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3 prong grounding type receptacles on 2 wire Un-grounded System

By
Home Inspector with NCW Home Inspections, LLC

3 prong grounding type receptacles on 2 wire Ungrounded System. 

                                              A little history

                                Wenatchee Home Inspections



 

We see this all the time during home inspections in homes typically from the early 1960’s backward. Using a grounding type receptacle on a two wire (ungrounded) circuit. Many homeowners (and some inspectors) do not know the rules of replacement on these existing ungrounded systems.



                                         



The practice of putting a three prong (grounded) receptacle on a two wire (ungrounded) circuit has never been allowed. It was in 1984 that a new provision was provided to put 3 prong outlets on ungrounded system if GFCI (Ground Fault Circuit Interrupter) receptacle was used. In this early exception, it was only allowed on the specific GFCI receptacle and no other receptacles outlets.



               





Six years later in 1990 we have the first provision of grounded type receptacles on an ungrounded system to be allowed on the load side of a GFCI receptacle.  This would mean you could now protect several receptacles using one device.



                                              

 


Then in 1993 a small change was introduced that required that all receptacles that are using this exception needed to be marked “GFCl protected. ” This was still not clear to the occupants that there was still no grounding conductor provided.

Then in 1996 they reworked section 210-7(d) to require that “No equipment ground” also had to be indicated on any ungrounded receptacle that was being protected by GFCI device. This is where we are today.

So to follow a little history of these requirements below is the chronology of thecodes in regards to the use of grounded receptacles on an ungrounded circuit.

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First off, grounding of receptacle became required in the 1962 NEC. So we pick up the history in the 1965 code cycle. This is the first requirements that addressed replacement of receptacles on an ungrounded system.

1965 NEC-

210-7. Grounding Receptacles. Receptacles and cord connectors equipped with grounding contacts shall have those contacts effectively grounded. The branch circuit or branch circuit raceway shall include or provide a grounding .conductor to which the grounding contacts of the receptacle or cord connector shall be connected. The metal armor of Type AC metal-clad cable, the sheath of aluminum sheathed cable, or a metallic raceway is acceptable as a grounding conductor. See Sections 210-21(b), 250-45 and 250-59.


Exception: For extensions only in existing installations which do not have a grounding conductor in the branch circuit, the grounding conductor of a grounding-type receptacle outlet may be grounded to a grounded cold water pipe near the equipment.

210-21. Outlet Devices.

(b) Receptacles. Receptacles installed on 15 ampere and 20-ampere branch-circuits shall be of the grounding type and they shall be installed in accordance with Section 210-7.


When grounding type receptacles are used as replacements for existing non-grounding types a grounding conductor installed in accordance with Section 250-57 shall be provided. If it is impractical to reach a source of ground a non-grounding type receptacle shall be used. The installation of grounding type outlets shall not be used as a requirement that all portable equipment be of the grounded type. See Article 250 for requirements for the grounding of portables.


Receptacles required in Section 517-3(d) are considered as meeting the requirements of this Section.

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So through all the 60’s and 70’s it was required to provide a ground to any grounding type of receptacle if it was to be used.  Then in 1984 NEC,  a new exception was introduced, the GFCI protected grounding type of receptacle.

1984 NEC
210-7

(d) Replacements. Grounding-type receptacles shall be used as replacements for existing non-grounding types and shall be connected to a grounding conductor installed in accordance with (c)  above.

Exception: Where a grounding means does not exist in the receptacle enclosure either a non grounding or a ground-fault circuit-interrupter type of receptacle shall be used, provided the ground, fault circuit-interrupter does not supply other receptacles.

From the 1984 Handbook-


“When existing non-grounding-type receptacles are replaced, it is necessary to use

only grounding-type receptacles where a grounding means exists in the receptacle

enclosure. Where a grounding means does not exist, there are three choices.

A non-grounding-type receptacle can be used, thereby indicating to the user that a

grounding means for an appliance is not available.

A grounding type receptacle can be used. See Section 250-50, Exception.

