Intermatic mechanical timer on 3way?

[SY3]

I have a barn that has some lights in it. I want the lights to turn on automatically in the morning before I get there to get the cows up and going. I have two 3 way switches that control these lights currently by two exit doors. Can I used a intermatic mechanical timer like the t100 series and keep these 3 ways?

Please help me out, I'm thinking I have to remove one switch and have a single pole set up with just your basic override switch.

 

[Dennis Alwon]

You can install a timer ahead of the switches but if the timer is on then you would not be able to turn the lights off with the switches. Feed the timer and your 3 way switches with the same circuit. Then parallel your switch leg to the load side of the timer. Technically a violation if both the switch and the timer was on.

 

[texie]

I have a barn that has some lights in it. I want the lights to turn on automatically in the morning before I get there to get the cows up and going. I have two 3 way switches that control these lights currently by two exit doors. Can I used a intermatic mechanical timer like the t100 series and keep these 3 ways?

Please help me out, I'm thinking I have to remove one switch and have a single pole set up with just your basic override switch.

You could use an Intermatic EJ 600 and still have the 3 ways operable. You need a neutral available though for this model.

 

[ActionDave]

You can install a timer ahead of the switches but if the timer is on then you would not be able to turn the lights off with the switches. Feed the timer and your 3 way switches with the same circuit. Then parallel your switch leg to the load side of the timer. Technically a violation if both the switch and the timer was on.

Some narrow room for debate if it is a violation. I have done this set up with time clocks or spring wound timers and nobody's barn has burned down to date.

 

[SY3]

You could use an Intermatic EJ 600 and still have the 3 ways operable. You need a neutral available though for this model.

I like this idea so far but wanted really to use one of those grey box timers. Don't they they are able to be used on a 3way that don't violate the nec. Just don't like how it's not very water proof as the install is in my milk parlor and we spray it down twice a day.

 

[Dennis Alwon]

I thought you wanted the gray timers however Texie's suggestion is a great one. The timer can still be used as a switch- no new wiring- just replace the 3 way at the barn with this unit

 

[pjholguin]

The intermatic with 3-way function is "ST01C". It takes the place of one the 3-way switches and looks like a Decora switch.

I like this idea so far but wanted really to use one of those grey box timers. Don't they they are able to be used on a 3way that don't violate the nec. Just don't like how it's not very water proof as the install is in my milk parlor and we spray it down twice a day.

 

[kwired]

You could use an Intermatic EJ 600 and still have the 3 ways operable. You need a neutral available though for this model.

You'd need a neutral for the T100 series timers as well

I like this idea so far but wanted really to use one of those grey box timers. Don't they they are able to be used on a 3way that don't violate the nec. Just don't like how it's not very water proof as the install is in my milk parlor and we spray it down twice a day.

As said it takes place of a switch and would accept a weatherproof decora cover.

The intermatic with 3-way function is "ST01C". It takes the place of one the 3-way switches and looks like a Decora switch.

Another option is to bypass three way switching with the timer, but you won't know if switches are in an on or off configuration while bypassed, and will resume with whatever position they are in when timer opens the circuit, which could suddenly leave you in the dark, or end up leaving the lights on all day long.

 

[arcsnsparks98]

A standard single pole timeclock, a NC relay and a NO definite purpose contactor would accomplish what the OP is wanting. The timeclock would give a 120v output in the morning, go through the NC relay and energize the NO contactor to feed power to the lights. The switch leg of the 3-way circuit would tie in with the NC relay to act as an interlock so that once someone has used the switches for local control, the timeclock will be locked out until the next morning. It doesn't keep the lights from being left on all night but it does turn them on automatically and then switch over to manual control at the flip of a switch.

Edit: The NC relay is actually a SPDT relay. I am used to motor starters with aux blocks so my terminology slipped a bit.

 

[kwired]

If using a contactor to control the lights, you open yourself to a lot of possible control schemes.

Depending on what you have and what it may take to do it, I would maybe consider changing the three way switches to Start-Stop stations and use the timer to initiate a start command at desired time but you would need to manually "stop" them at the end of day or end of milking shift or whatever. T100 series timers could be used but you would receive a "start command for at least 15 maybe even for 30 minutes - but doesn't sound like that should be a problem for the OP either.