Branch Circuit Extension on Older Ungrounded Wiring Systems
The Wenatchee Home Inspector
This is one of of those dilemmas when purchasing an older home, dealing with an older electrical system. Homes pre -1960's (1962 to be more exact) typically will have no grounding conductor for the wiring system, or if they do such as later 1950's wiring, they often cut the ground off because they did not know what to do with it.
The issue was these older systems where designed for their era. We did not have all the electronics and needs from an electrical system we have today. So quite often people get into their new home and need to make some upgrades to the system to handle their modern needs.
(What is a Sufficient Number of Receptacles? A historical review).
As the example in the photo often people start tinkering with the system and get themselves into an area they just do not have a complete enough knowledge of the codes and how the electrical system works.
So happy Mr. and Mrs. New Home Owner want to take on a new project and updating and adding some new receptacles in the home. Heck they have them old dingy 2 prong outlets that just do not fit the decor of the freshly painted wall.
Typically they have a friend or family member that has some knowlege so they dive in. Hey I see them do it on the DIY shows, it can't be that hard, and heck electricians are expensive. So lets replace some of the old two prong receptacles with new clean white three prong receptacles (outlets) and while we are at it lets add some new ones so it is more conventiant to plug in our other fun electrical toys. Off to the races they go but they just entered uncharted territory for newby home owners.
But they needed to ask some fundimental questions, can you extend an ungrounded branch circuit without a grounding conductor?
Or, can you extend an ungrounded circuit without an equipment grounding conductor as long as you provide GFCI protection and mark it “GFCI Protected, No Equipment Ground”? Which when replacing existing receptacles is actually okay.
Unfortunatley the answer to these questions is “NO” 
From the NEC Handbook-
Section 250.130(C) applies to both ungrounded and grounded systems, but its most common application is for receptacle replacement of branch-circuit extensions in single-phase, 120-volt, 15- and 20-ampere branch circuits, which are required to be supplied by a grounded system per 250.20(B). This section permits a non-grounding-type receptacle to be replaced with a grounding-type receptacle under the following conditions:
The branch circuit does not contain an equipment ground.
An existing branch circuit is being extended for additional receptacle outlets.
An EGC is connected from the receptacle grounding terminal to any accessible point on the grounding electrode system, to any accessible point on the grounding electrode conductor, to the grounded service conductor within the service equipment enclosure, to the equipment grounding terminal bar in the enclosure from which the circuit is supplied, or to an EGC that is part of another branch circuit that originates from the same enclosure where the branch circuit for the receptacle originates.
The requirement in 250.68(C)(1) does not permit this separate EGC to be connected to the metal water piping of a building or structure beyond the first 5 feet of where the piping enters the building or structure unless the conditions of the exception to 250.68(C)(1) can be met.
This method is also permitted to ground a replacement 3-wire receptacle in the existing ungrounded box on the left, where no grounding conductor is available.
So here is the code for the grounding conductor requirement-
Same in both 2014 and 2017 NEC-
250.130 Equipment Grounding Conductor Connections
(C) Nongrounding Receptacle Replacement or Branch Circuit Extensions.
The equipment grounding conductor of a grounding-type receptacle or a branch-circuit extension shall be permitted to be connected to any of the following:
(1) Any accessible point on the grounding electrode system as described in 250.50
(2) Any accessible point on the grounding electrode conductor
(3) The equipment grounding terminal bar within the enclosure where the branch circuit for the receptacle or branch circuit originates
(4) An equipment grounding conductor that is part of another branch circuit that originates from the enclosure where the branch circuit for the receptacle or branch circuit originates
(5) For grounded systems, the grounded service conductor within the service equipment enclosure
(6) For ungrounded systems, the grounding terminal bar within the service equipment enclosure
So this leaves us with a fundemental question for ungrounded systems, If we need to provide a grounding conductor back to the grounding terminal bar within the service equipment enclosure or some other approved place to provide the required ground, why not just run new wire and make it all correct. Not much harder to run a cable than an individual conductor.
"Positive thinking will let you do everything better than negative thinking will."
Zig Ziglar
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
You can follow me on Facebook, Twitter, Google+ and on my website Blog.
“Intelligence is the ability to adapt to change.”
Stephen Hawking
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
You can follow me on Facebook, Twitter, Google+ and on my website Blog.
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