Vintage electrical outlets

[mrboilwash]

As far as I know the fist plugs have been simply screwed into a light fixture.
I have still seen quite a few Nema 1-15 (those without a grounding hole) in the States.
But I have never seen a non-polarized one.
Even my old voltage transformer from the 1950s has polarized US 2 prong outlets.
Grounding regulations apparenly don`t have to be as strict as in a 220 Volt nation, of course.
I have read in this forum about old 220V 3 prong dryer plugs that have two hot legs and share one wire for neutral and grounding.

So I wonder if the polarized 120 Volt 2 prong plugs and outlets have ever been used for grounding purposes, too ?
Maybe before the 3 prong 120 Volt outlets became common ?
Or is the idea behind just to make sure that the switch always cuts off the phase but not the neutral ?

 

[sudsmaster]

Actually, the neutral wire in a US 220 volt is not exactly shared. The full 220 volts comes from the two hot wires - each is 110 volts, 180 degrees out of phase with each other. From that, you get 220 volts AC. You could get that without a neutral, but the neutral must be used if you want to tap 110 volts off either leg. Not sure if it's ok to tap 110 volts off each leg at the same time - I would think not.

There are older extension cords that have non-polarized outlets. I have a bunch of older electrical stuff in my shed and I'll have to look see if there are any non-polarized outlets in there. I don't recall seeing any, ever, but I've seen plenty of non-polarized outlet multiplier adapters, which are a real pain if you're looking to plug a polarized plug into them.

 

[toggleswitch]

Not sure if it's ok to tap 110 volts off each leg at the same time - I would think not.
It is perfectly safe to to so (for two circuits to share a neutral) when the hots are, as stated, 180* out-of-phase.

This is actually done frequently in US kitchens when a 12/3 cable (American Wire Gauge #12/3 conductors + ground) is split to run two adjacnet 20a 110v duplex outlets (a quad) with one cable containing three wires.

Actually when this three wire arrangement is in use, and is perfectly balanced (i.e. identical wattage draw) the neutral is not needed; the two circuits are effectively in series splitting 220v, with each circuit receiving 110v. When slightly unbalanced, the neutral comes into play.

In the beginning of "things electrical" neutals were fused and switched which was found to be dangerous. If the neutral fuse blew the line would appear to be dead; until current found a ground/earth. Sadly this would sometimes happen through a person.

I don't think on 110v circuits the neutral and the ground are intended to be shared at the outlet/power-point.

I'm not sure when grounding became thought of as necessary.

 

[westytoploader]

About 4 years ago there was an estate sale at a house down the street from me, built in 1961 I believe and in pretty much original condition. ALL of the outlets were 2-prong, not one grounded one in sight. Not even in the bathrooms either!

And if I remember correctly, I think we even had a 2-prong or two here, although the majority of the outlets were grounded. However, there were still no GFIs in the bathrooms until we changed them out.

 

[westytoploader]

This house was built in 1967, BTW.

 

[58limited]

My house was built in 1941. It still had many original outlets when I bought it. They are made of ceramic and are polarized, not grounded. I have been replacing these as I've remodeled each room. One thing that was a pain: the previous occupants repainted all the rooms before selling it. They painted over EVERY outlet and switch. Half-assed job - too lazy to remove the switch plates and cut in. I had to chip paint out of outlets to plug things in and pry the outlet and switch plates loose from the walls. This, and painting over door/cabinet hinges are two of my pet peeves when it comes to remodeling.

 

[sudsmaster]

Toggle,

Sorry if I didn't state it more clearly. What I meant was I'm not sure it's ok to have both hot legs providing 110 volts to neutral in the same appliance.

Of course 220 legs are split to provide separate circuits in a home or business. But those are separate circuits, each protected by a fuse or circuit breaker, not all in one electrical device.

As I understand it, there may be some concerns about splitting 110 off a 220 volt circuit in an appliance if at the same time that 110 volt leg is not provided with overload protection. And of course balancing the load for the entire home is important as well.

 

[toggleswitch]

Ah inetereting. When I worked for Sears selling appliances I heard this:

Sears went back to Whirlpool an said:
Give us the 110v functions off of ONE hot leg in an electric range/stove/cooker/oven/cooktop.

Reason: To be able to stick a standard flex plug-and-cord on it in a store when displayed so that it will do everything except heat-up the elements.

 

[rp2813]

I'll have to check my stash of old electrical stuff and also check some of the old and possibly original or re-used outlets at my mom's place, which was built in 1926. Having gone through the depression, my parents never threw anything out and my dad re-used a lot of stuff, so there are old receptacles in the basement that he used when installing outlets down there, etc.

From what I've read here, it seems the receptacles have always been designed to take a polarized plug, but the plugs themselves haven't always been polarized. I know you can buy certain electrical items today that still don't have a polarized plug on them, and it seems most vintage electrical stuff doesn't have a polarized plug. I still don't know what polarizing accomplishes.

