Patrick- a little plug blade history:
Holes in the exposed part of a plug blade are optional, according to the NEMA specification. They were once used by the large USA Receptacle mfrs as a method of retaining that plug in the slots. UL 498 requires that a receptacle retain a plug when 3 lbs is applied in a direction tending to withdraw the plug. A nib on the receptacle contacts mated with the hole in the blade. Now, that technology has changed for the large USA receptacle mfrs, and they do not need the hole in the blade. However, every other mfr in the world might still need that old technology. So the holes are still around in many applications... Dwight -- DWIGHT HUNNICUTT Sr. Compliance Engineer **************************** * <[email protected]> * * (510) 413-1349 direct * * (510) 492-0808 fax * * VINA Technologies,Inc. * * 42709 Lawrence Place * * Fremont, CA 94538 * **************************** Patrick Lawler wrote: > > I just looked at a hospital-grade cord, and it had solid, nickel-plated blades > _with_ a hole. > > Is the hole related to plug retention in the outlet? I thought I remembered > seeing small bumps on the mating blades inside the wall outlet. > > On Wed, 21 Oct 1998 08:15:52 -0800, [email protected] wrote: > >------------------------ > > From: [email protected] > > Subject: Re: Plugs for China > > Date: Tue, 20 Oct 1998 16:06:42 -0800 > > To: EMC-PSTC <[email protected]>, Millsaps Cindy-G14342 > > <[email protected]> > > > > > >> > >> > >> ------------------------ > >> From: Millsaps Cindy-G14342 <[email protected]> > >> Subject: Plugs for China > >> Date: Tue, 20 Oct 1998 16:10:33 -0400 > >> To: "'[email protected]'" <[email protected]> > >> > >> > >> > It seems that China now requires the plug blades to have no holes in > >> > them. Referring to the small round opening at the upper area of a US > >> > plug. > >> > >> > Thanks, > >> > >> > Cindy Millsaps > >> > Product Safety Engineer > >> > Motorola Energy Systems Group > >> > (770) 338-3288 > >> > FAX: (770) 338-3345 > >> > >> Sorry, Cindy, I'm of no help on your question. But, can anyone tell me > >> just what those little circular holes in the High and Neutral plug blades > >> are supposed to do? > >> > >And now, another little observation. I looked at some equipment with > >Hospital Grade cable plugs. These plugs had solid blades; no holes at all. > >And the blades were much more rigid, with slightly larger thickness and > >width than a standard plug (subjective, since I didn't have a caliper with > >me). I would think that this would create higher contact pressure with the > >female socket elements when mated. > > > >Also, the blades had what appeared to be a nickel plate finish. > > > >Regards, > > > >Ed > > > >-------------------------- > >Ed Price > >[email protected] > >Electromagnetic Compatibility Lab > >Cubic Defense Systems > >San Diego, CA. USA > >619-505-2780 > >Date: 10/21/1998 > >Time: 08:15:53 > >-------------------------- > > > > > > > >--------- > >This message is coming from the emc-pstc discussion list. > >To cancel your subscription, send mail to [email protected] > >with the single line: "unsubscribe emc-pstc" (without the > >quotes). For help, send mail to [email protected], > >[email protected], [email protected], or > >[email protected] (the list administrators). > > -- > Patrick Lawler > [email protected] > > --------- > This message is coming from the emc-pstc discussion list. > To cancel your subscription, send mail to [email protected] > with the single line: "unsubscribe emc-pstc" (without the > quotes). For help, send mail to [email protected], > [email protected], [email protected], or > [email protected] (the list administrators). --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators).