The third choice is a ground-fault circuit-interrupter type of receptacle. If the ground-fault circuit-interrupter type of receptacle is used it shall not supply other receptacles. It can either be the non feed-through type, or a feed-through type wired so that the feed-through feature is not used. For example, the downstream receptacles can be connected on the line side of the ground-fault circuit-interrupter receptacle. Permission to use a ground-fault circuit-interrupter type of receptacle for a non-grounding type of receptacle where no grounding means exists in the box is new in the 1984 NEC. It is based on the ability of the GFCI to provide shock hazard protection whether or not the tool, appliance, etc., connected to it is grounded. A GFCI type of receptacle therefore provides better protection than a non-grounding type of receptacle.

If the GFCI type of receptacle is used, care should be exercised in the installation to be sure the grounding lead of the receptacle is insulated or otherwise kept from contacting uninsulated live parts in the box. Since the box is not grounded in this type of installation, Section 250-74 does not require Bonding the grounding lead to the box See also Section 250-50. Exception.”


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Then we reach 1990’s and now we expand the exception to allow multiple grounding type receptacles to be protected by a GFCI receptacle or device.

 

                                                   


1990 NEC

210-7

(d) Replacements. Grounding-lype receptacles shall be used as replacements for existing non-grounding types and shall be connected to a grounding conductor installed in accordance with (c)  above.

 

Ground Fault circuit-interrupter protected receptacles shall be provided where replacements are made at receptacle outlets that are required to be so protected elsewhere in this Code.

Exception: When a grounding means does not exist in the receptacle enclosure, either a non-grounded  or a ground-fault circuit-interrupter-type of receptacle shall be used. A grounding conductor shall not be connected from the ground-fault circuit-interrupter-type receptacle to any outlet supplied from the ground-fault circuit-interrupter-type receptacle. Existing nongrounding-type receptacles shall he permitted to be replaced with grounding-type receptacles where supplied through a ground-fault circuit-interrupter.

 

1993 NEC

210-7

(d) Replacements. Grounding-type receptacles shall be used as replacements for existing non-grounding types and shall be connected to a grounding conductor installed in accordance with Section 210-7(c).

 

Ground Fault circuit-interrupter protected receptacles shall be provided where replacements are made at receptacle outlets that are required to be so protected elsewhere in this Code.

Exception: When a grounding means does not exist in the receptacle enclosure, either a non-grounded or a ground-fault circuit-interrupter-type of receptacle shall be used. A grounding conductor shall not be connected from the ground-fault circuit-interrupter-type receptacle to any outlet supplied from the ground-fault circuit-interrupter-type receptacle. Existing nongrounding-type receptacles shall be permitted to be replaced with grounding-type receptacles where supplied through a ground-fault circuit interrupter. These receptacle

locations shall be marked “GFCl protected. ”

 



                                           



1996 NEC
210-7

(d) Replacements. Replacement of receptacles shall comply with (I). (2). and (3) below as applicable.


(1) Where a grounding means exists in the receptacle enclosure or a grounding conductor is installed in accordance with Section 250-50(b), Exception, grounding-type receptacles shall be used and shall be connected to wire grounding conductor in accordance with Section 210-7(c) or Section 250-50(b). Exception.


(2) Ground-fault circuit-interrupter protected receptacles shall be provided where replacements are made at receptacle outlets that are required to be so protected elsewhere in this Code.

(3) Where a grounding means does not exist in the receptacle enclosure, the installation shall comply with a. b. ore below:

 

a. A non-grounding-type receptacle(s) shall be permitted to be replaced with another non-grounding-type receptacle(s).

 

b. A non-grounding-type receptacles) shall be permitted to be replaced with a ground-fault circuit-interrupter-type of receptacle(s). These receptacles shall be marked “No Equipment Ground." An equipment grounding conductor shall not be connected from the ground-fault circuit-interrupter-type receptacle to any outlet supplied from the ground-fault circuit-interrupter receptacle.

 

c. A non-grounding-type receptacle(s) shall be permitted to be replaced with a grounding-type receptacle(s) where supplied through a ground-fault circuit-interrupter. Grounding-type

receptacles supplied through the ground-fault circuit-interrupter shall be marked “GFCI Protected" and “No Equipment Ground." An equipment grounding conductor shall not be connected between the grounding-type receptacles.

