hole in plug ends??


Old 09-15-04, 04:15 PM
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hole in plug ends??

Can some one tell me why there are holes in all of the 120 volt plug ends on all the tools and apliances that I have looked at. Electrician and others can not give me a definite answer. Could it be for heat distribution?
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Old 09-15-04, 04:49 PM
Join Date: Sep 2002
Location: welland ontario
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My guess is it has something to do with production. The molding tools use the holes for grip or alignment.
Old 09-15-04, 05:08 PM
Join Date: Sep 2000
Location: United States
Posts: 18,497
It's simpler than that. There is a corresponding bump on the receptacle clip that fits into that hole that helps hold the plug in.
Old 09-16-04, 08:52 AM
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Join Date: Sep 2003
Location: The Colony, Texas
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John, Nothing's ever that simple...

Of course, I've got to wonder where they came up with reason #3.

From www.howstuffworks.com

There are three reasons for the holes:

If you were to take apart an outlet and look at the contact wipers that the prongs slide into, you would find that they have have bumps on them. These bumps fit into the holes so that the outlet can grip the plug’s prongs more firmly. This detenting prevents the plug from slipping out of the socket due to the weight of the plug and cord. It also improves the contact between the plug and the outlet.

Electrical devices can be "factory-sealed" or "locked-out" by the manufacturer or owner using a plastic tie or a small padlock that runs through one or both of the prong holes. Construction projects or industrial safety requirements may require this type of sealing. For example, a manufacturer might apply a plastic band through the hole and attach it to a tag that says, "You must do blah blah blah before plugging in this device." The user cannot plug in the device without removing the tag, so the user is sure to see the instructions.

There also is a small savings in raw materials (metal) for the manufacturer of the actual plug prong. Every little bit helps!
It has been reported that really old outlets used captive ball bearings and coil springs for the detent, but today it is done with a bump and springy copper contacts.

Doug M.
Old 09-16-04, 05:55 PM
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Smile grateful

Thanks for the info on the plug ends. I had thought about the lock out possibility but thought that maybe the pressure from the splines was enough. It make sense. I even talked to the owner of a large electric supply house in Illinois today and he had mentioned the fact that years ago they used to have recepticals that sort of locked in around the hole to hold the plug in and that there was a release to let it free.
Thanks for the info

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