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Toggle switch keyway convention: up vs. down

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roee

Joined: 28 Feb 2011
Posts: 6
Location: San Diego, CA

Posted: Mon Feb 28, 2011 2:32 pm Post subject: Toggle switch keyway convention: up vs. down

This is a question for Bob Nuckolls as author of the AeroElectric Connection:



In the chapter on switches, it is stated that "for most applications, switches are mounted with bushing keyway oriented UP in the panel."  (Page 11-16)



However, looking at various other sources, including several switch manufacturers' datasheets as well as switch-related mil specs, it seems that the common convention is actually to mount switches with the keyway oriented down.



And another small clue in support of the keyway down convention is the most basic of all switches, the S700-1-2 described in the AeroElectric Connection itself.  The action is OFF on the keyway position and ON on the opposite position.  Common functional convention for on/off switches is ON-up / OFF-down (I don't think that's in dispute, right?).  So to conform to this convention in switching a load using a S700-1-2 switch, it would have to be oriented keyway down.



So I'd like to understand the apparent discrepancy in conventions, keyway up vs. down.  Now, I understand that either way it's just a matter of convention and is otherwise pretty much arbitrary.  But if there really is a reason that I'm not aware of to favor keyway up, then, well, I'd like to be made aware of it so I can make the most informed decision when choosing a convention for my panel.  Bob, are there such factors in favor of keyway up?



Thanks,

-Roee

tim2542(at)sbcglobal.net
Guest

Posted: Mon Feb 28, 2011 5:05 pm Post subject: Toggle switch keyway convention: up vs. down

I just ran into this myself after having my panel cut out on a CNC machine with all the antirotation tabs cut into the top of the hole. Now I guess I'll have to replace all my 1-2 switches. 

Tim

Sent from my iPhone



On Feb 28, 2011, at 2:32 PM, "roee" <roee(at)kalinskyconsulting.com> wrote:



 	  Quote: 	
		   

 

 This is a question for Bob Nuckolls as author of the AeroElectric Connection:

 

 In the chapter on switches, it is stated that "for most applications, switches are mounted with bushing keyway oriented UP in the panel."  (Page 11-16)

 

 However, looking at various other sources, including several switch manufacturers' datasheets as well as switch-related mil specs, it seems that the common convention is actually to mount switches with the keyway oriented down.

 

 And another small clue in support of the keyway down convention is the most basic of all switches, the S700-1-2 described in the AeroElectric Connection itself.  The action is OFF on the keyway position and ON on the opposite position.  Common functional convention for on/off switches is ON-up / OFF-down (I don't think that's in dispute, right?).  So to conform to this convention in switching a load using a S700-1-2 switch, it would have to be oriented keyway down.

 

 So I'd like to understand the apparent discrepancy in conventions, keyway up vs. down.  Now, I understand that either way it's just a matter of convention and is otherwise pretty much arbitrary.  But if there really is a reason that I'm not aware of to favor keyway up, then, well, I'd like to be made aware of it so I can make the most informed decision when choosing a convention for my panel.  Bob, are there such factors in favor of keyway up?

 

 Thanks,

 -Roee

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=332328#332328

mmayfield

Joined: 09 Oct 2009
Posts: 40
Location: NSW Central Coast, Australia

Posted: Mon Feb 28, 2011 7:59 pm Post subject: Re: Toggle switch keyway convention: up vs. down

Interesting question, and from my own research it seems a bit like "horses for courses" - the keyway may need to be up or down depending on your use of the switch. Eg, I have a panel plan with the 2TL1-50 switch in it for a boost pump/prime switch. The momentary action is for the prime, which will be in the "up" position, which is also the keyway position. The "off" position is opposite keyway. So the keyway must be orientated up.



On other switches I have planned like the 2TL1-10, the position of the keyway won't matter. As long as the right terminals are connected, they'll work just as intended. However on a 1TL1-2 or equivalent, the keyway will clearly have to be orientated down.



I would take "keyway conventions" with a grain of salt!

_________________
Mike

Eric M. Jones

Joined: 10 Jan 2006
Posts: 565
Location: Massachusetts

Posted: Tue Mar 01, 2011 6:22 am Post subject: Re: Toggle switch keyway convention: up vs. down

You can't get closer to the Military Industrial Complex than Eaton, and they publish this bulletin:



http://www.ee-usa.com/ProductCatalogs/Eaton/eatonXT.pdf



You will notice that no Mil-standard is called out, but they lean heavily towards "key down". Their ST switches are "key-down-off"



True, they offer plates in either orientation, but they offer switches only one way...key-down-off. This also helps shed dirt-water, when you think about it. 



