Grounding a 2-prong laundry receptacle

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JDBrown

Senior Member
Location
California
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Electrical Engineer
Most of my experience is with Commercial projects, but recently I've been getting asked for advice about residential remodels -- particularly the issue of replacing 2-prong receptacles with 3-prong receptacles. Most of the cases I've been consulted about have been pretty straightforward: we usually just have the Electrician replace the first receptacle in the circuit with a GFCI and label each receptacle on the circuit according to NEC 406.3(D)(3)(b) and (c), and tell the homeowner not to plug a surge protector into any of those receptacles since it won't work properly. This hasn't been much of an issue, since the receptacles have usually been located where all that's going to be plugged into them is a lamp or a fan anyway.


Which brings me to the latest installation we're working on. This house is one of those that has been added onto several times over the years. The receptacle in question is in the laundry room, but it was originally an exterior receptacle so I doubt it's on its own dedicated laundry circuit. It's one of those old school receptacles with three 2-prong outlets in one single-gang device, and the homeowner has his washer and gas dryer plugged into it using 3-to-2 prong adapters. There is also a surface-mounted 3-wire dryer receptacle in the same area, which is fed via 1/2" EMT.


As far as I can tell, we have the following options:
1. Run a new dedicated laundry circuit.
2. Verify the grounding path of the existing 1/2" EMT feeding the dryer receptacle, and connect an EGC from the EMT to the 2-prong receptacle below. Perhaps the Electrician could put a box extension on the 2-prong receptacle and route a bit more EMT down to the box extension. Then he could attach an EGC to the ground screw in the box. I believe this would comply with NEC 250.130(C).
3. Do the same as option #2 above, but pull a new EGC through the existing conduit all the way back to the panel instead of using the EMT as the grounding path. This should also comply with NEC 250.130(C).
4. Replace the 2-prong receptacle with a GFCI and label it according to NEC 406.3(D)(3)(b).


Knowing this particular homeowner, he's not going to like the idea of tearing up his exterior wall to pull a new circuit, so that leaves me with options 2, 3 and 4. I'm inclined to tell the Electrician to just replace the existing receptacle with a GFCI and be done with it, but I'd like to hear your opinions on it, especially if you know of any potential dangers of using a GFCI with no EGC for a washer and dryer. I think it would be safe, but I've got this nagging feeling that I'm missing something... Any thoughts or suggestions you have would be much appreciated.
 

GoldDigger

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Location
Placerville, CA, USA
Occupation
Retired PV System Designer
... but I'd like to hear your opinions on it, especially if you know of any potential dangers of using a GFCI with no EGC for a washer and [gas] dryer. I think it would be safe, but I've got this nagging feeling that I'm missing something... Any thoughts or suggestions you have would be much appreciated.
The GFCI receptacle will prevent any shock hazard from faults in the washer or dryer. But some appliances like washers, particularly older models, might trip a GFCI receptacle or a GFCI breaker.
If there is no problem with that nuisance tripping, then 4 is all that is required by the NEC and avoids all sorts of other potential issues.
However, it will not provide protection against a fault somewhere else that might end up energizing the metal parts of the washer or dryer.
Rather than trying to provide a ground for the receptacle from somewhere else as in 2, running a bonding wire directly from the washer to an official ground bonding point would possibly be OK. If the manufacturer's instructions for the appliances require a three wire connection, then you will have to provide that or unplug them. :)

Adding a new receptacle box or adding a ground to the existing receptacle box through the wiring and conduit to the unused dryer outlet might trigger a requirement to pull an EGC for the dryer circuit anyway (if the grounding path of the existing wiring cannot be inspected or tested for adequacy and properly bonded to provide the EGC.)
 
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