Idiot needs help turning lights on and off


Thread Starter


I work for a small company with more ideas than money. We have the need to be able to turn specific lights, within a group, on and off. I don't know where to begin gathering the information my boss is breathing down my neck for. If anyone can refer me to basic info that will describe the simpliest way to achive this I will be indebted forever, well maybe not forever, but you just don't know how much it'll help me out.

Thanks for any assistance anyone can provide.


Andrew Evenson


If you say you are a VBprogrammer, there are digial I/O cards on the market that fit into you PC. All you would have to do is get the proper
drivers for the card, and write your VB code to turn the light ON and OFF.

Hope this helps

Andrew Evenson
First, find out why the idiot wants to control lighting in this manner. It might turn out there's a good reason to do so, for instance, energy savings.

Develop a worksheet which describes the type of light (fluorescent, incandescent, MH [metal halide], HPS [High Pressure Sodium], etc.), required line current for that lamp (or string of lamps), locations, desired control action, and so forth. Ask the idiot whether lamp operation will be time-based, presence-based (controlled by the presence of a person in the area), a combination of these two themes, or by something else.

Is dimming a required option? Easy for incandescent, but difficult to impossible (or, at least, a lot more expensive) for other types.

Sketch out lamp placement, and an idea of how the conduits bringing power to them make their way back to the source (usually a circuit breaker panel).

In general, gather as much information as possible before doing anything else.

Control means control elements - usually EM (electromagnetic), or, depending on load characteristics, SSR (semiconductor relays). Mercury power relays remain an option, but, for obvious reasons, are falling out of favor. These
all can switch high voltage, high current power to the lamp(s), and are turned on and off by a 'control voltage' (two very popular coil control
voltages are 120 volts AC, and 24 volts DC). The type of power control comes into play because most lamp types are highly reactive (lots of inductance and/or capacitance) and pull heavy surge currents on startup .. this works into power relay sizing and circuit protection.

I don't have any hands-on experience in this area (I work in a 24/7 operation, so local lighting control isn't a benefit), but my suggestion is
to map out areas of the lighting system where control is desired, and then call in a lighting consultant. Having done most of the legwork will keep down consulting fees. It may be you can bypass fees if, as is often the case, the consultant is on retainer to a local electrical supply house, and you end up buying necessary components from them. Also, someone (in-house
maintenance, or an electrical contractor) must already be involved in relamping these areas. Talk to them.

In general, I'd suspect it is easier (and less expensive) to put together a complex lighting system from the ground-up, rather than tacking it on later. Now, power controllers and their enclosures will need to be placed (or power
wiring brought back to one or more central control cabinets), and a control system built ... reworking conduit runs is usually time-intensive, and segments of the lighting system will be off-line while the work is being done..

If only a few points need to be controlled then an "intelligent" programmable relay like the Siemens Logo! series controller would be a perfect fit, because it can be purchased with a real-time clock feature, and was intended in part for this purpose. In a bigger system a PLC could be used, and all control brought to it (or distributed using remote I/O). It may also be possible to use X-10 modular controllers, or do a roll-your-own system using any number of different manufacturer's distributed I/O (Adam, Opto22, etc.) or even something like a Basic Stamp, or other 'embedded' computer.

A lot of these decisions depend on what the physical plant ends up becoming.

Once you have a good idea what needs to be controlled, and how much it will cost then do a payback analysis. Figure out what the energy savings will be, and compare this to the cost of renovations. If the cost can't be recouped in less than 5 or 10 years then perhaps you can get out of doing it althogether.

Unless you know exactly why you're doing this it looks like a good way to end up with even less money.

I guess you're looking for the "simplest" solution all round so this costs you the least money. The three areas of complexity that you need to think about are

1. the complexity of installation - a new installation will be simplest (cheapest) so expect a retrofit to take more time and hence cost more money
2. the complexity of the controls - if you can tell a light to switch on and off just by setting/reseting a digital output bit (controlling a switching element such as a contactor) then this aspect of the system is simple and cheap, if you have to distribute the switching around the building then provide some means of communicating with the various switching elements from a central point then things are more complex and more expensive
3. the complexity of the control system - are you going to use a PC dedicated to the task? This may fit best with your skills but may be a bit of a sledghammer/nut.