The issue is settled: KEY-DOWN-OFF



Sorry, Bob.

_________________
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net

BobsV35B(at)aol.com
Guest

Posted: Tue Mar 01, 2011 7:46 am Post subject: Toggle switch keyway convention: up vs. down

Good Morning Eric,

  

 Not quite so simple!

  

 When I was making a new panel for our Piper Pacer, I wanted to make all  keyways the same so that I could do all the locking holes on the first machining  pass.

  

 I was using a whole pacel full of Klixon 7274 circuit breakers and I wanted  the amperage listing to be right side up. That required that the keyway be on  top. I was able to wire the switches so they worked in that orientation so all  seemed well. Unfortunately, I needed to install a different design circuit  breaker, but it was made by the same manufacturer. Would you believe that in  order to have the amperage number right side up the keyway had to be down? On my  most recent panel rebuild, I made all of the electrical switch and circuit  breakers so that the keyways could go either way. Doubled the work of drilling  locking pin holes, but it was consistent and easy to change the orientation of  the CBs when needed. There is NO standard! Not even within one  manufacturer's design department.

  

 Happy Skies,

  

 Old Bob

  

  In a message dated 3/1/2011 8:27:02 A.M. Central Standard Time,  emjones(at)charter.net writes:

  	  Quote: 	
		  -->    AeroElectric-List message posted by: "Eric M. Jones"    <emjones(at)charter.net>



You can't get closer to the Military    Industrial Complex than Eaton, and they publish this    bulletin:



http://www.ee-usa.com/ProductCatalogs/Eaton/eatonXT.pdf



You    will notice that no Mil-standard is called out, but they lean heavily towards    "key down". Their ST switches are "key-down-off"



True, they offer    plates in either orientation, but they offer switches only one    way...key-down-off. This also helps shed dirt-water, when you think about it.    



The issue is settled: KEY-DOWN-OFF



Sorry,    Bob.



--------

Eric M. Jones

www.PerihelionDesign.com

113    Brentwood Drive

Southbridge, MA 01550

(508)    764-2072

emjones(at)charter.net



	


  [quote][b]

JohnInReno

Joined: 08 Sep 2007
Posts: 150

Posted: Tue Mar 01, 2011 8:24 am Post subject: Toggle switch keyway convention: up vs. down

I just cut anti-rotation tab holes top and bottom. They are covered by 

the switch plates and no key orientation issues. FYI - The pull-able  

breakers seemed to require key way up.



John



On 2/28/2011 5:01 PM, tim2542(at)sbcglobal.net wrote:

 	  Quote: 	
		   



 I just ran into this myself after having my panel cut out on a CNC machine with all the antirotation tabs cut into the top of the hole. Now I guess I'll have to replace all my 1-2 switches.

 Tim

 Sent from my iPhone



 On Feb 28, 2011, at 2:32 PM, "roee"<roee(at)kalinskyconsulting.com>  wrote:

_________________
John Morgensen
RV-9A - Born on July 3, 2013
RV4 - for sale

tim2542(at)sbcglobal.net
Guest

Posted: Tue Mar 01, 2011 8:56 am Post subject: Toggle switch keyway convention: up vs. down

Thanks John, I'm not using holes, I had the key cut into the switch hole, so that won't work. But it's no big deal, I just need to use a different switch. 

Tim

Sent from my iPhone

On Mar 1, 2011, at 7:15 AM, John Morgensen <john(at)morgensen.com> wrote:

 	  Quote: 	

 I just cut anti-rotation tab holes top and bottom. They are covered by the switch plates and no key orientation issues. FYI - The pull-able  breakers seemed to require key way up.

 John

 On 2/28/2011 5:01 PM, tim2542(at)sbcglobal.net wrote:

> 

> 

> I just ran into this myself after having my panel cut out on a CNC machine with all the antirotation tabs cut into the top of the hole. Now I guess I'll have to replace all my 1-2 switches.

> Tim

> Sent from my iPhone

> 

> On Feb 28, 2011, at 2:32 PM, "roee"<roee(at)kalinskyconsulting.com>  wrote:

>

roee

Joined: 28 Feb 2011
Posts: 6
Location: San Diego, CA

Posted: Tue Mar 01, 2011 10:22 pm Post subject: Re: Toggle switch keyway convention: up vs. down

Bob's reply somehow ended up in a separate duplicate thread, so I'm re-posting it here:



 	  nuckolls.bob(at)aeroelect wrote: 	
		   	  Quote: 	
		  I would take "keyway conventions" with a grain of salt! 	


