Oven 3 wire question

Jpflex

Senior Member
Location
Victorville
Occupation
Electrician commercial and residential
Customers new double oven is 4 wire. Existing branch circuit is 3 wire. No problem, I thought, we run into this all the time. So I read the installation notes and it says “connect the oven ground and oven neutral together to the branch circuit neutral (white)”. But of course we don’t have a neutral, only a ground. I try calling GE and they say we can’t call technicians anymore but she hesitates and gives me a tech number. He says he can’t help me as he reads the instructions. Do I chance voiding warranty and connect them to the ground? Is the instruction worded wrong? I asked these questions to the tech, he was not much help.
I thought code allowed neutral and ground to be bonded at ONLY ONE LOCATION to avoid objectionable current. This point being the first point of disconnect
 

ActionDave

Chief Moderator
Staff member
Location
Durango, CO, 10 h 20 min without traffic from wing
Occupation
Licensed Electrician
I thought code allowed neutral and ground to be bonded at ONLY ONE LOCATION to avoid objectionable current. This point being the first point of disconnect
Up until the last decade of the twentieth century the neutral was allowed to pull double duty as an equipment grounding conductor for dryers and ranges in dwelling units.
 

kwired

Electron manager
Location
NE Nebraska
Up until the last decade of the twentieth century the neutral was allowed to pull double duty as an equipment grounding conductor for dryers and ranges in dwelling units.
And after that change the only allowances were to let existing installs remain though there is conditions that can sometimes not allow you to leave something that was existing, usually those installs were not totally compliant back when they were new though. New circuit in an older building must still run separate grounding and grounded conductors.
 

norcal

Senior Member
Though when dealing with a dryer, you can run 10-3 no ground, but can't run 10-2/WG even though all conductors are 10 AWG in either case, and probably would be with SE cable if you can find any. Have seen old SE cable in sizes that small but all were from ~1950 or earlier.

With a range circuit many cases there is nothing wrong with 6 AWG ungrounded conductors and 10 AWG grounded conductor either - if say you were running conductors in raceway.

I'm not certain they have a real justified reason for some the requirements here, but at same time it all comes down to allowing something that once was allowed to remain for existing installs, new installs the grounded conductor needs to be white (or gray) and EGC needs to be a separate conductor that is bare, green or green with yellow stripes, or can also be a qualifying metallic wiring method as the EGC.
Around here it was common to run the AL SE cable for the dryer.
 

_SAK_

Member
Location
Illinois
I prefer when gas ranges use a black iron dielectric union to stop nuisance current (ground loops).

I would agree that using a 3 wire and connecting neutral to ground is a code violation. Imagine if you did that from a sub/panel...now you have current on EGC, gas/water pipes, ducts, etc. It might not cause any issue from the main panel where the bond is, but it still is a violation I believe.

I would agree you've got to run a new line if the appliance needs an ungrounded conductor. But not all of them actually require it and can be configured to just use EGC and L1 L2. So if coming from a sub panel and installing 3-wire and the appliance allows this it should be EGC and NOT the grounded conductor.

We've seen some appliances that put current onto the EGC. Hopefully these designs have been improved.
 

tortuga

Code Historian
Location
Oregon
Occupation
Electrical Design
The specific situation the OP StephenFyeager is in is unfortunate, where there is a existing kitchen probably being remodeled, 8/2 with gound romex to built in doubble ovens that are being replaced.

I bet the nameplate of the existing ovens is '240V' and the nameplate of the new ovens is '120/240'
I caught the same mistake on a recent kitchen remodel and gave the client a choice
just return the oven for a different model with a '240V' nameplate
or pay $$$$ to rip open the floors and ceilings (2 story house no basement) to run a new 8/3 with ground.
Here is a link to the '240V' oven:
https://www.lg.com/us/cooking-appliances/lg-wdes9428f-double-wall-oven
So they do make them.