Overall it looks to me like you're probably going to spend a lot of time and money either way.

Are there simple criteria that can be defined for lights being on and off?

If they're switched depending on time then just install time switches on the light switches (you can buy these that just fit in place of single gang light switches or in more complex situations you could just mount them on the wall next to the light switch and cross wire.

If you're switching the lights off when there's no-body in the area then why not just install passive infra-red or similar motion detectors in each area controlling re-triggerable timer relays that hold the lights on for a period each time movement is detected.

If you're just trying to save money by using less energy train and incentivise the staff by telling them you'll divide the energy reduction costs between the staff in the form of a bonus.

You should also remember that many forms of lighting take a lot more power during start up than whilst running so you may actually use more power if you're constantly switching the lights on and off.

There was a similar question on the list a while ago which asked "how can I use a PC to turn a light on and off".

The simplest answer I could think of was "send an email to the person using the PC asking them to get up and flick the switch".


Geoff Moore
Straight Forward Solutions Ltd
Maynooth Road, Prosperous,
Naas, Co.Kildare, Ireland
Phone : +353 (0)45 892739
Fax : +353 (0)45 893880
Mobile : +353 (0)86 8179683
email : [email protected]

Alan Rimmington

If all you need to do is turn some lights on and off from a PC you could look at Home Automation, they have a master unit that links to the PC and a mains socket, and slave units that go between the item to control and its mains supply. All signals between master and slaves are transmitted over the mains cabling, thus saving on wiring. Just make sure that the master, and all the
slaves are on the same electrical phase. Would need more details of the actual use and location to advise further, but your first stop should be...


"Idiot" is such a negative word, I really don't like to see it in the subject line of a message, even if it meant to be jokingly self-referential.

Or maybe you're referring to your boss?

Besides, an idiot wouldn't be able to find his way to the A-List and post a question, much less understand the answer.

However, you do lack a little schooling in how to ask for help. The value and accuracy of a solution is proportional to the precision of the problem statement.

What types of lights are you talking about? Are you doing Stage Lighting in a theater? Building Lighting? An LED annunciator panel? Home automation?

Are you controlling these programmatically? Is it being driven by an
operator, or by timers, or by some other automatic inputs?

Is this for "On-at-Dusk, Off-at-Dawn" application? Or are you doing high-speed
strobing techniques to do Bullet-Time video/film recording for Matrix III?

You're a VB programmer, so I assume you have a PC and are running Windows? Anything else you can tell about the hardware you are working with?

These are the types of questions that need to be answered before you can determine the feasibility and cost for what you're trying to do.

But just for starters, go to google: "": and search for: Computerized Lighting Control

I did, and got 35,000 hits. Put quotation marks around it and you still get 150 hits.



Derrick Dawson

I am not a programmer but a friend and I were playing around with some lights and a horn. We made a VB form that gave us a visual of inputs and outputs we used an AB micrologix connected to the serial port. We were able to toggle lights on and off. A nice simple $30.00 book told me how to do this, Home Automation Basics: Practical Applications Using Visual Basic 6 get that book as a programmer you should have no problem. You can get this book at Amazon. I will call in my chip in the future ;0)

I had a responder to my posting that was offended by my posting's subject line. My descriptive phrase was meant to describe myself in a humorous manner. I regret if anyone interpreted my attempt at humor as rudeness.

I did recieve several helpful responses to my posting for which I am very appreciative.

Thanks for the help, sorry if I failed to comply with accepted protocol on postings.


M. Harisman - Integra Teknik

Instead of using PLC, external controller, or internal PCI/ISA I/O Card, for a very simple system - you could have eight (8) Digital
Inputs/Outputs from your LPT port that be coupled to a proper realy(s). For this you just need to learn how to send byte and also receive byte
from LPT using a program language you are familiar with.

M. Harisman