What article in the NEC covers the connection of a dryer frame to an equipment grounding conductor?

Since then, grounding equipment such as ranges and dryers to a neutral conductor is not permitted!

Existing installations are not required to be changed if they were in compliance of the NEC at the time the installation. So if an electric clothes dryer or electric range was installed in a residence where the dryer branch- circuit wiring had been installed according to pre-1996 NEC rules, the wiring does not have to be changed. Using the grounding strap furnished by the manufacturer to make a connection between the neutral conductor and the frame.

Many have said that there seem to be no inherent risk associated with these pre-1996 installation but in 2018 there was a couple of electrocution attributed to instillation of dryers most likely in older installations. Though I could not confirm the exact dates of build for the buildings the information in the article leads me to believe these are likely older installations.

Obviously we had other electrical issues but this is where having a separate ground and neutral would provide another level of protection. This also why a qualified electrician should always being doing work on rental properties. So we may have to change our thinking on the practice of allowing the bonding of the casing to the neutral.

Here is two links to the articles on the electrocutions-
https://www.star-telegram.com/news/nation-world/national/article210147279.html

https://www.click2houston.com/news/child-electrocuted-in-texas-rental-home-that-mother-says-had-electrical-issues-before


So time to dive into the code… Ready Jump!

Here is the modern requirement that basically come into effect in 1996.

                                            

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.

So in 1999 we move the article that covers the requirement from 250.60  & 250.59 to 250.140 and 250.138 respectively and where we are today.

1999 NEC

250-138. Cord-and Plug-Connected Equipment.

Non-current-carrying metal parts of cord- and plug-connected equipment if grounded, shall be grounded by one of the following methods.

(a) By Means of an Equipment Grounding Conductor.

By means of an equipment grounding conductor run with the power supply conductors in a cable assembly or flexible cord properly terminated in a grounding-type attachment plug with one fixed grounding contact.

Exception: The grounding contacting pole of grounding-type plug-in ground-fault circuit interrupters shall be permitted to be of the movable, self-restoring type on circuits operating at not over 150 volts between any two conductors, or over 150 volts between any conductor and ground.

(b) By Means of a Separate Flexible Wire or Strap.
By-means of a separate flexible wire or strap, insulated or bare, protected as well as practicable against physical damage, where port of equipment.

250-140. Frames of Ranges and Clothes Dryers.

This section shall apply to existing branch-circuit installations only. New branch-circuit installations shall comply with Sections 250-134 and 250-138. 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 grounded in the manner specified by Section 250-134 or 250-i 38; or, except for mobile homes and recreational vehicles, shall be permitted to be grounded to the grounded circuit conductor if all of the following conditions arc 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 No. 10 copper or No. 8 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.

This is the demarcation point. From this point forward we are to provide a grounding conductor and it is the first time they actually specify the grounded conductor size based on material, copper or aluminum.

1996 NEC

250-59. Cord- and Plug-Connected Equipment.

Noncurrent-carrying metal parts of cord- and plug-connected equipment, where required to be grounded, shall be grounded by one of the methods indicated in (a), (b), or (c) below.

(a) By Means of the Metal Enclosure.

By means of the metal enclosure of the conductors supplying such equipment if a grounding-type attachment plug with one fixed grounding contact is used for grounding the metal enclosure, and if the metal enclosure of the conductors is secured to the attachment plug and to equipment by approved connectors.

Exception: A self-restoring grounding contact shall be permitted on grounding-type attachment plugs used on the power supply cord of portable hand-held, hand-guided, or hand-supported tools or appliances.

(b) By Means of an Equipment Grounding Conductor.

By means of an equipment grounding conductor run with the power supply conductors in a cable assembly or flexible cord properly terminated in a grounding-type attachment plug with one fixed grounding contact. An uninsulated equipment grounding conductor shall be permitted, but, if individually covered, the covering shall have a continuous outer finish that is either green or green with one or more yellow stripes.

Exception: A self-restoring grounding contact shall be permitted on grounding-type attachment plugs used on the power supply cord of portable hand-held, hand-guided, or hand-supported tools or appliances.

(c) By Means of a Separate Flexible Wire or Strap.

By means of a separate flexible wire or strap, insulated or bare, protected as well as practicable against physical damage, where part of equipment.

250-60. Frames of Ranges and Clothes Dryers.

This section shall apply to existing branch-circuit installations only. New branch-circuit installations shall comply with Sections 250-57 and 250-59. 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 grounded in the manner specified by Section 250-57 or 250-59; or, except for mobile homes and recreational vehicles, shall be permitted to be grounded to the grounded circuit conductor if all of the conditions indicated in (a) through (d) below are met.

(a) 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.

(b) The grounded conductor is not smaller than No. 10 copper or No. 8 aluminum.

(c) 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.

(d) Grounding contacts of receptacles furnished as part of the equipment are bonded to the equipment.

