Eddy Current
Senior Member
Anybody know any good websites or websites with schematics that show how relays work together with lights?
Relays and Lighting for Beginners
- Thread starter Eddy Current
- Start date
- Status
mgookin
Senior Member
- Location
- Fort Myers, FL
Eddy Current
Senior Member
Im looking for a schematic that explains how lights work on a relay.
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
Simple---line power to L1, L2,....etc on the contactor/relay
load side of contactor, usually T1, T2.........etc to lights
either a manual switch or sometimes a photo cell to the coil of the contactor, also the coil needs a neutral
switch turned on - coil energized - contactor pulls in - lights come on!
Now draw this out and you have your schematic.:thumbsup:
Eddy Current
Senior Member
So the switch or photocell goes to the coil? Where do you put all the branch circuits for the lights thats the load side right?
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
Last edited:
Eddy Current
Senior Member
What if you have more than one switch like a 3way or 4 way?
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
Same way any 3-way is wired. Power to common on one switch and load (from coil) to common on the other switch.
Eddy Current
Senior Member
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
Load side of switch goes to coil on the contactor. Energized coil closes relay.
Eddy Current
Senior Member
So just like hooking up any normal 3 way or 4 way but you run the switch leg that would usually go the lights from one switch and you run it to the relay and then run all the lighting branch circuits from there.
mgookin
Senior Member
- Location
- Fort Myers, FL
On a lighting contactor or relay you have a load side and a control side. For the purpose of this discussion, let's say a relay and contactor are the same thing.
Load Side:
The lights go on the load side (because the lights are the load). Normally you're only switching the hot in which case you will have a SPST relay. Some lights require that you break all connections in which case you'll have a multi-pole relay. This load circuit is independent of the control side wiring. Often the load side and control side are different voltages. For example, it's common to have 480v lights on a contactor which has a 240v or 120v control side.
Control Side:
The switch/ photocontrol/ building management system/ etc. goes to the control side. Here you need a hot and a neutral to energize the coil which is going to switch the relay. You can get relays that use line AC voltage to energize the coil or you can get relays which use DC voltage to energize the coil. A building management system is more likely to use DCV while switches & photocontrols are more likely to switch AC line voltage.
Something to keep in mind is that relays come in normally closed (NC) and normally open (NO) styles depending if you want fail-on or fail-off. Fail-on is most common (for safety) which makes NC relays more common.
Eddy Current
Senior Member
Yeah sorry i should have titled this thread contactor instead of relays.
I know that contactors need a whole other circuit to pull the contacts in, but what im not understanding is where the hot branch circuits load and line sides going to the switch, and the same for the switch legs go related to the contactor and how it is all compressed down to one wire coming from a switch to a light.
When you say "The lights go on the load side (because the lights are the load)" are you talking about the branch circuit for each set of lights that would be on the contactor?
mgookin
Senior Member
- Location
- Fort Myers, FL
A contactor is a relay. With a smile we say relays go click and contactors go clunk. And it's common to have a control with a relay in it when the function of that control is to switch a contactor. In this case little relay switches big relay.
When I'm at my office I'll draw you up some schematics in autocad. We make outdoor light controls so I already have plenty of cad files to pick from. A picture speaks a thousand words and I think that will provide a very clear understanding. Please stay tuned...
Eddy Current
Senior Member
mgookin
Senior Member
- Location
- Fort Myers, FL
I haven't forgotten about you Eddie. If I don't get it today, then over the weekend for sure.
mgookin
Senior Member
- Location
- Fort Myers, FL
OK I'm at the office and just whipped up a little sketch. Let's do this one step at a time so as to not get confused. Let me see if I can insert a picture...
Does that make sense?
The Control Ckt (1 & 2) could be energized by a photocontrol, by a human flipping a switch, by a building management system (BMS) or in our case, by a logic circuit which runs a complex algorithm based on input parameters from GPS satellites. The load ratings on the relay (voltage and VA) determine how much load can be put on it. Remember, for our purpose, relay and contactor are the same thing.
Does that make sense?
The Control Ckt (1 & 2) could be energized by a photocontrol, by a human flipping a switch, by a building management system (BMS) or in our case, by a logic circuit which runs a complex algorithm based on input parameters from GPS satellites. The load ratings on the relay (voltage and VA) determine how much load can be put on it. Remember, for our purpose, relay and contactor are the same thing.
Last edited:
Eddy Current
Senior Member
This is all within a contactor box, no?
So the 1 and 2 are essentially like switch legs? What would be feeding the hot side of the switches on the wall, since it shows the hot leg going to the 3 terminal?
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
It might help you to just think of the line/load as completely separate from the control voltage. It is in many cases, but as I said, it can also be the same. It depends on the requirements of the coil.
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
130817-1404 EDT
Eddy Current:
You ask a lot of questions on this forum. From the nature of most of the questions it seems that you do not do any prior research or study. You need to get some of your own books that you can use for reference, use local libraries for other books, and develop techniques for Internet searching that can find background information that you want.
Internet information contains a lot of noise, and you need to learn how to filter out the noise. Your thread on Ohm's law has drifted away from the original question. You need to go back and do some research on original documentation on Ohm's work. Much Internet material on Ohm's law is very noisy. For example, Ohm had nothing to do with the equation for power. That was for Joule to study and develop. I have not gone to the U of M Engineering Library to try to look for an English translation of Ohm's original work, it is parking problem and not my major need to study. If you can get this translation, then you may be able to understand exactly what Ohm's knowledge was at that time, and what he had to think thru to develop what later became known as Ohm's law. If my reading is correct Ohm developed his concept based on conductivity, and not resistivity. I don't believe resistance was a concept at that time, but some concept of flow of electricity existed, and conductivity was a concept of how easily flow occurred. Resistance and conductivity are reciprocals of one another.
Relative to your present question in post #2 mgookin gave you the wiki reference. Go back and study that. Also look at http://www.autoshop101.com/forms/hweb2.pdf .
.
Eddy Current:
You ask a lot of questions on this forum. From the nature of most of the questions it seems that you do not do any prior research or study. You need to get some of your own books that you can use for reference, use local libraries for other books, and develop techniques for Internet searching that can find background information that you want.
Internet information contains a lot of noise, and you need to learn how to filter out the noise. Your thread on Ohm's law has drifted away from the original question. You need to go back and do some research on original documentation on Ohm's work. Much Internet material on Ohm's law is very noisy. For example, Ohm had nothing to do with the equation for power. That was for Joule to study and develop. I have not gone to the U of M Engineering Library to try to look for an English translation of Ohm's original work, it is parking problem and not my major need to study. If you can get this translation, then you may be able to understand exactly what Ohm's knowledge was at that time, and what he had to think thru to develop what later became known as Ohm's law. If my reading is correct Ohm developed his concept based on conductivity, and not resistivity. I don't believe resistance was a concept at that time, but some concept of flow of electricity existed, and conductivity was a concept of how easily flow occurred. Resistance and conductivity are reciprocals of one another.
Relative to your present question in post #2 mgookin gave you the wiki reference. Go back and study that. Also look at http://www.autoshop101.com/forms/hweb2.pdf .
.
- Status