[GreenKeys] Switch polarity

[Scott Johnson]

Convention in the commonwealth seems to be up for off, everywhere else seems to be opposite.  In aerospace, up is on, for a vertical panel, forward is on, for an overhead panel, and outward is “on” for a side panel.  BTW, in north America, the grounding terminal on a NEMA 15  is SUPPOSED to be up, even the writing on the outlet bears this out, but I think design folks liked the “face” look, so down is common.  In some locales, and in Canada I believe, ground up is enforced.  The rationale is it is first to make, last to break, and you should be able to visually align the plug with the receptacle using the ground pin.

 

Scott V. Johnson W7SVJ

5111 E. Sharon Dr.

Scottsdale, AZ 85254-3636

H (602) 953-5779

C (480) 550-2358

 <mailto:scottjohnson1 at cox.net> scottjohnson1 at cox.net

 <mailto:scott.johnson at ieee.org> scott.johnson at ieee.org

 

From: GreenKeys [mailto:greenkeys-bounces at mailman.qth.net] On Behalf Of drlegendre .
Sent: Saturday, May 27, 2017 8:34 PM
To: WA5CAB at cs.com
Cc: Green Keys <greenkeys at mailman.qth.net>
Subject: Re: [GreenKeys] Switch polarity

 

Pretty sure that "up for off" convention is a result of the Commonwealth.. IIRC, many of the 3-pin Euro mains plugs expect the 3rd terminal to be up vs. down as in American systems. 

 

The one that always gets me, is the reverse standard for valving on locomotives. In most any case, a ball valve is open when the lever is parallel to the line (makes sense). But I was told this is the direct opposite of the railways, where the valve is open when the lever is perpendicular to the line. 

 

Confirm, deny, excoriate? 

 

On Sat, May 27, 2017 at 10:08 PM, WA5CAB--- via GreenKeys <greenkeys at mailman.qth.net <mailto:greenkeys at mailman.qth.net> > wrote:

Because they are in the northern hemisphere?  :-)

In a message dated 05/27/2017 21:30:46 PM Central Daylight Time,  <mailto:dave at horsfall.org> dave at horsfall.org writes: 



One thing that's been bothering me when watching old American films; why 
are their switches always upside-down i.e. flip it up for "on"?

-- 
Dave Horsfall DTM (VK2KFU)  "Those who don't understand security will suffer."



Robert & Susan Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480
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