Ungrounded Outlets

[Chetlaham]

I'm curious if anyone still has these in their home. How do you feel about them? Do you ever find them incompatible with a random plug? Do you have any pictures that you can share?

I personally have an embarrassing soft spot for the nostalgic look, however, that is no excuse to skip on safety. Its interesting to think though, if everything was double insulated these might still be around in many newer homes today.

 

[pulltostart]

Most of the houses that I've owned have been built about 1957, and typically do not have grounded branch circuits.  When I've painted and worked on the houses, I've always installed new 2-prong outlets in the old wiring.  In cases where newer wiring has been installed for additional circuits and they include a ground wire, I install the grounded outlets.  The current house was built in 1976 and all branch circuits are grounded, which is nice; however, there is a fair amount of aluminum wiring in the house so I have to be sure how the device is wired before I buy a new outlet or switch.

 

I have been told previously that it's illegal to replace an ungrounded device with a grounded one if the wiring doesn't include a ground wire.  This would probably be applicable when the house is sold and if the buyer is misled into thinking the house has 3-wire service throughout, only to find out later that that isn't the case.

 

lawrence

 

[joeekaitis]

Grew up in a house with 2-prongers.

 

The only grounded outlet was the 220V in the garage for the dryer.  The house was probably refitted to bring the outlets up to code after my parents passed away and we sold it.  It's a Levittown-inspired rancher (single story).

 

The house Cathy and I live in always had 3-prong outlets.  We added a 220V in the kitchen when we went from a gas stove to induction.  Both are in Rialto, CA.

 

 

[qsd-dan]

The only grounded outlet was the 220V

It was a 4 prong receptacle? I doubt that unless it was upgraded later on.

 

My grandparents lived in a house built in '63 that had 2 prong outlets. Never problem in the 40 years they lived there.

 

[Chetlaham]

You can replace an ungrounded with receptacle with a grounding one provided that you protect the circuit with a GFCIs and install those stickers that come with the box saying "GFCI protected" / "no equipment ground".

Joe, I'm curious as well, was the receptacle three prong or four prong?

Some parts of the world like the Philippines still install ungrounded receptacles in residential.

 

[Marky_Mark]

A 240-Volt electric dryer outlet in the US is always grounded, otherwise the dryer wouldn't work.  

 

They used to have a shared neutral-ground wire and used a 3-prong plug.  This wire is required, otherwise the motor, timer, lights etc., wouldn't work as they need 120 V.  The frame of the appliance is supposed to be connected to this neutral-ground wire.

 

Since about 1998 they have used a 4-prong plug with a separate neutral and ground.

 

[qsd-dan]

A 240-Volt electric dryer outlet in the US is always grounded, otherwise the dryer wouldn't work.  

 

 

In a 3 prong 240V design, everything is copasetic until a situation like a motor becomes "unbalanced" through use and more current flows through one hot prong than the other. The difference between the 2 flows through neutral becomes a live wire. Since both the neutral and ground wire are connected to the dryer cabinet, the surface of the dryer is now conducting electricity. It's a pretty rare occurrence but evidently happened enough in the past to mandate a 4 prong design in 1996.

 

[cfz2882]

My 1952 house has a few of those outlets still.Breaker box was upgraded in 1980 when some extra circuits were added.

 

[Chetlaham]

<blockquote>
A 240-Volt electric dryer outlet in the US is always grounded, otherwise the dryer wouldn't work.

 

 

</blockquote>
Correct, the outlet has a grounded conductor but not a grounding conductor. Its a technicality which results in NEMA 10-30 and NEMA 10-50 receptacles being classified as "none grounding" types. 3 pole, 3 wire:

 

 

https://i.pinimg.com/originals/11/80/d5/1180d5617608781e99ad1a6e78288664.jpg
 

 

https://www.ebay.com/itm/3633426887...QkHDa9kgSKmbkpYsyoKmReg2qKE9llKo5mADe2h-7btRI
 

 

Where as 6-30r and 6-50r are grounding types despite not having a neutral (2 pole 3wire).  Modern NEMA 14-30r and NEMA 14-50r with a neutral and ground (3 pole 4 wire) classified as grounding types.

