4 way control with digital timers?

[greenspark1]

Hello,
I have a mechanical room that I would like to use digital timer switches in. There are three entrances so a four-way setup is needed. I know you can do this with standard switches, but am unsure about digital timer switches. I know they make them for 3-way operation, but haven't seen any for 4-way. I'm wondering if all 4 would be digital timers or if you need a special or manual switch in there as the 4-way switch. Any help is much appreciated!

 

[mgookin]

What are you timing/ switching? The lighting in that room? Don't you mean occupancy sensors instead of timers?

 

[greenspark1]

Yes I'm controlling the lights with a digital timer switch.
I just found out that at least one manufacturer supports it, Intermatic. They do it with 1 timer switch and 2 3-way switches. They have a diagram on their page 2 here:
link

 

[mgookin]

Seems like a risk of being surprised by darkness while working on energized equipment.

 

[kwired]

What are the goals you want to accomplish with the timer?

Repeat cycle? (On/off at certain time periods)

Delay off only for purpose of ensuring lights are not left continuously on when not occupied?

The delay off does leave the risk of automatic shut off when someone is in there should they happen to hit the timing just right.

I think occupancy sensor control may be a better solution than timer only, but still leaves some risk if someone should end up in a zone where they may not be detected, so to some degree safety may even dictate that automatic control of any kind is not worth the safety risk.

 

[greenspark1]

Yes the idea of a timer is to eliminate the possibility of the lights being left on for long periods of time while the room is unoccupied.

I definitely think occupancy sensors are a safety risk since they can be obstructed by HVAC ducts, piping, large equipment, etc. Plus if you're working in large equipment (panels) your motion could be undetected and turn the lights off. Nothing worse.

Digital timers provide both audible and visual alerts before turning off the lights. They start beeping and flashing the lights 3 minutes before shut-off, then every 30 seconds until shut off. This gives personal a great warning and chance to hit the switch if they need more time. They are also user-programmable for a longer duration if you know you'll be working for a long period of time. Whereas a mechanical timer would pose a safety risk, the digital ones really seem a good solution for mechanical rooms. Happy to hear other solutions to decrease energy use in these spaces.

 

[kwired]

Yes the idea of a timer is to eliminate the possibility of the lights being left on for long periods of time while the room is unoccupied.

I definitely think occupancy sensors are a safety risk since they can be obstructed by HVAC ducts, piping, large equipment, etc. Plus if you're working in large equipment (panels) your motion could be undetected and turn the lights off. Nothing worse.

Digital timers provide both audible and visual alerts before turning off the lights. They start beeping and flashing the lights 3 minutes before shut-off, then every 30 seconds until shut off. This gives personal a great warning and chance to hit the switch if they need more time. They are also user-programmable for a longer duration if you know you'll be working for a long period of time. Whereas a mechanical timer would pose a safety risk, the digital ones really seem a good solution for mechanical rooms. Happy to hear other solutions to decrease energy use in these spaces.

I guess you could probably find timers with the warning features you mention, won't be your typical wall switch type timer that I am aware of. Then incorporating three and four way switching scheme will make it even more rare. I'm thinking some kind of timer that has an input that would only need be a momentary contact type input, and then times out to turn off, but could still have either a toggling on/off from a single input, or a separate off input if you manually want to turn it off. Question becomes how often and for how long will the lights possibly be left on and is it worth the additional up front cost of controls compared to how much energy might be saved in say 5 to 10 years?

But then there are those that are mostly concerned about energy savings even though it may cost them more to save a little usage than what the energy itself costs, but to each his own I guess.

I guess you could go with multiple light levels as well and have a low level that is not automated just in case someone would be in there should it time out, may be a little more of a compromise that works out better from each perspective, or even put each level on a different time so you know if one level has timed out the other one will be coming, and could maybe use simpler less cost timing methods this way.

