Unusual use of a three way.

[iwire]

Re: Unusual use of a three way.

Ahh common sense you say.

At the company I work for once week we have "Tool Box Talks" these are basically the reading of some sort safety matrial.

I had to read one with a straight face to a group of 10 or 12 guys. It was about sharp tools, it honestly had a sentence in it about not stopping a chain saw chain with your hands!

I would not be handing a chainsaw to someone that needs to be told not to hold it by the sharp end. :roll:

Common sense and self responsibility is in short supply.

 

[rattus]

Re: Unusual use of a three way.

Bob, years ago, two geniuses tried to trim a hedge with a rotary lawnmower. They merely picked it up by hooking their fingers under the deck! Sued Sears and won! Warning labels were affixed after that.

 

[leggo]

Re: Unusual use of a three way.

JES25,
I recently hooked up a furnace with a single pole, double throw switch with middle off position and it worked great.
Ed
Ortonville,MI

 

[jes25]

Re: Unusual use of a three way.

I am not understanding how a SP ST switch wired that way would work as it needs to. Regardless of the postion of the new switch the timer would continue to turn the lights on, this is not desired.....Am I not understanding?

Pierre--- I will size the box accordingly, Thanks

 

[iwire]

Re: Unusual use of a three way.

With the single pole switch on the light is on 24/7 switch off and the light is controlled by the time clock.

Rattus is right, in this application it is the simplest solution. With the override switch on the time clock ends up with a 'back feed' but it will not hurt anything.

 

[iwire]

Re: Unusual use of a three way.

Your three way will not stop the light from being on during the timer on times either.

The three way has two positions.

1)Light on 24/7

2)Light on via timer.

There is no off.

[ September 17, 2005, 10:25 AM: Message edited by: iwire ]

 

[rattus]

Re: Unusual use of a three way.

I believe the idea is to simply override the timer, not turn it off. This is no different from the override switches you find on forced air furnaces.

 

[cselectric]

Re: Unusual use of a three way.

Originally posted by iwire:
Your three way will not stop the light from being on during the timer on times either.

The three way has two positions.

1)Light on 24/7

2)Light on via timer.

There is no off.

Which is why I prefer a SP/DT center off switch for this application. Although, I suppose off could be accomplished, for a period of time, by manually tripping the trigger arm on the timer. I'm not a fan of that notion, but it would work for maintenance purposes.

 

[iwire]

Re: Unusual use of a three way.

Originally posted by cselectric:
Which is why I prefer a SP/DT center off switch for this application.

Yes of course, but many times the answer is driven from what you have in the truck.

I am very likely to have some typical 3 ways, I do not stock SPDT center off toggles.

The only time I use those are for motorized projection screens.

If I had to work on this I would probably shut off the breaker, I don't trust clocks to stay off.

 

[cselectric]

Re: Unusual use of a three way.

Originally posted by iwire:
Yes of course, but many times the answer is driven from what you have in the truck.

I am very likely to have some typical 3 ways, I do not stock SPDT center off toggles.

The only time I use those are for motorized projection screens.

If I had to work on this I would probably shut off the breaker, I don't trust clocks to stay off. [/QB]

Ah yes, the old "whats on the truck: solution. I've used that many times myself. I guess that being away from service has caused me to lose that prespective. I order what I want, the supply house delivers it. It's kind of easy to get comfortable with that situation and forget that there are times when it doesn't work that way.

I tend to agree with not trusting the timer. Then again, even a center off switch can only be trusted if it is effectively locked out (actually switches are rather trust worthy, humans not so much.) In practice, killing the breaker is always the safest option.

 

[geezer]

Re: Unusual use of a three way.

Originally posted by iwire:
Your three way will not stop the light from being on during the timer on times either.

The three way has two positions.

1)Light on 24/7

2)Light on via timer.

There is no off.

Please review the original post. There was also to be a single pole switch installed for manual control of the lighting.

So:
Position 1) Light on or off as selected manually with the single pole switch.
position 2) Light on via timer

 

[iwire]

Re: Unusual use of a three way.

Originally posted by geezer:
Please review the original post. There was also to be a single pole switch installed for manual control of the lighting.

You're right, I did overlook "a single pole upstairs" in the opening post.

So in this case a 3 - way will be needed.

 

[rattus]

Re: Unusual use of a three way.

I still don't see the need for the 3-way switch. Just wire the SPST in parallel with the timer switch.

 

[iwire]

Re: Unusual use of a three way.

Rattus with just the single pole you can not stop the lights from coming on when the timer calls them on.

If the owner wants a switch upstairs that stops the timer from operating the lights more than an SP is needed.

From my increased understanding of the opening post IMO the best plan would indeed be a DTSP center off switch installed up stairs. All that would be needed is one single gang box, the switch and the 3 wire cable from the timer to the new switch.

The switch would than have the following options.

ON

OFF

AUTO (Timer)

 

[rattus]

Re: Unusual use of a three way.

Bob,

Your suggestion is indeed the cleanest way to do it, but as I understand the description, the SPST switch merely disables the override, not the timer. If that is the case, a pair of SPSTs in series across the timer switch would suffice. To wit:

Both switches ON: Lights
Either switch OFF: Timer

 

[cselectric]

Re: Unusual use of a three way.

Actually, barring a SPDT center off, you would need a SP and a three way. Neither controls the timer (which is necessary, unless you like resetting the timer clock ) The three way has a lead from the timer on one terminal and a lead from the SP on the other. The SP switches the hot circuit (not run through the timer.) the hot circuit also goes direct (unswitched) to the timer. Therefore:

SP on, 3way down (yes thats arbitrary) = lights
SP off, 3way down = off
SP off, 3 way up = timer
SP on, 3way up = timer

I've actually seen this as a two switch override for timer controlled outdoor lighting in commercial environments. I prefer a SPDT center off because it eliminates a switch, making for a cleaner, less confusing installation.

 

[rattus]

Re: Unusual use of a three way.

cselectric, yer right!

 

[jes25]

Re: Unusual use of a three way.

Yes the three way downstairs when in manual mode will not turn the lights on unless the SP is on upstairs.

 

[LarryFine]

Re: Unusual use of a three way.

I did the exact same thing a couple of years ago when I added manual control to what was a timer-only exterior light. It only required running a single 3-conductor cable. I used a combination SP/3W switch to fit into a singtle-gang box.