Home>Discussions>ELECTRICAL & LIGHTING>Upgrading 2-prong to 3-prong in old 2-wire system
35 posts / 0 new
Last post
katonkasno
Upgrading 2-prong to 3-prong in old 2-wire system

I have a 1949 house, with 2-prong outlets and 2-wire system (no ground, even after opening the wrapping to check). All circuits are 20 amp, the panel is good. Also for safety I am checking for cracked rubber, and using shrink tube if any is exposed.

Question: I want to upgrade some or all of my outlets to a 3-prong outlet. I installed 20 amp GFCI's where I needed these per the NEC(2-wire, no ground). If I install a 20 amp GFCI on the first outlet of a circuit, and supply the remaining outlets with the LOAD side... can I install regular 15 amp 3-prong outlets for the rest in the same circuit? And label them "No Equipment Ground" and "GFI Protected"?

Thanks.

katonkasno
Re: Upgrading 2-prong to 3-prong in old 2-wire system

Thanks, I will make it happen.

Re: Upgrading 2-prong to 3-prong in old 2-wire system

would'nt those outlets need to be 2 pronged outlets even gfi protected unless there was a egc connecting them to the gfi?

katonkasno
Re: Upgrading 2-prong to 3-prong in old 2-wire system

I don't have access to the NEC code online to check that out. But, the first non-grounded 2-wire outlet will be a GFCI. The remaining outlets don't need a ground wire since there would not be anything to ground the wire to.

The GFCI will operate like this: It measures the volts/amps leaving the Hot side of the Load, and in return if the Neutral on the Load is -5v it will trip. The ground is not involved.

I am no expert, but this is how I interpreted my findings. Please confirm for me.

Ernie_Fergler
Re: Upgrading 2-prong to 3-prong in old 2-wire system
deadshort wrote:

Go read through 406.3(D)(3)

I agree, depending on the marking provided, they could be either a two prong non ground outlet section {3}{b} or a three prong grounded type in section {3}{c}. All in 406.4{D}{3}, of course.:D

Ernie_Fergler
Re: Upgrading 2-prong to 3-prong in old 2-wire system

As I read it the key is getting all your ducks in a row, ie, the proper placement of the GFCI......

JLMCDANIEL
Re: Upgrading 2-prong to 3-prong in old 2-wire system
deadshort wrote:

406.3 Ernie, 406.3........... :D

"(3) Non–Grounding-Type Receptacles. Where attachment
to an equipment grounding conductor does not exist
in the receptacle enclosure, the installation shall comply
with (D)(3)(a), (D)(3)(b), or (D)(3)(c).
(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 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 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."

While this does meet NEC and safety requirements it should be noted that it may not meet grounding requirements for some electronic equipment that have filtering to ground.
Jack

Ernie_Fergler
Re: Upgrading 2-prong to 3-prong in old 2-wire system
JLMCDANIEL wrote:

While this does meet NEC and safety requirements it should be noted that it may not meet grounding requirements for some electronic equipment that have filtering to ground.
Jack

True. But in the real world what would those issues be?
I am not getting into a flame war here, just posting that question...:)

Re: Upgrading 2-prong to 3-prong in old 2-wire system

I think theres room for improvement within the NEC here, simply reying on a sticker to tell someone there is no egc doesnt replace a ground. I understand that article thanks for clearing that up for me ernie, I'll once again fall back on the NEC NOT being a guide for electrical instalations but instead a MINIMUM stadard. Load protecting outlets without an egc isnt something I would practice, IMO I think your better served with devices that have no egc provision (2prong)

JLMCDANIEL
Re: Upgrading 2-prong to 3-prong in old 2-wire system
Ernie_Fergler wrote:

True. But in the real world what would those issues be?
I am not getting into a flame war here, just posting that question...:)

In some electronic system filters to ground are used to remove electrical noise both internally created and from external sources. For instance, the shield on a coax cable must be grounded to prevent piggybacking extraneous RF signals.
Jack

JLMCDANIEL
Re: Upgrading 2-prong to 3-prong in old 2-wire system
Lloyd wrote:

I think theres room for improvement within the NEC here, simply reying on a sticker to tell someone there is no egc doesnt replace a ground. I understand that article thanks for clearing that up for me ernie, I'll once again fall back on the NEC NOT being a guide for electrical instalations but instead a MINIMUM stadard. Load protecting outlets without an egc isnt something I would practice, IMO I think your better served with devices that have no egc provision (2prong)

Lloyd, with a GFCI installed the ECG provides little if any protection other than what I described above..
Jack

Pages

TV Listings

Find TV listings for This Old House and Ask This Old House in your area.