    It's been about 15 years since I did much writing

    about switches but I think the context under which

    keyways are oriented has become a bit muddled.



    Most switches are symmetrical . . . they function

    the same no matter which side the keyway faces.

    Further, the right and left sides can be interchanged

    with no observable differences in functionality.

    

    When we began to study the application of progressive

    transfer switches I published drawings with numbered

    terminals to assist the neophyte technician in getting

    wires on the right  terminals the first time. I discovered

    that the way Microswitch and Carling built their progressive

    switches was not the same. I had to publish this piece to

    make folks aware of the differences:



  http://www.aeroelectric.com/articles/Carling_Micro/Carling_Micro.pdf



    . . . right and left hand columns were functionally

    swapped between the two brands. In later years,

    I think Carling swapped their progressive transfer

    switches to conform to what the mil-spec guys

    were doing.



    Microswitch had numbers molded into their switch

    housings as did the other high-end suppliers. So

    I adopted THEIR convention for speaking to terminal

 '  numbering versus functionality.



    Once you venture out of the purely symmetrical

    world by adding spring loading to one side (or

    single pole switches with only two terminals)

    then there is risk that the desired functionality

    cannot be achieved with the keyway oriented any

    particular direction.



    This is one reason why I've always recommended

    that keyway engagement washers (shipped on all

    products offered by AEC and I think B&C) . . .

    be used on the BACK side of the panel. This way,

    the hole in the panel for the keyway engagement

    washer can be under a switch labeling placard . . .

    or be so shallow that it does not penetrate the

    panel. This allows one to have them above, below

    or even changed after initial installation

    causes one to discover the need to change it.



 [img]cid:.0[/img]



    Speaking of 'conventions' . . . you'll note

    that the panel tab and keyway tabs are on

    the same side of this locking ring. But

    I've seen them on opposite sides too.



    So the premise of this tread is correct, there

    are no industry-wide "conventions" for marking,

    functional orientation, or installation of

    switches. There ARE standards . . . many of

    them mil-specs that speak to widely adopted

    configurations. But it's a free-market decision

    by designers and manufacturers as to how

    their particular product comes into the

    marketplace. In the case of switches,

    one would do well not to stray far from

    what the majority of your competitors are

    doing . . . a Croatian market street

    vendor will find himself at a decided

    disadvantage hawking wares in Swaheli.

 

   Bob . . .

roee

Joined: 28 Feb 2011
Posts: 6
Location: San Diego, CA

Posted: Tue Mar 01, 2011 10:25 pm Post subject: Re: Toggle switch keyway convention: up vs. down

Thanks Bob et al for the responses.  I figured that would probably be the case -- the keyway up recommendation in the AEC being for some historical reasons and nothing more.  Glad to have that confirmed.  So for my panel I think I will go with keyway down for switches, as that does seem to be the more common convention in the mil specs and industry-wide.



Just a couple of general comments on other points raised in the responses:



In cases where the choice is technically arbitrary, I do think that there's value in following standard conventions in that it helps minimize possible confusion during assembly and future maintenance.  All things being equal, where an industry-wide convention exists, whether formal or informal / de facto (e.g. keyway down, I think we've now established), then that would be the default first choice.  Barring that, defining and adhering to a convention for the design (e.g. either all keyway down or all keyway up for the entire aircraft) would be the next best thing.  And finally, having a mix-and-match hodge-podge throughout would be the least desirable, though granted, occasional well-justified exceptions to a convention may still exist.



It also behooves us, when possible, to select components during the design phase that adhere to industry standards and conventions.  Doing this maximizes our ability to source spare parts in the future, including drop-in compatible products from alternate sources.  And for that reason, as has been pointed out, it also behooves manufacturers to design their products in adherence to such standards and conventions, as they make them more appealing to us in our component selection.  We've seen that not all switch (and CB) manufacturers and product lines meet that criteria, and I would factor that into my component selection process.



Thanks again,

-Roee

mathewdisoza

Joined: 25 Jun 2011
Posts: 5

Posted: Sat Jun 25, 2011 10:03 am Post subject: Re: Toggle switch keyway convention: up vs. down

Hey Bob.. . . .  . . .  .!

Cool hah

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