I think electricians need to push this issue back on manufacturers in a big way, complain to whatever trade groups you all belong to and get them to lobby for us, ovens and ranges do not need a '120V' leg at all for cooking on low like the did in the 1940's.
If all new ranges / ovens and cook tops were rated just '240' all those old SE cables would be just fine and new builds could use 8/2 NM.
I can live with 4 wire dryers, but the #8 neutral to just power a electronic circuit board and a light is a real waste of copper nationwide.
 

ActionDave

Chief Moderator
Staff member
Location
Durango, CO, 10 h 20 min without traffic from wing
Occupation
Licensed Electrician
I've hooked up european models of ranges and electric dryers and they are straight 240V. The funny thing is on models made to sell in the US there is a lug to land a neutral that goes nowhere. I think it is there to stop people from returning the appliance to the store, or maybe to reduce calls to tech support.
 

kwired

Electron manager
Location
NE Nebraska
I prefer when gas ranges use a black iron dielectric union to stop nuisance current (ground loops).

I would agree that using a 3 wire and connecting neutral to ground is a code violation. Imagine if you did that from a sub/panel...now you have current on EGC, gas/water pipes, ducts, etc. It might not cause any issue from the main panel where the bond is, but it still is a violation I believe.

I would agree you've got to run a new line if the appliance needs an ungrounded conductor. But not all of them actually require it and can be configured to just use EGC and L1 L2. So if coming from a sub panel and installing 3-wire and the appliance allows this it should be EGC and NOT the grounded conductor.

We've seen some appliances that put current onto the EGC. Hopefully these designs have been improved.
The gas ranges shouldn't have a ground loop through them as there shouldn't be any current on the EGC and the grounded conductor (neutral) shouldn't be bonded in the appliance. If there is stay current there is a problem somewhere and likely not with the appliance.

You seem to have terminology turned around? ungrounded conductor is the two "hots".
grounded conductor is the one that is intentionally grounded - usually the neutral but is cases where it is not a neutral like corner grounded delta or even 2 wire single phase supplies.

EGC is extended from the grounded conductor but is separated from the grounded conductor everywhere past the main or system bonding jumper, whichever applies. Older codes once allowed ranges, dryers, and feeders to separate buildings/structures to use the grounded conductor for also bonding the appliance or allowed grounding again at the separate building/structure, usually with some circumstances that need to be met and those are still carried over as exceptions for existing installations mostly to allow them to remain the way they are presuming they were done correctly when they was installed.
 

tortuga

Code Historian
Location
Oregon
Occupation
Electrical Design
The gas ranges shouldn't have a ground loop through them as there shouldn't be any current on the EGC and the grounded conductor (neutral) shouldn't be bonded in the appliance.
I figured he was referring to dual fuel ranges, where you have an electric convection oven and a gas cooktop all in one range.
In that case we could have the old 3-wire style range receptacle, the N-G bond in the range would be bonding a neutral to a gas pipe.
Now say the service looses a neutral to the building in a storm but the two hots are undamaged, typical if a messenger wire snaps, one could see significant current on that gas pipe.
Fortunately the last dual fuel range I installed was a '240V' model, the neutral was not connected to anything:

So if it was connected to an old SE cable all one would need to do is swap out a NEMA 10-50 to a 6-50 receptacle.
Wich I really think should be the solution for all these.
1664198673666.png
 

norcal

Senior Member
I figured he was referring to dual fuel ranges, where you have an electric convection oven and a gas cooktop all in one range.
In that case we could have the old 3-wire style range receptacle, the N-G bond in the range would be bonding a neutral to a gas pipe.
Now say the service looses a neutral to the building in a storm but the two hots are undamaged, typical if a messenger wire snaps, one could see significant current on that gas pipe.
Fortunately the last dual fuel range I installed was a '240V' model, the neutral was not connected to anything:

So if it was connected to an old SE cable all one would need to do is swap out a NEMA 10-50 to a 6-50 receptacle.
Wich I really think should be the solution for all these.
View attachment 2562280
That is a grounding receptacle 50A 250V, and the 3-wire range receptacle is a dual voltage, non-grounding device 50A 125/250V, 2 different non interchangeable items.
 
