Bonded Neutral and Ground in Range/Dryer

[K_Buz]

Can a new 120/240V dryer or range be installed using a 3 wire cord/recept legally if the recept is existing?

I know in my practice, we don't, but I can't find the specific code reference.

 

[jumper]

250.140

250.140 Frames of Ranges and Clothes Dryers. Frames
of electric ranges, wall-mounted ovens, counter-mounted
cooking units, clothes dryers, and outlet or junction boxes
that are part of the circuit for these appliances shall be
connected to the equipment grounding conductor in the
manner specified by 250.134 or 250.138.
Exception: For existing branch-circuit installations only
where an equipment grounding conductor is not present in
the outlet or junction box, the frames of electric ranges,
wall-mounted ovens, counter-mounted cooking units,
clothes dryers, and outlet or junction boxes that are part of
the circuit for these appliances shall be permitted to be
connected to the grounded circuit conductor if all the following
conditions are met.
(1) The supply circuit is 120/240-volt, single-phase, 3-wire;
or 208Y/120-volt derived from a 3-phase, 4-wire, wyeconnected
system.
(2) The grounded conductor is not smaller than 10 AWG
copper or 8 AWG aluminum.
(3) The grounded conductor is insulated, or the grounded
conductor is uninsulated and part of a Type SE serviceentrance
cable and the branch circuit originates at the
service equipment.
(4) Grounding contacts of receptacles furnished as part of
the equipment are bonded to the equipment.

 

[K_Buz]

Thanks...had just found it when you posted it.

 

[acrwc10]

and the branch circuit originates at the
service equipment

This is the where the problem normally exists, many of them don't originate at the main service.

 

[GerryB]

I have been doing some kitchen apartment wiring and the stoves are SE cable, bare neutral. According to the code reference there, 250.140 3 it can stay. No benefit in changing it. But where would a 240 line not come from the main service, you mean in a sub panel?

 

[jumper]

I have been doing some kitchen apartment wiring and the stoves are SE cable, bare neutral. According to the code reference there, 250.140 3 it can stay. No benefit in changing it. But where would a 240 line not come from the main service, you mean in a sub panel?

Correct.

An existing 3 wire SE circuit from a sub panel would be illegal in this install.

 

[goldstar]

Just a small side bar to this, be aware that these units come shipped with the EG and neutral bonded together. Most of the appliance stores ship or sell the homeowner a 3-prong cord irrespective of whether they have a new home or an existing one. If the buyer advises the store that they have a 4-prong outlet and they ship a 4-prong cord, from my experience the delivery people never separate the ground clip in the back of the unit. Might as well have had a 3-prong.:slaphead:

 

[texie]

Just a small side bar to this, be aware that these units come shipped with the EG and neutral bonded together. Most of the appliance stores ship or sell the homeowner a 3-prong cord irrespective of whether they have a new home or an existing one. If the buyer advises the store that they have a 4-prong outlet and they ship a 4-prong cord, from my experience the delivery people never separate the ground clip in the back of the unit. Might as well have had a 3-prong.:slaphead:

I agree. If my experience of what I have seen is any indicator, there are a lot of 4 wire appliances out there with the ground strap installed and a lot of 3 wire units with no ground strap. It's just another case of our American culture of nobody cares about the details until someone gets hurt.

 

[acrwc10]

Just a small side bar to this, be aware that these units come shipped with the EG and neutral bonded together. Most of the appliance stores ship or sell the homeowner a 3-prong cord irrespective of whether they have a new home or an existing one. If the buyer advises the store that they have a 4-prong outlet and they ship a 4-prong cord, from my experience the delivery people never separate the ground clip in the back of the unit. Might as well have had a 3-prong.:slaphead:

I came across this nice bit of "Labeling" (notice the neutral jumper remains connected in both diagrams) I called the LG tech line, that was like talking to a brick wall, They insisted the lable was correct and the jumper was to remain connected to the ground and neutral. When I explained it is a code violation, I was told "that must be a new code" :slaphead: when I asked them to send a message to their engeneering dept. I was told,"we can't do that, they only speak Korean." Long story short the next time I was at Home Depot, there is a new Dryer and the diagram on the back was corrected, I guess they neglected to tell there tech guys.

