# 1920’s era receptacle?



## LGLS (Nov 10, 2007)

The only thing that comes close to what you describe I remember an early "tamperproof" receptacle where there were circular spring loaded rotating slotted disks in front of the actual receptacle slots, and you inserted the plug vertically to enter the disc, turn it 90 degrees to match the actual receptacle slots, and pushed it in. But that had nothing to do with the holes on the tips of the plug blades.


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## Quickservice (Apr 23, 2020)

If you were to break open one of those old receptacles you would see that the blades have tabs on them that snap into the holes of those old male attachment caps. Probably done because the blade tension was not that great back then. 

Speaking of receptacle blade tension, I got a call once from a nursing home manager who said that his residents could not plug and unplug their devices because the receptacle blades were too tight. Come to find out the original electrician had installed Hubbell 5262's... better suited for industrial use.


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## wcord (Jan 23, 2011)

Quickservice said:


> If you were to break open one of those old receptacles you would see that the blades have tabs on them that snap into the holes of those old male attachment caps. Probably done because the blade tension was not that great back then. Speaking of receptacle blade tension, I got a call once from a nursing home manager who said that his residents could not plug and unplug their devices because of the receptacle blades were too tight. Come to find out the original electrician had installed Hubbell 5262's... better suited for industrial use.


Around here 5262s are standard spec for most commercial projects


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## Quickservice (Apr 23, 2020)

wcord said:


> Around here 5262s are standard spec for most commercial projects


Wow... 5262's and 5362's are the top dogs around here. The spec here is CR15's and CR20's (Which have basically replaced the 5252's and 5242's) for commercial projects.


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## mofos be cray (Nov 14, 2016)

I think the hole on the prongs is for a lock, no?


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## VELOCI3 (Aug 15, 2019)

I think it had to do with early plug blade design that would have an indent in the receptacle tong (tang whatever) maintaining a better grip. 

I seem to recall the original plug patent had cutouts for this in the sides of the blade. The circular cutouts were done to avoid patent issues. 


Sent from my iPhone using Tapatalk


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## Quickservice (Apr 23, 2020)

VELOCI3 said:


> I think it had to do with early plug blade design that would have an indent in the receptacle tong (tang whatever) maintaining a better grip.
> 
> I seem to recall the original plug patent had cutouts for this in the sides of the blade. The circular cutouts were done to avoid patent issues.
> 
> ...


Perfect... Combine this with post #3 and the OP has the answer he was looking for.


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## wcord (Jan 23, 2011)

Out of curiosity, I ripped open a residential grade and a CR15 receptacle to see if the receptacles of today have dimples on the tong.
Nope. But the CR15 metal is twice as heavy and larger than the residential grade..
Interestingly, the CR15 metal portion is configured so the one part can be used either 120 or 240, depending on the plastic face plate


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## Metersocket648 (Feb 8, 2021)

The holes are there so if your kids like to stay up and watch TV, play games or are grounded, you can put a small masterlock so they can't plug it in


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## Quickservice (Apr 23, 2020)

Metersocket648 said:


> The holes are there so if your kids like to stay up and watch TV, play games or are grounded, you can put a small masterlock so they can't plug it in


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## Kevin (Feb 14, 2017)

mofos be cray said:


> I think the hole on the prongs is for a lock, no?





Metersocket648 said:


> The holes are there so if your wife pisses you off kids like to stay up and watch TV, play games or are grounded, you can put a small masterlock so they can't plug it in











Remember, LOTO, Safety First!


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## Metersocket648 (Feb 8, 2021)

Kevin said:


> View attachment 153893
> 
> Remember, LOTO, Safety First!
> 
> ...


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## Quickservice (Apr 23, 2020)

Fiancee???... The "being pissed at you" part is just beginning!  Check out the "Funny Memes about Marriage" thread.


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## LGLS (Nov 10, 2007)

Kevin said:


> View attachment 153893
> 
> Remember, LOTO, Safety First!


My daughter has the same back massager!


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## JRaef (Mar 23, 2009)

I took a tour of the Hubbell factory in Bridgeport CT back in the late 70s (when they were still manufacturing wiring devices here). If you didn’t know, Harvey Hubbell is the one who invented the original 2 prong plug and the receptacle for it. 

The holes were for detents in the older versions of receptacles, back when the ability to make spring tension bronze devices was limited and variations in the manual manufacturing process meant more margin of error on the assemblies of the receptacles. In the original, the bronze tabs had a spring steel clip behind them, with little protrusions that stuck through slots in the tabs to keep them in place. The holes in the plug tangs were meant to line up with those same protrusions when the plug was fully inserted. 

By playing with the bronze alloys used in making the parts and better precision via automation, that is no longer necessary. But the people who make the plugs, having no idea whether you are going to plug it into a new receptacle or an old one, often still put the holes in.


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## wcord (Jan 23, 2011)

LawnGuyLandSparky said:


> My daughter has the same back massager!


TMI lol


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## cuba_pete (Dec 8, 2011)

JRaef said:


> I took a tour of the Hubbell factory in Bridgeport CT back in the late 70s (when they were still manufacturing wiring devices here). If you didn’t know, Harvey Hubbell is the one who invented the original 2 prong plug and the receptacle for it.
> 
> The holes were for detents in the older versions of receptacles, back when the ability to make spring tension bronze devices was limited and variations in the manual manufacturing process meant more margin of error on the assemblies of the receptacles. In the original, the bronze tabs had a spring steel clip behind them, with little protrusions that stuck through slots in the tabs to keep them in place. The holes in the plug tangs were meant to line up with those same protrusions when the plug was fully inserted.
> 
> By playing with the bronze alloys used in making the parts and better precision via automation, that is no longer necessary. But the people who make the plugs, having no idea whether you are going to plug it into a new receptacle or an old one, often still put the holes in.


That's what the guy in the video covered, about Hubbell and detents and all.

I am looking for the receptacle that actually held the plug in place so well one couldn't yank it out. I pulled the cord right out of a molded plug once on the receptacle I'm thinking of (which kind of defeated the safety aspect a bit.) It must have had pins that engaged upon turning the inserted plug clockwise.

I guess I could have mentioned that this was a (lighthouse) lightkeeper's home. It may have had different receptacles than were common commercially (?), but not sure since this was around the 20's and about 50 years before my time.


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## gottspeed (Mar 8, 2010)

I’ve seen extension cords that use the holes to lock the plug in.


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## JMW (Dec 24, 2009)

I believe what you are referring to is the Hubbell “Twist-Tite” receptacle.


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## JMW (Dec 24, 2009)

It looks as if these had an exclusive polarized plug. Problem is that these seem to accept standard polarized plugs inserted in either direction. Probably why they didn’t seem to last (aside from it not being grounded). Attached are pics of a plug inserted then twisted tight. Insert the plug at an slight angle then twist slightly clockwise and it has a super strong grip.


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## cuba_pete (Dec 8, 2011)

That's got to be what I was looking for...thank you.


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