 

Code makes a distinction between a ground<span style="text-decoration: underline;">ing</span> and ground<span style="text-decoration: underline;">ed</span> conductors even though in that past it was an inadvertently common

error to treat them interchangeably. Ie, you could ground a dryer through a neutral wire but you could not use the bare grounding wire in NM-B cable as the neutral.

 

[this post was last edited: 4/4/2023-13:59]

 

[Chetlaham]

Neutral Becoming Live

Yup! That was the big reason. Normally the the motor on a clothes dryer pulls roughly 5 amps.

 

 

10 gauge copper has a resistance of about 1.2 ohms per 1000 feet. So a reasonable worse case 100 foot home run would be 0.12 ohms. VD= IxR; would mean 5 amps  x 0.12 ohms = 0.6 volts on the frame of the dryer relative to other grounded objects like the cement floor or the washer. Typically 0.6 volts isn't even perceivable, so no harm in connecting the neutral to the frame.

 

That is until the neutral breaks, becomes loose underneath a screw, poor contacts in the receptacle, ect... then the frame of the dryers rises to 120 volts... One hand on the dryer, one on the washer, damp hands lowering skin resistivity... one does not have to imagine why the practice was deemed risky in modern times. 

 

 

For those over seas, here is the wiring diagram relevant to a US dryer-

 

3 wire:

 

 

https://i.stack.imgur.com/oYHa7.jpg
 

 

4 wire:

 

https://i.stack.imgur.com/xB3g0.jpg

 

[Marky_Mark]

True.  I knew I wasn't being very accurate when I said the wire was a combined neutral-ground, as it is technically a neutral wire (grounded conductor) that is also used to ground the dryer's frame.  

 

I think the reason it was changed is that just one single fault could cause the dryer's frame to become live, therefore able to deliver a fatal electric shock.  This would happen if the neutral wire broke at some point along the circuit. 

 

With the 4-prong design, I think you would need two simultaneous faults to cause this, i.e. first a break in the ground wire AND then another fault causing the live wire to contact the frame.

 

As for the ungrounded two-prong outlets of yesteryear, I think I may have seen these once or twice in older mid-century homes in Palm Springs, but even then it's only been the odd one or two.  I have certainly seen them for sale at Home Depot.  Yes they are kind of cool, if they are original to the house.  I like that!

 

[Chetlaham]

Technically you would be correct in the UK

To be fair, Under IEC / BS7671 standards the neutral conductor in the same Edison circuit if replicated outside the US would be classified as a PEN conductor, Protective Earth Neutral, and thus you would be correct in calling it a combined neutral-ground.

 

The NEC however requires it be treated it as a grounded conductor, that only by special exceptions given in the code, can ground the frame of the range or dryer.

 

In Eastern Europe it was common to have TN-C up to the sockets. You would only have two wires, Live and PEN, and the PEN conductor would land on the earth terminal and then jumper to the neutral terminal. Today this is forbidden, a hold over practice from the days of the soviet union.

 

 

https://www.asutpp.com/tn-c-earthing-system.html
 

 

You are correct, you'd need at least 2 failures, and with the recent code changes you'd need 3 failures. Code now requires most US dryers to be GFCI protected. The idea is that if you lost the equipment grounding conductor with a simultaneous insulation break down the GFCI would act as a last resort and trip.

 

 

https://www.electricallicenserenewa...ation-Courses/NEC-Content.php?sectionID=808.0
 

 

I think, that as time goes on all circuits in the US will require some form GFCI or GFP protection regardless of voltage, wiring method, rating, or equipment installed. Equipment grounding conductors can and do become compromised in a world where newer standards of safety dictate that multiple things must go wrong first before any danger becomes present. 

 

[sudsmaster]

I guess I am lucky here because this 1941 house was remodeled sometime in the 1960's or 70's. At that time one of the bedrooms (2) was converted to a family room, with a washer dryer closet,  and another bedroom was added to the rear of the home, with its own bath. All the 120 outlets in the main house and other structures are three prong, grounded.