 

[acrwc10]

Here is the corrected labeling

 

[goldstar]

You still have to pull the metal clip off the neutral terminal on a 4-wire cord connection

 

[acrwc10]

You still have to pull the metal clip off the neutral terminal on a 4-wire cord connection

absolutely, I was just surprized that the LG tech guys would argue (on a 4 wire circuit) that the bonding jumper stay on the ground. I should point out the LG dryer has 2 white wires in it, one is on the terminal block and the other is under the bonding screw with the green wire.

 

[Strife]

Just a small side bar to this, be aware that these units come shipped with the EG and neutral bonded together. Most of the appliance stores ship or sell the homeowner a 3-prong cord irrespective of whether they have a new home or an existing one. If the buyer advises the store that they have a 4-prong outlet and they ship a 4-prong cord, from my experience the delivery people never separate the ground clip in the back of the unit. Might as well have had a 3-prong.:slaphead:

Actually worse.

 

[Little Bill]

This is the where the problem normally exists, many of them don't originate at the main service.

This is just for an uninsulated (bare) neutral. If bare, it has to originate from the main service.

I have been doing some kitchen apartment wiring and the stoves are SE cable, bare neutral. According to the code reference there, 250.140 3 it can stay. No benefit in changing it. But where would a 240 line not come from the main service, you mean in a sub panel?

see above

 

[templdl]

This is just for an uninsulated (bare) neutral. If bare, it has to originate from the main service.




see above

And if you think about it there is a reason that it has to originat at the service. When I think about sharing a EGC and a neutral I conside the fact that the conductor better not be compomised. If there was even a loose connection on it got broke what happens to all of the 120v loads of the appliance? You probably will smoke them. How about a line faulting to the appliance enclosure should you have lost the combo N/EGC conductor? Isn't the combo N/EGR also bonded to the appliance and energizing the enclosure with 120v? If you think about it I often wonder why there haven't been more accidents over the years.

 

[templdl]

Here is the corrected labeling



View attachment 6770

Have you noticed that they labeld the EGC a "NEUTRAL" grounding wire. Interesting.

 

[curt swartz]

And if you think about it there is a reason that it has to originat at the service. When I think about sharing a EGC and a neutral I conside the fact that the conductor better not be compomised. If there was even a loose connection on it got broke what happens to all of the 120v loads of the appliance? You probably will smoke them. How about a line faulting to the appliance enclosure should you have lost the combo N/EGC conductor? Isn't the combo N/EGR also bonded to the appliance and energizing the enclosure with 120v? If you think about it I often wonder why there haven't been more accidents over the years.

I think what Bill is trying to clarify is that it only has to originate from the service panel if the grounded conductor is bare. If the grounded conductor is insulated it can come from any panel.

 

[templdl]

I think what Bill is trying to clarify is that it only has to originate from the service panel if the grounded conductor is bare. If the grounded conductor is insulated it can come from any panel.

Yes I do see his point. What I consider is maintaining the intergrety of that conductor and the reason that wrote the code that way. It would be interesting to find out what advantage the insulated condictor has over the bare conductor that the insulated conductor gets a pardon and the unisulated conductor doesn't.

 

[curt swartz]

Yes I do see his point. What I consider is maintaining the intergrety of that conductor and the reason that wrote the code that way. It would be interesting to find out what advantage the insulated condictor has over the bare conductor that the insulated conductor gets a pardon and the unisulated conductor doesn't.

The same reason you are allowed to use a bare grounded conductor on the supply side of the service disconnect but not after the service disconnect. The grounded conductor is required to be insulated to prevent it being bonded to ground after the main bonding jumper in the service disconnect. Of course anytime you use the grounded conductor to ground the frame of a dryer or cooking equipment there is a good chance it will come into contact with the EGC from other equipment.

 

[templdl]

The same reason you are allowed to use a bare grounded conductor on the supply side of the service disconnect but not after the service disconnect. The grounded conductor is required to be insulated to prevent it being bonded to ground after the main bonding jumper in the service disconnect. Of course anytime you use the grounded conductor to ground the frame of a dryer or cooking equipment there is a good chance it will come into contact with the EGC from other equipment.

Ya I know regarding the appliances. Oh well. One has to wonder that there aren't more accidents.
Thanks