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!!

Lockout, tagout?

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.

And here I thought they were to clean the contacts...?

Makes sense though...

Don't forget that the holes also make it easy to wrap bare wires for Mexican-style extension cords....

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!

I was told back in school that a long time ago receptacles had little spring loaded balls that would engage those holes.

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

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...

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

Luke,
Who gives a toss?.
The thing is, is that you are here giving your opinion.
This subject has come up a few times since I've been here.
Sure a lot of us older folk have seen these threads before, but to a certain degree, it means that the "younger" folk are at least still using their brains.
Don't get me wrong, I'm no better than the new kid here, I'm still learning, the day that I stop, I will be the first to tell Bill (Addiss) to cancel my membership here.
If you stop learning, you are better off dead.

Ragnar said:
[quote]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![quote]

I would have just chopped off the American plug (assume it was moulded?) and used a standard Austrian plug instead.

Less chance of indoor fireworks....

Thats really really good advice.

As for the holes, I have seen very cheaply made plugs on low-quality electronics that do not have holes in them. They still fit outlets. Just a side note.

Hey... I'm a freak
Chopping off the plug would be boring... and no, I didn't really consider using the "Mexican trick".

It's not a "Mexican Trick" at all, just a very bad trick.

I've seen #18s stuck through the holes, twisted around the prongs, and wrapped with making tape. This to run a drill press in a wood cabinet shop.

Hi Trumpy, all I was getting at was that violations such as these have probably already been documented in this forum, and ECN members that have been around this site longer than I have seen this before. Thats all.

Luke

I work in a hospital and once asked A Hubble rep.Turns out any manufacturer who makes Hospital grade plugs and recepticals install the bumps on the receptical springs and holes on the plug prongs in order to raise the tension needed to separate the two
He went on to say that hospital grade and spec grade cord caps and recepicals are made on the same assembly line.
Instead of sample testing one in every batch for acceptable tension all get tested and any that require 15in/lbs or more to remove get sent on to have the hospital grade green dot installed and price jacked up.It also helps remove the "slop factor" inharent to all mass produced products where everything averages out but are never exactly the same.
We actually have Hubbel meters(modified fish scales)with which we test every plug in the hospital once a year
I have also seen inspectors put the red tag on them for unapproved equipment.This way we cant say we didn't see it's $5000 to the person who plugs it in.