Note, that the connection of the grounded conductor to an EGC (the raceway) would be a code violation, and there are combinations of conditions that could create a hazard. 250.24(A)(5)
I'm thinking though that since the equipment ground forms a grid and the neutral current of all bare neutral circuits would then have the same potential as all the conductive equipment grounds and equipment, then anything with even a small difference in potential throughout the building, like a metal fence post or a stair rail, could see a lot of current between the two.
 

GoldDigger

Moderator
Staff member
I feel sorry for whoever the electrician was who did that.

To me, if this was an automobile forum, the equivalent question would be: "My car has window washing fluid instead of coolant in the radiator. Was this ever a practice?"
To which I would answer yes, probably. :)
The earliest radiator coolant was just water, and it is not necessary (just desirable) to add detergents etc. to window washing fluid.

I would not be surprised if at one time methanol was added to coolant as anti-freeze, just as it is currently used as anti-freeze to fill window washers
 
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don_resqcapt19

Moderator
Staff member
Location
Illinois
I'm thinking though that since the equipment ground forms a grid and the neutral current of all bare neutral circuits would then have the same potential as all the conductive equipment grounds and equipment, then anything with even a small difference in potential throughout the building, like a metal fence post or a stair rail, could see a lot of current between the two.
How would there be a lot of current? The path will have a high resistance there there will be very little voltage to drive the current. The only voltage to drive the current is the voltage drop on the grounded conductor, again this assumes that there are no high resistance connections in the grounded conductor.
 

kwired

Electron manager
Location
NE Nebraska
I feel sorry for whoever the electrician was who did that.

To me, if this was an automobile forum, the equivalent question would be: "My car has window washing fluid instead of coolant in the radiator. Was this ever a practice?"
Both the OP and that question seem somewhat expected to me, especially if coming from someone that has little experience in the respective area.

People come to such forums to learn things, or to teach what they do know, and not all are on the same experience level.
 
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