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From: hermann@calgary.UUCP (Michael Hermann)
Newsgroups: sci.electronics
Subject: Re: WHat are those holes for?
Summary: Holes in electrical plugs
Message-ID: <1752@vaxb.calgary.UUCP>
Date: 18 Jul 88 19:07:44 GMT
References: <10790@oberon.USC.EDU>
Organization: U. of Calgary, Calgary, Ab.
Lines: 19

In article <10790@oberon.USC.EDU>, robiner@ganelon.usc.edu (Steve) writes:
> I'm sure this is below the level of most of the people in this group,
> but...
> 
> Why do standard electrical plugs have holes in the metal prongs?
> 
> =Steve=


Lots of industrial type units for three-phase power etc. have a locking 
mechanism that either involves rotating the plug, or using a latch that locks
some internal pins into the plug thru the holes. Safety feature, prevents 
accidental disconnection (ie. seen these outlets in hospitals, where heart
monitors etc. are plugged in).

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