 

However, perhaps this was all done before four prong 240 volt plugs became the standard, because the plug for the original 240 volt dryer (which I soon replaced with a gas version), and all the rest of the 240 volt plugs, such as in the separate workshop (1,000  + sq ft) are all three prong. Never had a problem with any of those. I have seen four prong outlets and plugs at places like Home Depot, and always wondered what if anything they added. Now I know, so thanks.

 

[circlew]

My house was built in 1952, and all original 120 volt receptacles were 2 prong. As the years went on, a few new circuits were added, with the 3 prong grounding type installed. When I started the renovation, I removed all the existing wiring except for an abandoned circuit in the one room where I didn't remove the wall surface. Therefore, I have one 2 prong receptacle left in the house, though not in service. I plan to do some work in there, and it will be replaced with a new receptacle and cable.

As to 240 volt 4 wire receptacles for ranges and dryers, this is required because some parts of those appliances operate at 120 volts. That would be lights on a range, and older models used 120 for low heat settings. Dryer motors operate at 120 volts. If the appliance operates solely on 240 volts, such as an air conditioner or heater, the cord and plug are only 3 wire.

While the code started requiring 4 wire circuits for all new 120/240 installations in the 90's, it was required many years earlier in certain circumstances. One of these was in mobile homes, and another was any 120/240 volt circuit originating in a panelboard OTHER than the MAIN SERVICE ENTRANCE. The high school I attended, which was built in 1966, had 4 prong receptacles for all the ranges and dryers in the home-ec room. Other places they were found was in commercial buildings and large homes that had numerous panelboards throughout the building.

 

[fan-of-fans]

They are kind of neat to see. That said, I would probably avoid buying a home with ungrounded wiring since a lot of appliances these days have grounded cords, not just things like washers and refrigerators.

And surge protectors won’t work properly without a ground.

On a side note, I don’t like how replacement 2 prong outlets from both Eaton and Leviton don’t have the slots centered in the circles anymore. These days they look like a 3 prong that’s had the ground hole filled in, the slots are offset and it looks silly.

 

[circlew]

Another thing is that all 2 prong receptacles sold today that I'm aware of are the cheap residential grade. I've not seen any specification or commercial grade receptacles that aren't the grounding type in many years. Residential grade devices have no place in a premium grade wiring system.

 

[Chetlaham]

I know what you mean about the replacements. Leviton and Eaton are no longer centered and I'm not sure about the others. Really makes me upset. Do you know about the other brands?

 

[daveamkrayoguy]

The house I grew up in has had and still has to this day, ungrounded two-prong outlets which supposedly a three prong adapter could safely ground, in use of heavy duty appliances such as refrigerators and washers as well as supposrting electrical implements on gas dryers and gas stoves...

So far I haven't seen one outlet become replaced by anything three prong, except in the house I live in now having been built years later has three prongs, all grounded, but maybe meaning that the side of town I live in just conforms to updating to modern standards, versus my o.d neighborhood not being such except in the case of renouvations a number of homes with exception of that last remnant of being upgraded and updated to...

Lastly, in terms of safety, we'd never encountered anything where such renewal was ever mandated due to any unsafe electrical mishaps--there weren't ever any...

-- Dave

 

[Chetlaham]

Code only requires upgrades if a device is replaced, or more commonly if the wiring is being extended/upgraded to a significant degree. The rest is considered grandfathered, so, it can legally remain for the rest of eternity. Fuse panels and knob and tube are nowhere near as bad as people make them out to be, provided they've not been illegally tampered with.

 

 

In some ways it would be kind of cool if everything in homes were double insulated- no way anything could ever become live. Two wires at the service head, 2 pole breakers, 230 volt appliances.  Here is such a main panel being made up in the Philippines: 

 

 

 



 

 

Like Japan they us two wire romex through out the home, and 3 wire romex for the 3 way switching. I think blue and yellow would make good vibrant contrasting colors here in the states- with blue, yellow and red for the 3 wire romex.