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How to Ground a Nongrounding-type Receptacle

by Gerald C. Newton

  Many older homes do not have grounding conductors in the older romex and are wired with two prong receptacles. So what happens when you live in one of these places and want to connect your computer and printers? It is hardly advisable to cut the grounding terminal off the plugs and energize 3 to 4 thousand dollars worth of equipment without a grounding conductor. Is there a way to accomplish this task without moving out? The 1996 NEC contains a load of changes on replacing a nongrounding-type receptacle, and we might as well repeat this treatise here, just for old times sake. It says in 210-7(d) -now I hope you are ready for this - because it is a mouthful - Replace a nongrounding-type receptacle with a grounding-type if there is an equipment grounding conductor available and connect the grounding conductor. If there is no equipment grounding conductor then replace with a nongrounding-type receptacle or a GFCI type that is marked "No Equipment Ground," or a grounding type if it is protected by a GFCI and marked "GFCI Protected" and marked "No Equipment Ground."

An equipment grounding conductor shall not be connected from the GFCI receptacle that does not have an equipment grounding conductor to any other outlet supplied by the GFCI receptacle, and an equipment grounding conductor shall not be connected between grounding-type receptacles that are protected by a GFCI type receptacle that has no equipment grounding conductor.

Got that! Good. And they wonder why electricians are paid so much. After all this we still don't have a grounding conductor for our computer if there isn't one available in the first place. But wait, all we have to do is go to another Code making Panel and see what they have to say on this. Panel No. 2 writes Article 210, but Panel No. 5 writes Article 250. And in 250-50(a)and(b) Exception it states, "For replacement of nongrounding-type receptacles with grounding-type receptacles and for branch-circuit extensions only in existing installations that do not have an equipment grounding conductor in the branch-circuit, the grounding conductor of a grounding-type receptacle outlet shall be permitted to be grounded to any accessible point on the grounding electrode system as described in 250-81." And.... the 1996 Code will allow this connection at any accessible point on the grounding electrode conductor.

So we can add a grounding-type receptacle to an existing system that does not have an equipment grounding conductor and ground the grounding terminal to the first 5 feet of water pipe that enters the building if this pipe is metal and part of the grounding electrode, or connect it to any accessible point on the grounding electrode conductor (after the 1996 NEC is adopted).

Now anyone knows, you just don't run a wire anymore without finding out all the rules that apply. Installing this grounding wire is no exception. There are rules on the color, the size, the correct wiring method, physical protection, and even workmanship.

Let's start with the color. The NEC tells us in two places (310-12(b) and 250-57(b)) about the color of the grounding conductors. The grounding conductor must be green, bare, or green with one or more yellow stripes with exceptions for insulated conductors larger than No. 6 and conductors in multiconductor cables.

Next, let's address size. The size is based on the overcurrent device protecting the circuit. We use Table 250-95 for this. For a 15 ampere overcurrent protective device a No. 14 copper or No. 12 aluminum conductor is required. For a 20 ampere overcurrent device a No. 12 copper or No. 10 aluminum conductor is required.

What about the wiring method? In general conductors must be run in cables or raceways. Open conductors are allowed using several wiring methods such as cable trays, concealed knob and tube, and open wiring on insulators. But none of these would apply here. Exceptions have been made in several places to allow the equipment grounding conductor for the grounding-type receptacle that has been added to a circuit where no equipment grounding conductor is available to be run separate from the other circuit conductors and to run by itself without a cable or raceway. If you want to follow the Code on why this equipment grounding conductor can be run separate from the circuit conductors go to 300-3(a) and (b) exception, then to 250-57(b) exception No. 3. To follow the Code on why this conductor can be run by itself without a cable or raceway go to 250-92(c)(2) and the exception.

To summarize what we have so far: For a 15 or 20 ampere circuit we can run a No. 12 copper that is bare or green or green with one or more yellow stripes by itself so as not to be subject to physical damage from the receptacle grounding terminal to the grounding electrode as described in 250-81 or, after the 1996 NEC is adopted, to any accessible point on the grounding electrode grounding conductor . We can also use a No. 10 aluminum equipment grounding conductor with some restrictions found in 250-92(a). One restriction is where used outside aluminum grounding conductors cannot be installed within 18 inches of the earth.

Next, we have workmanship. Section 110-12 of the NEC requires that electrical work be performed in a neat and workmanlike manner. There are so many different types of construction that it is difficult to give any precise instructions on how to do a neat and workmanlike job. This is where the experienced electrician has to judge for himself on how to make the job look neat. For some jobs this would require that the grounding conductor be concealed inside the residence or office. This can be accomplished in some cases by installing it behind mop boards in grooves, by fishing inside of walls to a hole drilled in the receptacle box, and by stapling along basement trusses. But each installation must be evaluated in the field to insure that the completed job is neat and workmanlike and meets the customer's satisfaction.

There is one question that remains. We titled this article, "How to Ground a Nongrounding-Type Receptacle." But we really didn't tell you how to do that. Anyone knows you can't ground a nongrounding-type receptacle.

If you are not up to doing all this work, there are provisons in the the 1996 National Electrical Code for simply replacing a nongrounding-type receptacle with a GFCI type receptacle that provides additional safety. To see how to do this go the 1996 NEC change illustration by clicking here. You will have to use your back button to get back to here.

© 1996 Gerald Newton. All rights reserved.