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So this gets us to where we are today with the use of the GFCI devices as a means of an upgrade. In 2002 the replacement section was relocated to 406.3.  With the most of our modern day electronics needing a ground to help protect the circuitry, it is highly advisable to upgrade your wiring to allow for proper grounding of receptacles.


 


 

 

"This alternating current thing is just a fad. It is much too dangerous for general use."

Thomas Edison

 

 


 








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

 

 


 




NCW Home Inspections, LLC  is a Licensed Washington State Home Inspection service located in Wenatchee Washington serving Chelan County, Douglas County, Kittitas County, Okanogan County and Grant County Washington and the cities of Wenatchee, Leavenworth, Cashmere, Oroville, Cle Elum, East Wenatchee, Quincy and many more…  

 

Your Wenatchee and Chelan Professional Real Estate, Home and Structural Pest Inspection Service

 

Instructor- Fundamentals of Home Inspection-  Bellingham Technical College

 

WA Home Inspector Advisory Licensing Board

 

www.ncwhomeinspections.com                                                   509-670-9572



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Comments (3)

Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

Of course you can put a three-hole receptacle on a wire intended for two.  I see it all the time!

Says he, with a sly grin.

Sep 20, 2017 09:11 AM
Jim Mushinsky
Centsable Inspection - Framingham, MA

Hi Don,

Great information in "consumer" terms yet you might consider a bit more clarity on the "grounded conductors".  The neutral wire and equipment ground wire are grounded conductors.  The absence of an equipment ground prong at the wall receptacle does not mean that the neutral wire becomes ungrounded.

I'm sure you probably already know the differences between the two grounded conductors. The neutral wire grounded conductor normally carries current and the equipment ground wire grounded conductor does not normally carry current.

You write very well and include informative diagrams or photos.  Maybe you would consider writing another blog on the differences between the grounded conductors and the potential hazards with ground loops at two prong receptacles.

Oct 07, 2017 04:49 AM
Donald Hester
NCW Home Inspections, LLC - Wenatchee, WA
NCW Home Inspections, LLC

Jim Mushinsky 

Thank you for the reply. I understand what you are saying and terms get messed up pretty easily.

From an electrical perspective (Code wise), there are three type of conductors-

Ungrounded conductors (What most refer to as hot/line/phase)

Grounded Conductors (What is referred to as Neutral)

Grounding conductors (What is referred to as equipment grounding conductors/bonding conductors).

So on a pre-62 system, we are typical without a "grounding conductor" which is not to be confused with the "grounded conductor". These serve two different purposes and "grounding conductors" are not related to the grounding of the system to the grounding electrode. Hence the confusion with these.

Here is a little information on these conductors-



From EC&M-

"An ungrounded conductor is a circuit conductor that carries current to the load. We usually call ungrounded conductors in a service, feeder, or branch-circuit phase conductors. When working with these, you must be familiar with the National Electrical Code (NEC) regarding proper identification, construction, application, and ampacity."

 

From the 2014 NEC article 100 -definitions-

 

Grounded Conductor.

 

A system or circuit conductor that is intentionally grounded. (This is the neutral and completes the circuit, it too will carry currrent)

 

Grounding Conductor, Equipment (EGC).

 

The conductive path(s) that provides a ground-fault current path and connects normally non–current-carrying metal parts of equipment together and to the system grounded conductor or to the grounding electrode conductor, or both.

 

Informational Note No. 1: It is recognized that the equipment grounding conductor also performs bonding.

Informational Note No. 2: See 250.118 for a list of acceptable equipment grounding conductors.

 

 

With that said, I have felt that the NEC should use slightly different terms to define these conductors to help eliminate the confusion.

In Don's world, we would have instead of "grounded" and "grounding" conductors we would have "Earthing" and "Bonding".

"Earthing," the act of tying the systems to the earth and intentionally earthed conductor.

"Bonding," The act of connecting normally non–current-carrying metal parts of equipment together and to the system "Earthing" conductor or to the "Earthing" electrode conductor.

Thank you again for the comment.

 

Oct 07, 2017 11:57 AM