I have some of those screw-into-a-lightbulb-socket type outlets that are super old and they're not polarized. Assuming that might have something to do with the socket arrangement not accomodating polarization, but I have no electrician background so that's just a guess.

 

[toggleswitch]

You gotta stick your finger all the way in to get jolted.

~I still don't know what polarizing accomplishes.
It is intended to keep the hot as hot and the neutral as neutral.

~Assuming that might have something to do with the socket arrangement not accomodating polarization.
I disagree! In a standard (US) Edison-base lamp holder, the shell is wired to be neutal and the base is hot, for safety.

 

[brisnat81]

Jetcone gave me a good example of why polarisation is import

When I was over in the US, Jon explained why he always replaces the cords on his washers.

On a 1950's bendix, if you plug the non polarised plug in the wrong way around, you get lots and lots of live metal bits all over the machine.

Dont ask me how, but I assume it must have something to do with the bonding of the neutral to earth.

 

[mrboilwash]

Is there a chance to see a picture of one of the 1926 outlets ? Would be great if possible. Early electrical stuff is just as fascinating as applinaces.

I also wondered why I have never seen a really vintage polarized plug as there are so many early polarized outlets.

I assume the reason for polarization is to make sure that the hot leg is certainly turned off. For example to make sure that there is no voltage on the element of a toaster when switched off but still plugged in. That would make sense.
I could also imagine that polarization was originally meant to use the neutral wire for grounding purposes, as well.
The idea might have been dumped again because of safety concerns and replaced with the three prong system. I am only thinking out loud and assuming what could have been the case.
No elecricians among us to clear it up ?

 

[sudsmaster]

I *think* I've seen old porcelain overhead light fixtures, the type with a single outlet on their base, and as I recall the outlet may not be polarized. But I don't have one handy to check this.

When I was a teen we lived in a number of older flats in SF and I'm trying to remember if any of them had non-polarized outlets. Certainly none of them had third ground prongs!

 

[Cybrvanr]

The worst of it is when you get into an older home that someone has upgraded the outlets in, but doesn't understand the way that third prong works!

When I moved into my home, the previous owners thought they were doing good by replacing all the outlets with 3 prong grounded plugs, and installing GFI's in the kitchen & bathrooms. Only problem was that the house was wired with 12/2! There was not ground line in the romex, so the third prong was useless. You couldn't trip a GFI if you tried!!!! I found out about this when I noticed I was getting hum and noise in my stereo equiment because the ground was lifted. Modern A/V gear likes to be earth grounded to minimize noise and distortion. A $5 plug tester from Lowe's revealed the problem. Slowly but surely, I'm re-wiring the entire house with 12/3 to make it compliant. I started with the kitchen & bathroom circuits.

According to an electrician I know, you must keep the 2 prong outlets installed unless you have a legitimite ground to connect behind the outlet!

 

[58limited]

My house is wired with 12/2, but all of the original wiring is in metal conduit and the conduit has been grounded, so the third prong can ground through the conduit. I plan to upgrade the wiring, however, so that it meets modern codes. Already have all the wire and brakers, just need time.

 

[rp2813]

Stefan, I'm not so sure any of the outlets at my mom's place actually date back to 1926. There are a couple of old ones, but probably nothing you haven't already seen.

Suds, I think your description of porcelain single light bulb fixtures with built-in outlet reinforces my theory about the screw-in outlets. Since in most homes the lights are on their own circuit, I wonder if polarization matters where hard wired light fixtures are concerned?

 

[brisnat81]

Ralph, see Steve/Toggleswitches response above regarding polarity and light sockets.

The polarity is important, because it is much harder to accidentally touch the live part.

Also, when the Hot line is switched, off is off, and its safe if you accidentally touch the socket.

 

[coldspot]

On this page is a photo of a old usa wall screw in plug.

http://www.oldchristmaslights.com/1900_1920.htm

 

[sudsmaster]

Cybrvanr,

Actually, a ground is not needed for a GFCI outlet to work perfectly well. The device functions by measuring the amount of current on the hot and neutral wires - it ignores the ground. If there is an imbalance between the amount of current on each wire, then it will trip the breaker and cut off power.

But yes, it is against code to install three prong grounded outlets where there is no ground. However, many people (including myself) do it in limited situations. In my case, the old outlets in the older part of the home (about three rooms) were so worn that they couldn't hold a two prong plug properly. Rather than go hunt around for new two-prong outlets, I installed three prong grounded ones, with a mind to go back and add a ground wire later. Well, it'a but 10 years later and I still haven't added the ground wire . It's not ideal, and would have to be addressed if ever I were to sell the place, but for now it's just me and I know what the limitations are and it doesn't bother me at all. Fortunately aside from one older bath, the ungrounded circuits are pretty much limited to rooms without major appliances or plumbing.

I have however added GFCI outlets to protect against accidental electrocution in the kitchen, baths, and outdoor outlets. In only one case is the wiring old 2 wire ungrounded, but the GFCI works perfectly well (I tested it safely ;-))