American 3 pin mains plug and socket

That's to make it easier to connect solid wire from the outlet box directly to the plugs when you're too cheap to buy a new receptacle.

Jeff

Jeffrey Angus wrote in news:j1h1ti$ees$ snipped-for-privacy@dont-email.me:

IIRC,a new receptacle costs less than $1 at Wal-Mart.

BTW,I've seen a lot of US power plugs with ground pins that are folded sheet brass that has the half-round/half-square,or U-shape cross- section,with a bevel at the end. Maybe cheaper to make than a solid round pin?

the holes in the flat blades are probably a leftover originally intended for some sort of detent (ball detent?)to help retain the plug.

I should have said I am in the UK Now you say that I've seen a plug with a U channel ground pin ,somewhere along the way. I could see that arrangement maybe giving some sort of sprung/ tolerating fit. But how does a cylindrical brass pin make good contact with an unsprung receptacle pin ?

The internal split wiper pairs of the AC socket are under some tension, to make a good electrical contact, this holds for the ground pin as well.

As for the holes in the flat pins, I can't find a reference easily but believe that they are for dimples in earlier sockets that are no longer present. It could also be that dimples exist in ceiling outlets only...you can do some hunting and report back!

John :-#)#

John :-#)#

All the outlets I've checked have some type of spring material on all the contacts. Some are better made than others (a receptacle with a brand I recognize versus a $1 nameless duplex receptacle at WalMart). I spent a bit more for the 20 amp receptacle that sees use with a table saw and a small wirefeed welder. The saw can hit 20 amps at startup and the welder can run near 20 amps continuously, but I rarely have the arc going for more than a 30 seconds at a time - I'm not building bridges, just welding small things such as a hanger for a garden hose or repairing a metal stand for a bird feeder.

John

I have seen, in the past, 'security' locks (both metal and plastic) that engage both the mains pins through these holes and prevent insertion into an outlet.

Probably NOT what the holes are for, but such a lock could be A Good Idea on some appliances or equipment in an environment with children.

Jonesy

"N_Cook" wrote in news:j1h6kk$h9o$ snipped-for-privacy@dont-email.me:

I think you did.

AFAIK,the receptacle female contacts are one-piece,formed from sheet stock,and the blade or ground pin goes in between the sides,spreading them apart slightly. the female contacts have some springiness built in. They are like a very deep U shape.

BTW,I checked a "hospital-grade" plug,and it's ground pin is U-shaped flat stock,as I described earlier. Pretty heavy gauge stock,around 1/16" thick.

Close - spring loaded pins with a ball-shaped end, designed to hold the blade in the outlet. As better alloys were developed the construction became much simpler, but the detents remained.

PlainBill

I came across an old bakellite 3 pin USA receptacle yesterday. The third pin socket in that was 2 definite sprung flat contacts, touching across a diameter of the pin