Location
New York
Occupation
Electrical apprentice
I agree that the about the bare wire in se cable is the grounded neutral conductor but if you mean the bare wire in nm “Romex” is neutral I’d have to disagree that’s most definitely the ground and to the best of my knowledge is not allowed to be used as a neutral for a dryer or stove receptacle. Romex really shouldn’t be used for either unless it’s 10/3 with ground and a 4 wire receptacle
What makes you say that it's a ground and not a neutral? Is it a bare in NM?

A bare SE cable conductor and an insulated NM cable conductor are neutrals.
 
Location
New York
Occupation
Electrical apprentice
I agree that the about the bare wire in se cable is the grounded neutral conductor but if you mean the bare wire in nm “Romex” is neutral I’d have to disagree that’s most definitely the ground and to the best of my knowledge is not allowed to be used as a neutral for a dryer or stove receptacle. Romex really shouldn’t be used for either unless it’s 10/3 with ground and a 4 wire receptacle
@LarryFine
 

tortuga

Code Historian
Location
Oregon
Occupation
Electrical Design
That is a grounding receptacle 50A 250V, and the 3-wire range receptacle is a dual voltage, non-grounding device 50A 125/250V, 2 different non interchangeable items.
Actually with the range I posted a link to and any other range with a 240 volt nameplate they are, since the namplate of that range is 240 volts, it required no neutral.
So the old SE cable was converted from a bare neutral to a EGC.
 
Location
New York
Occupation
Electrical apprentice
He didn't say that. He said the bare conductor is SE cable is the grounded/neutral conductor, and the insulated conductor in NM is the grounded/neutral conductor. He maybe should have said "white" insulated, but that was what he was referring to.
Gotcha. Am I right by thinking the bare ground of a Romex was never intended to carry that neutral current and that only the neutral of a se cable was meant to ever do that? And that the “w” terminal or L shaped prong on a three wire receptacle is indeed neutral and not ground?
 

macmikeman

Senior Member
The key factor is the bare 3rd wire coming from the service panel or a sub panel? If it is not the service disconnecting panel , it won't meet code and never did. Having said that , it was a fairly common practice to ignore the Service part of the story back in the days of three wire oven outlets and the old-timer inspectors would pass the jobs generally, probably because they were taught that's how it is done when they were in the field working.
 
Location
New York
Occupation
Electrical apprentice
The key factor is the bare 3rd wire coming from the service panel or a sub panel? If it is not the service disconnecting panel , it won't meet code and never did. Having said that , it was a fairly common practice to ignore the Service part of the story back in the days of three wire oven outlets and the old-timer inspectors would pass the jobs generally, probably because they were taught that's how it is done when they were in the field working.
Not sure if you were responding to my post @macmikeman but yes I know you can’t have a a three wire come from a sub panel because g/n is separate after and that neutral is bare even with the se cable. I really just want to know that the “w” on the receptacle is strictly for a neutral connection and a bare ground is not acceptable
 

macmikeman

Senior Member
Not sure if you were responding to my post @macmikeman but yes I know you can’t have a a three wire come from a sub panel because g/n is separate after and that neutral is bare even with the se cable. I really just want to know that the “w” on the receptacle is strictly for a neutral connection and a bare ground is not acceptable
Didn't even read your thread, but carry on ! You seem to have a good handle on this.
 

kwired

Electron manager
Location
NE Nebraska
I figured he was referring to dual fuel ranges, where you have an electric convection oven and a gas cooktop all in one range.
In that case we could have the old 3-wire style range receptacle, the N-G bond in the range would be bonding a neutral to a gas pipe.
Now say the service looses a neutral to the building in a storm but the two hots are undamaged, typical if a messenger wire snaps, one could see significant current on that gas pipe.
Fortunately the last dual fuel range I installed was a '240V' model, the neutral was not connected to anything:

So if it was connected to an old SE cable all one would need to do is swap out a NEMA 10-50 to a 6-50 receptacle.
Wich I really think should be the solution for all these.
View attachment 2562280
If you lose service neutral you run risk of gas piping carrying or attempting to carry neutral current even if you don't have such a range, as well as other metallic piping and communications cable shields, jackets, etc.
 
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