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#12824 - 08/18/02 04:19 AM Male attachment plug prongs
jes Offline
Member
Registered: 07/12/02
Posts: 103
Loc: CT
OK, here's a trivia question.
Why do male attachment plug prongs (some, not all) have round holes through them near the ends??? I DON'T know the answer!!
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#12825 - 08/18/02 05:04 AM Re: Male attachment plug prongs
walrus Offline
Member
Registered: 07/25/02
Posts: 680
Loc: Bangor Me. USA
Lockout, tagout?
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#12826 - 08/18/02 08:34 AM Re: Male attachment plug prongs
NJwirenut Offline
Member
Registered: 09/15/01
Posts: 806
Loc: Bergen County, NJ
Helps hold the plug into the receptacle. There is a corresponding "dimple" in the contact spring, which "locks" into the hole in the plug blade.
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#12827 - 08/18/02 08:54 AM Re: Male attachment plug prongs
sparky66wv Offline
Member
Registered: 11/17/00
Posts: 2232
Loc: West Virginia
And here I thought they were to clean the contacts...?

Makes sense though...
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#12828 - 08/18/02 01:33 PM Re: Male attachment plug prongs
pauluk Offline
Member
Registered: 08/11/01
Posts: 7520
Loc: Norfolk, England
Don't forget that the holes also make it easy to wrap bare wires for Mexican-style extension cords....
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#12829 - 08/18/02 04:45 PM Re: Male attachment plug prongs
jes Offline
Member
Registered: 07/12/02
Posts: 103
Loc: CT
Interesting comments but:
The holes have been there a LONG time... long before lockout/tagout came on the scene, however I have seen some loto devices that use the holes.
The contact idea is interesting but I've never seen a receptacle with contact strips having dimples...
A cleaning function is interesting...could be!
Still searching!
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#12830 - 08/18/02 06:53 PM Re: Male attachment plug prongs
Anonymous
Unregistered

I was told back in school that a long time ago receptacles had little spring loaded balls that would engage those holes.
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#12831 - 08/19/02 04:48 AM Re: Male attachment plug prongs
Trainwire Offline
Member
Registered: 03/15/02
Posts: 360
Loc: Strasburg,PA,USA
My bet is that they are part of the manufacturing process, like maybe how they are hung onto when they mold the plug around them.
Trainwire
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#12832 - 08/19/02 05:05 AM Re: Male attachment plug prongs
Texas_Ranger Offline
Member
Registered: 12/17/01
Posts: 2391
Loc: Vienna, Austria
I've got a 1970ies Sony stereo with NEMA plug and an unswitched outlet. When I push in a plug I can feel that the prongs get locked when fully inserted.
BTW, I was close to using the mexican style cord. I replaced a light switch in a room without a window, so I needed some temporary lighting. The only thing I could find was an imported US table lamp with an adaptor which has been hooked up forever in our living room. When I tried to hook it up I nearly got a fit. The adaptor was as stone aged as the lamp and it wouldn't fit Schuko receptacles! Finally I pulled two (illegal) ungrounded extension cords through the appartment and hooked my lamp up. SO much about being able to stick to codes...
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#12833 - 12/04/06 02:13 AM Re: Male attachment plug prongs
Luketrician Offline
Member
Registered: 07/08/06
Posts: 272
Loc: Sale Creek, TN USA
Quote:
Don't forget that the holes also make it easy to wrap bare wires for Mexican-style extension cords....


I'm not an old timer on this site but I bet there are some pics of this in the violation photo forum. I've seen that practice done plenty of times, unfortunately.

Luke
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Electrical Planner for TVA.

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