10-2 wg for electric dryer

[Don Hawley]

I just did a re-inspect after a FPE panel replacement. All went well until I realized the installer had reused a 3 prong 30 amp surface mount dryer receptacle attached to the side of the new service panel. My problem is they used 10-2 wg for the feed using the bare "ground" wire as the neutral. Am I correct that this is not allowed and can someone please supply the code reference? Also I believe the neutral must be insulated except when part of the service entry cable, Is this correct. I am not going to argue with sparky over not installing a 4 wire feed to the dryer receptacle although I did recommend it.

[Jerry Peck]

I am not going to argue with sparky over not installing a 4 wire feed to the dryer receptacle although I did recommend it.

My question is this: Being as you are not going to argue over not installing a 4-wire feeder ... then why are you looking for an insulated neutral for a 240 volt circuit which only requires the two ungrounded (hot) conductors and a ground (bare or insulated)?

Now, if ... IF ... if you were going to argue over the lack of installing a 4-wire feeder (as is required for clothes dryers, going back to maybe the early 1990s from memory), then there would need to be an insulated neutral in addition to the two ungrounded hot conductors and the ground (bare or insulated).

Thus my confusion.

[Jim Port]

Was this newly installed or existing? Was the cable NM or SE? It makes a difference.

[Dom D'Agostino]

I mostly see new panel upgrades with all older, original circuits left unchanged (including dryer wiring remaining the same as it was before the new panel).

[Jerry Peck]

I see the word I missed (didn't read correctly);


I ... installer had reused a 3 prong 30 amp surface mount dryer receptacle ...

"reused"

If it was there before and they didn't alter the wire from the panel to the receptacle, then they are allowed to remove the wire from its breaker connection, replace the panel, then reattach to a new breaker.

Otherwise, every breaker replacement would mean bring the circuit to current code, which I'm sure we would all agree is not feasible.

However, and this is where there will likely be some disagreement, if the wire and receptacle was removed (such as to allow for a physically larger panel) and then reinstalled ... that is a re-use of old material and would need to replaced to meet current code, unless the building official wrote a letter specifically approving its re-use (building officials are THE AHJ and are given the authority to "approve" things, within limitations).

[Jim Port]

A dryer is not a straight 240 load. The motor, lights and controls are all 120 volt. The heating elements are 240. Therefore it requires a neutral. Type 10-2 NM was not allowed as the bare is the grounding conductor. Type SE cable was allowed since the bare conductor is a neutral. The ground was bonded to the neutral at the dryer frame on a 3 wire installation.

[Gunnar Alquist]

The ground was bonded to the neutral at the dryer frame on a 3 wire installation.

Wait... WHAT?!? :shocked:

[Jim Port]

Wait... WHAT?!? :shocked:

True, this was allowed. Now with the 4 wire requirements you have separate neutrals and grounds for the dryer.

[Jerry Peck]

That's why older range and dryer receptacles were 3-prong, and newer range and dryer receptacles are 4-prong - so as to not 'energize' the metal appliance cabinet.

That's one reason why HIs check appliances with voltage sniffers, to verify grounding of the metal appliance cabinet.

[Jerry Peck]

Type 10-2 NM was not allowed as the bare is the grounding conductor. Type SE cable was allowed since the bare conductor is a neutral. The ground was bonded to the neutral at the dryer frame on a 3 wire installation.

The bare conductor on SE cable is only a neutral when used as SE cable with the ground also being the neutral. The conductor itself was not, to my recollection, a "neutral" conductor, it was allowed to be used as an uninsulated neutral conductor by the code when used for SE conductors.

I've seen 2-conductor NM cable, not SE cable, used for ranges and dryers for decades ... at least I don't remember seeing SE for those uses.

That was back before the early 1990s (I'm thinking that the change possibly was in the 1993 NEC?, but not sure).

[Speedy Petey]

The bare conductor on SE cable is only a neutral when used as SE cable with the ground also being the neutral. The conductor itself was not, to my recollection, a "neutral" conductor, it was allowed to be used as an uninsulated neutral conductor by the code when used for SE conductors.Not true. It was expressly allowed to be used as a neutral for dwelling electric dryers and ranges.


I've seen 2-conductor NM cable, not SE cable, used for ranges and dryers for decades ... at least I don't remember seeing SE for those uses.I've seen plenty of SE cable for both dryers and ranges, and it was legal at the time.
"2-wire" NM cable was NEVER legal nor allowed for either.



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, wye-connected
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 service-entrance 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.

[Rollie Meyers]

I agree with Speedy Petey, 10/2 NM was never allowed for a dryer, it has never been permitted to use a bare equipment grounding conductor as a neutral, the same thing would apply to 8/2, or 6/2, NM for a range not being code compliant ever either.


A common misconception is that the "L" shaped prong is a ground, read the info on the face of the receptacle, 30A 125/250V, which makes it a dual voltage, non-grounding device,

[Jerry Peck]

I've seen 2-conductor NM cable, not SE cable, used for ranges and dryers for decades ... at least I don't remember seeing SE for those uses.

The code section says NM was not allowed, so as I said above :D at least I don't remember seeing SE ... but apparently SE is what I saw, just not something I remember.

[Don Hawley]

Not true. It was expressly allowed to be used as a neutral for dwelling electric dryers and ranges.

I've seen plenty of SE cable for both dryers and ranges, and it was legal at the time.
"2-wire" NM cable was NEVER legal nor allowed for either.



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, wye-connected
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 service-entrance 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.


Thanks Jim and Speedy I was sure I was right just could not find the reference. Sparky replaced it with 4 wire and 4 prong.