Nobody really ever thinks about this, but why do electrical plugs have holes in them? Back in , a scientist and inventor by the name of Harvey Hubbell patented the United States electrical plug socket. He was the original inventor of the two holes in US plugs people are so familiar with today. Those original two holes were designed to prevent the plug from falling out of the socket, which of course made sense — then.
Today, however, the sockets are a completely different design, relying on friction to prevent the plug from falling out — which renders those holes useless. One idea out there — which is likely a myth — is that way back then s those two holes could allow someone to lock a plug with a plug lock, preventing someone from using a particular device or appliance.
Mobile Newsletter chat dots. Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. Household Appliances. Updated: Apr 1, Why do the prongs on the electrical plug have holes in them? 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 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. For example: To keep kids from plugging in electrical items or to lock out electrical appliances for repair.
This was mandated back in for safety, Lock Out-Tag Out. Many years ago you could purchase a small lock at your local grocery store that supported those cord ends. Now not so available. You can do that same trick with small zipties. Then they figger out it wasn't a joke. A small padlock could be used to prevent someone from using an appliance. For example your teenager is grounded, so you lock the cord on the tv, or game console. Also like mentioned above you could tag out an appliance for service.
Wow, no. The holes are there because UL requires certain tests to be done in order for power cords to be "certified". Those holes are only there because one of the UL tests involves sliding a rod through those holes to perform the pull test. If you have a plug with no holes, it is a non certified knock off. Chinese fake. I am a power cord manufacturer in North Carolina.
They could grip the prongs with "Vise-Grip" type of clamps for their pull test instead of requiring the extra drilling step for all of the zillions of production plug prongs. Wrong answer. Now that i think about it, all the hole-less plugs I have are things like USB wall chargers, e.
There are definitely leaf springs that mesh with the plug holes inside an outlet, I took one apart awhile ago out of curiosity. I wonder if they came first or they took advantage of the existing holes for the UL test. Leaf springs are only to make good firm electrical contact. Zero strength pushing tangentially against a hole.
Not so, because there are spherical bumps like ball detents which engage in the hole, as the original post mentions. Do you know if you can permanently plug prongs into a outlet? I assume you couldn't because tripping over the cord could cause damage to an outlet. I've done a light search and find anything in codes or UL. Can anyone point me to a code or legal restriction against "locking" into a socket?
Not sure Aaron as to why you would want to do that epoxy will do the trick of you really want to go ahead , as you're then committing that outlet to the plug in question. If anything were to happen where the plug or cord needs to be replaced such as a frayed cord , you then have to replace the whole outlet in addition to the plug. Legally, it depends on where you are as to what code violation if any , such a task would constitute.
Best to ask a locally licensed electrician, although odds are that they will try to talk you out of it for the sake of practicality regarding the outlet. While it might be worth questioning if permanently affixing a plug into an existing outlet is a good idea, aren't there already situations where an item is permanently connected to the building's wiring? Is this possible in a home system? Wow very nice post its all information is really great for electrical adapters. A website can serve its purpose more effectively if the site is user friendly.
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