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Replacing 2 prong receptacles |
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Fig.101
Test from hot to metal box- no ground |
Fig.102
Okay to replace in kind if present code does not require GFCI at the location. |
Fig.103
Okay to replace with GFCI. Attach label "No equipment ground". |
Fig.104
Okay to run equipment ground from box to grounding electrode system or equipment bus in panel feeding ciruit. |
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2002 NEC Code Section->
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406.3(D)3a
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406.3(D)3c
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250.130(C)
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Fig.105
Test from hot to metal box- box grounded. |
Fig.106
Install equipment bonding jumper from receptacle to box. |
Fig.107
Install "self-grounding" receptacle. |
Fig.108
Install GFCI with equipment bonding jumper from receptacle to box. |
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2002 NEC Code Section->
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250.146
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250.146(B)
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406.3(D)2
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Subject: Converting two-prong outlets to three-prong
Date: Thu, 16 Oct 1997 18:28:28 -0700
From:
Redwood Kardon <redwood@codecheck.com>
Robert S. Huss wrote:
>
> We recently bought a 40 year old house, and most of the outlets are
two-prong outlets. On the few things we have that need a three-prong, we've
used a converter screwed to the grounding screw of the outlet. I'd like
to replace these outlets, but I'm not sure if we need to have an extra wire
for the three-prong outlets. Is there a wire attached to the grounding screw
that I can attach to the third hole instead?
Bob Huss
Your house is of a vintage that might or might not have an equipment
grounding system.
Determine if your metal boxes are grounded.With power off check for continuity between box and neutral. If there is continuity than box is grounded. If the boxes are fed by metal sheathed cable(commonly called BX but refered to in the Code as AC, Armor Clad cable) then you probably have a grounded box.
Option 1- metal boxes grounded.
- Install a "self-grounding" outlet.
- Or install a ground clip that snaps on the edge of the box and provides a connection for an equipment grounding wire to the green screw of a typical 3 prong outlet.
- Or if there is a threaded 8/32 hole in the back wall of the box connect with a green pigtail(8" of green wire with 8/32 green screw).
Option 2- metal boxes no ground. See: Illustration
Option 3- plastic or bakelite box fed by a two wire cloth covered romex. No ground. See: Illustration
Option 4- any box no ground. It is permitted to replace it with a ground-fault circuit-interrupter-type of receptacle(s).
- 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.
- These receptacles shall be marked "No Equipment Ground."
NEC 210-7. ...(d) Replacements. Replacement of receptacles shall comply with (1), (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 the 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, or c below:
a. A nongrounding-type receptacle(s) shall be permitted to be replaced with another nongrounding-type receptacle(s).
b. A nongrounding-type receptacle(s) 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 nongrounding-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.
NEC 250-50 ...Exception for (a) and (b): 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 Section 250-81, or to any accessible point on the grounding electrode conductor.
NEC Handbook Due to changes in Section 250-81 made in the 1993Code, an interior metal water pipe more than 5 ft from the point of entrance of the water pipe into the building is no longer allowed to serve as a conductor. This revision was due to the increasing use of nonmetallic piping and fittings.
Check ©1998 by Redwood Kardon