In 1975 is the first requirement that the circuit for ranges and dryers can use a 3-wire feed as long as it derives from service equipment. The underlined section is where the requirement lies.


                                        

1975 NEC-

250-60. Frames of Ranges and Clothes Dryers.
Frames of electric ranges, wall-mounted ovens, counter-mounted cooking units, and clothes dryers shall be grounded in the manner specified by Section 250-57 or 250-59; or except for mobile homes or travel trailers shall be permitted to be grounded to the grounded circuit conductor if all of the conditions indicated in (a) through (d) below are met.

(a) The supply circuit is 120/240-volt, single-phase, 3-wire; or 120/ 208-volt derived from a 3-phase, 4-wire, wye-connected system.

(b) The grounded conductor is not smaller than No. 10.

(c) The grounded conductor is insulated; or the grounded conductor is uninsulated and part of a service entrance cable and the branch circuit originates at the service equipment.

(d) Grounding contacts of receptacles furnished as part of the equipment are bonded to the equipment.

From 1971 backwards to 1965 this article only recommends that that it derives from service equipment but is not required, unless it is an uninsulated neutral such as used in some SE cables,  then it is still required to originate at the service equipment. (Underlining is mine)

                             

1971 NEC-
250-60. Frames of Electric Ranges and Electric Clothes Dryers.
Frames of electric ranges and electric clothes dryers shall be grounded by any of the means provided for in Sections 250-57 and 250-59; or, where served by a 120/240-volt, single-phase, 3-wire circuit or a 120/208-volt circuit derived from a 3-phase, 4-wire supply, they may be grounded by connection to the grounded circuit conductors, provided the grounded circuit conductors are not smaller than No. 10 AWG.  Where service-entrance cable having an uninsulated neutral conductor is used, the

branch circuit shall originate at the service-entrance equipment. The frames of wall-mounted ovens and counter-mounted cooking units shall be grounded and may be grounded in the same manner as electric ranges. Grounding contacts of receptacles furnished as a part of equip-

ment grounded to the neutral circuit conductor shall be bonded to the equipment which is so grounded.

It is recommended that all branch circuits supplying equipment which is grounded to the grounded circuit conductor originate at the service equipment.

1968 NEC

250-60. Frames of Electric Ranges and Electric Clothes Dryers.  

Frames of electric ranges and electric clothes dryers shall be grounded by any of the means provided for in Sections 250-57 and 250-59: or, where served bv a 120/240 volt, single phase, three-wire circuit or a 120/208, volt circuit derived from a three-phase, four-wire supply, they may be grounded by connection to the grounded circuit conductors, provided the grounded circuit conductors are not smaller than No. 10 AWG.

Where service-entrance cable having an uninsulated neutral conductor is used, the branch circuit shall originate at the service-entrance equipment. The frames of wall-mounted ovens and counter-mounted cooking units shall be grounded and may be grounded in the same manner as electric ranges. Grounding contacts of receptacles furnished as a part of equipment grounded to the neutral circuit conductor shall be bonded to the equipment which is so grounded.

It is recommended that all branch circuits supplying equipment which is grounded to the grounded circuit conductor originate at the service equipment.

In the 1965 NEC this is where we really have no direction on this. Article 250-60 states we can use the grounded conductor with no other provision or guidance other than it cannot be smaller than a #10 AWG conductor. You notice it gives no reference to conductor type, copper or aluminum.

1965 NEC

250-60. Frames of Electric Ranges and Electric Clothes Dryers

Frames of electric ranges and electric clothes dryers shall be grounded by any of the means provided for in Sections 250-57 and 250-59: or, where served bv a 120/240 volt, three wire branch circuit, they may be grounded by connection to the grounded circuit conductors, provided the grounded circuit conductors are not smaller than No. 10 AWG.
The frames of wall mounted ovens and counter-mounted cooking units shall be grounded and may be grounded in the same manner as the electric ranges.

Here is some of the earlier articles covering this and you will notice a change. In 1953 we now have ranges and dryers in this article and in 1951 we only address ranges. So if you happen to had a dryer in 1951 (pretty unlikely) you would have had to provide a grounding conductor.

                             

1953 NEC-
2560. Frames of Electric Ranges and Electric Clothes Dryers.

Frames of Electric Ranges and Electric Clothes Dryers shall be grounded by any of the means provided for in Sections 2557 and 2559 or where served by 120-240 volt, three-wire branch circuits, they may be grounded by connection to the grounded circuit conductors, provided the grounded circuit conductors are not smaller than No 10 AWG.


                                                              

1951 NEC-

2560 Frames of Electric Ranges.

Frames of electric ranges shall be grounded by any of the means provided for in sections 2557 and 2559, or they may be grounded by connection to the grounded circuit conductors.

So this ends our little journey through the codes as it relates to Dryers and Ranges and the use of grounding or grounded conductors.

"The art of teaching is the art of assisting discovery."

Mark Van Doren

If you find any errors or have additional information that would expand on any code, building standards or manufacturer requirements please let me know.

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