I’ve always been curious about the two holes on ungrounded NEMA 1-15 plugs (Type A). There they were, one hole on each blade — what were they for?
When I had to make an electrical connection inside a junction box a few days ago, to power up a little adapter for a network camera, I thought: why not get some stubby hard drive screws (short machine screws used to afix HDs to drive bays), crimp a couple of ring terminals onto the hot and neutral wires and see if I could screw the terminals onto the adapter blades with the hard drive screws? There are no screw threads inside the blade holes, but if you turn the screws a little harder, they’re just the right width that they’ll make their own way through and the whole thing will be quite snug.
Of course, the job isn’t complete without isolating both connections separately with electrical tape, or even better, with heat-shrink sleeves, but that’s easily enough done. The last step involves placing the whole thing inside an IP 56 junction box, for extra safety.
I think it’s a fun and novel way to get power to these little adapters. What do you think?
Raoul Pop 
I’m guessing the holes are for alignment when they overmold the plastic housing. Just a guess. Otherwise, some type of alignment function.
I think what you did would work fine, covering w/ heat shrink would be a really good idea. But, if I were going to do that, I’d buy a receptacle for a cord end and plug into that. Such as one like this:
http://www.ebay.com/itm/Hubbell-Straight-Blade-Connector-15-Amp-125-Volt-Yellow-3-Wire-155071-NEMA-5-15R-/282087633638
Or, something like this in your box:
http://www.ebay.com/itm/2pcs-Panel-Mount-Receptacle-15A-120V-Nema-5-15R-Great-For-Projects-110v-115v-/301381867788
The problem w/ this last one is that you need a square hole, that kind of stinks unless you have the right punch and who has that!?
Mark
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Great suggestions! You’re right, I could have done those things, but I wanted to try something different. Not sure if you’re familiar with programming, but when I did it, it was fun to find arcane uses for various functions, just to see if a new method would allow me to do the same thing but with less code and faster. It was a contest with myself and I loved it. Same thing here. Plus, if I were to use an inline receptacle, I’d have had to use something like this (http://www.magazin-lustre.ro/adaptor_priza_220_110_usa_europa_adaptor_stecher_america_de_nord_europa-67261.p.html) plus something like this (http://www.electricdepo.ro/cuple/cupla-priza-fara-cp-legrand-50166). I’m in Romania, so that means 240V and 50Hz. And you’ve guessed it by now, the network camera does work with the electricity here, thank goodness for that.
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Raoul – On thought would be to get an old extension cord and chop off the end needed to put on the correct 120Vac/240Vac plug for the US style outlet. I’ve seen that done w/ varying success. Either way, your solution worked out and it’s smart to have it in a box. Mark
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If I’m right the holes are there because it shaved off some infinitesimally small amount of the cost to make the blades.
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If that were true, there would be more holes on the blades, perhaps 2-3 per blade. Let’s look for a more optimistic answer, shall we?
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