 

[greenspark1]

Here is one for $34:
http://www.intermatic.com/Products/Timers/InWallTimers/Electronic_Timers/EI400_Series.aspx
http://www.amazon.com/Intermatic-EI400C-24-Hour-Single-Pole-Auto-Off/dp/B003A1EYGC

Add two wall switches and you're good to go. Over a 20 year building life seems like it would be cost effective, especially with rising electricity costs. Ours goes up 10% in March.

 

[kwired]

Here is one for $34:
http://www.intermatic.com/Products/Timers/InWallTimers/Electronic_Timers/EI400_Series.aspx
http://www.amazon.com/Intermatic-EI400C-24-Hour-Single-Pole-Auto-Off/dp/B003A1EYGC

Add two wall switches and you're good to go. Over a 20 year building life seems like it would be cost effective, especially with rising electricity costs. Ours goes up 10% in March.

That also assumes the switch will last 20 years without needing any servicing of any kind- does say it contains a lithium battery that will last two years without AC power, what does it cost to replace should that be necessary? How many watts of lighting are you controlling, the larger number of wattage being controlled the faster the savings will add up. Only controlling 1-4 23 watt CFL's may still not be worth the investment financial wise, a larger room with several T-8 or T-5 luminaires will add up much faster.

 

[greenspark1]

Yes, I definitely agree, lots of variables to take into account. Also how often the room is used. I don't see $34 (plus labor) as cost prohibitive. But I think we've all walked into mechanical rooms that haven't been used in weeks and have all their lights blazing. In our profession I try to use products to make life better and more energy efficient.

 

[kwired]

Yes, I definitely agree, lots of variables to take into account. Also how often the room is used. I don't see $34 (plus labor) as cost prohibitive. But I think we've all walked into mechanical rooms that haven't been used in weeks and have all their lights blazing. In our profession I try to use products to make life better and more energy efficient.

At this time of year, leaving lights on reduces heating load, in summer it increases cooling load In northern regions heating season is longer than cooling season - just one more thing to consider. Electric rates vs. other energy rates is also a consideration, but at same time electric losses that contribute heat to the conditioned space are not exactly total waste during heating seasons.

 

[Stormwires]

4 way control with digital timers.

4 way control with digital timers.

How about making your four way system control a digital timer to control the switch leg to your Ltg.? Or if your Ltg. Load is is to great for your timer, you could could have your timer control a relay that closes and opens the Ltg. circuit.

 

[greenspark1]

At this time of year, leaving lights on reduces heating load, in summer it increases cooling load In northern regions heating season is longer than cooling season - just one more thing to consider. Electric rates vs. other energy rates is also a consideration, but at same time electric losses that contribute heat to the conditioned space are not exactly total waste during heating seasons.

I would like to think we can use our lights for better things than heating. Plus any heat they add to the room is above the occupied zone so doesn't help comfort levels, especially if we're talking a mechanical space.

I have heard the same argument for standby losses of an electric water heater- it's helping heat your house. Unfortunately your water heater is typically in a closet or other unoccupied area so really doesn't contribute to your comfort.

 

[kwired]

I have heard the same argument for standby losses of an electric water heater- it's helping heat your house. Unfortunately your water heater is typically in a closet or other unoccupied area so really doesn't contribute to your comfort.

Then why does an HVAC designer add a specific amount of cooling load for every water heater in the place? It is contributing heat. Heat gain or loss is just that. If it is in a unoccupied area it does not have as direct of a comfort effect but is still heat gained or lost and will have some impact on heating or cooling load. Troffers in a ceiling used for return air do not have a direct effect on comfort, but the heat they give off is pulled through the heating system and that means less energy is needed to heat the space than if this heat were not recovered. The lights in the mechanical room - true you may not get such direct comfort from heat given up by them, but without that heat the ceiling space is cooler meaning more heat near the floor will rise even faster and more heating energy will be needed for comfort. Physicists have this thing called conservation of energy. Energy is not lost, it is just displaced. If you add 100 watt hours of heat via a lighting component to a space that means your heating system has 100 watt hours less heat it needs to provide that space. If that space is in a closet, that heat eventually dissipates into other spaces, if it doesn't the closet should eventually become incredibly hot inside. Have you ever opened a water heater closet and had to stand back to let the blast of heat out before entering the closet?

