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two SPST to light one light bulb?

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or ciruit
5K views 44 replies 15 participants last post by  Shockdoc 
#1 ·
Hi,
I am sure this was asked before but couldn't find anything on search. So there we go.

Can you make a OR light bulb circuit with two SPST? (I am sure it can be done, the question is more, would it pass the code?)

What I mean by this is that I want to have two SPST and connect hot together and neutral together so that, only one of them needs to be on to light the light bulb. Using two SPDT would make AND circuit, but what I need is OR circuit.

The variation of this would be, 1 SPST + relay from the garage door opener light bulb. Basically I want to be able to turn the light on either -manually with the switch, or when the garage door opener relay is closed.

Thanks for your input
 
#11 ·
Defective premise. You CANNOT make a true Or circuit with two SPST switches. You can only make an And circuit, or you man make a "half duplex" Or circuit, in that if the light is Off, then either switch can turn it On and Off from ONLY that switch, and only as long as the other switch is left alone. But if you turn it on with A, you CANNOT turn if Off with B, and vice versa. A true Or circuit would require that. This is what 3way switches provide.
 
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#19 · (Edited)
pilobond said:
Why not? I gave you a very practical example above as well. Just because your imagination is lacking doesn't mean other people will never need it...
Well I guess after doing this electrical thing for 30 years I've seen a lot. And a light wired the way you asked would not be wanted. I see both switches closed and someone standing next to one flipping it on and off with no results. Then leaving it like they found it and going to the other one with the same result. But hey, that's just my imagination running wild.

I just realized you're an engineer, now I understand.
 
#21 ·
Well I guess after doing this electrical thing for 30 years I've seen a lot. And a light wired the way you asked would not be wanted. I see both switches closed and someone standing next to one flipping it on and off with no results. Then leaving it like they found it and going to the other one with the same result. But hey, that's just my imagination running wild.

I just realized you're an engineer, now I understand.
I'd like to say politely, but, whether wanted or not by the mass is not your problem really. Also I know how to wire SPDT safely and as per code. Thank you very much. Doesn't take lots of skill really. And stop talking about people flipping switches and expecting anything. I gave a good example. Did you read it?
 
#25 · (Edited)
Don't mind backstay, he's the resident grump.

Your thread will be locked soon. Do you have any last words?
Well.. I would apprecite any real answers, other than complaining that no one ever wanted it and no one has ever done it. Any competent electrician to take the challenge? (Or do you tell your client "no one has ever done it or wanted it so your needs are ignored.")
 
#23 ·
And really going back to the original question... (and forgetting if anyone else "needs" this kind of circuit) would really be the only way to solve the "example" I have given (let's make it simple, one switch, one garage opener, one light bulb)? Any original thoughts to solve this cost-effectively?
 
#27 ·
Ok. this is waste of time. How more specific does it have to be? (Did you really read my original post?) One light switch, one garage door opener, and both will control one light bulb with OR logic. I don't think it will get any more specific than that.
 
#42 ·
pilobond said:
Well.. I would apprecite any real answers, other than complaining that no one ever wanted it and no one has ever done it. Any competent electrician to take the challenge? (Or do you tell your client "no one has ever done it or wanted it so your needs are ignored.")
My "clients" aren't so cheap that they want to only light their garage with the opener light. Also most wall controls already do this, which has been pointed out many times. Plus you have a bad attitude.

Grumpy
 
#43 ·
pilobond said:
I don't see why you cannot make OR circuit with two parralel SPST switches. In fact, I think it's quite obvious. You turn either or both of them on, the light turns on. There we go.

That is an OR circuit.
This is a simple boolian math logic equation and ignoring half of an equation does not make your solution valid

That's not a full Or circuit, because the light can only be turned off as an And circuit. A light has two states, On and Off, you are only describing the first half of the problem solution, turning the light On.
 
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