 

[George Stolz]

At this time of year, leaving lights on reduces heating load, in summer it increases cooling load In northern regions heating season is longer than cooling season - just one more thing to consider.

Of course, at the same level of concern that we would place on the long term effect of the light on the wall and floor finishes.

Let's get back to the original topic. If you want to start a thread of the merits of heating via non-heating loads, you have that option.

 

[kwired]

Of course, at the same level of concern that we would place on the long term effect of the light on the wall and floor finishes.

Let's get back to the original topic. If you want to start a thread of the merits of heating via non-heating loads, you have that option.

I don't think this is all that far off topic, as the concern in the OP is energy conservation, but I will let it be from here on if that is what is desired.

 

[George Stolz]

It is.

As I read the OP, some automatic shutdown of lighting is desired at some level, and design input is requested toward that goal.

 

[kwired]

It is.

As I read the OP, some automatic shutdown of lighting is desired at some level, and design input is requested toward that goal.

Well then this must be the first time we have ever veered off topic, even just a little bit, right here:happyyes:

 

[gar]

140209-2345 EST

If I understand the original question, then logically what is desired is an on delay timer.

Let logic signal A be the output of the combination of the various 3 or 4 way switches. In other words the signal that would turn on and off the lights if there was no timer.

Let logic signal B be the output signal of the timer. The timer logic is ---

The timer is initiated by the application of an input signal = 1. B = 0 before application of the input. After a sustained input signal of 1 the output contact B = 0 until the timer times out. After time out B = 1 so long as the input signal remains = 1. As soon as the input signal goes to 0, then B goes to 0 and the timer is reset.

The desired logical signal to the lights is A and not B. The input signal to the timer is A.

After time out has occurred it is necessary to turn off A and then turn A back on.

A circuit can be designed using momentary switches that would avoid the double operation of the wall switch.

.

 

[gar]

140210-0941 EST

greenspark1:

Following is a way to do what you want and address the safety concerns:

Make the basic switching system using GE RR relay components. The control switches are low voltage (about 28 V) SPDT spring return to center. These can be mounted so that ON is always UP, and OFF is always DOWN at any switch. The ON contacts are all wired in parallel, therefore a logical inclusive OR circuit, and the same for the OFF contacts.

The RR relay is a bistable relay device with a set coil and reset coil. Momentary power applied to a coil determines the state of the relay output contacts.

Without anything else added this circuit can do what 3 or 4 way switches do with better logic as to the function of the control switches. Meaning up is always ON and down is always OFF.

The power output contacts of the RR relay directly control the light circuit.

The timer function will use the same type of on delay timer as I defined in my previous post. The input control signal comes from the output side of the RR relay. When the RR relay is set to ON, then an input signal is applied to the timer. An isolated contact is required at the timer output. This needs to be a normally open contact. This means the contact is open before application of the input control signal, remains open until the timer times out, and then closes.

The timer normally open output contact is wired in parallel with all of the OFF contacts to the RR relay. Thus, when timeout occurs the RR relay is turned off. This also removes the input signal to the timer and thus resets the timer and its output contact opens. Thus, any time a wall switch is operated in the ON direction the lights turn ON. Any time to OFF and the lights turn OFF. After the lights are turned on by a wall switch, this first setting to ON initiates the turn off timer. If no wall switch is used to turn the lights off, then the timer determines the off operation.

To address the safety concerns add one or more motion sensors. The motion sensors are all connected in series with normally closed contacts, a logical inclusive OR circuit, but using negative logic, and wired so that motion detection at any one sensor momentarily opens the control signal to the timer. This resets the timer to zero any time motion is detected. This may require a special motion sensor.

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