# 277V Lighting Issue



## frenchelectrican (Mar 15, 2007)

Hello and welcome to Electrician talk .,,

wow nice story .,, 

OK there is couple items I will ask ya .,, 

is all your circuit in EMT or MC cable ? because I want to clear that part first.

second thing with neutral at any voltage with properly connected it should be 0 volts if you mesure from neutral to a knowen good ground source ., any more than that then you got issue somewhere along the circuit.

senice you mention HVAC crew been working in that area you will have to look at the conduit and MC cable little more closer to make sure there is no damage along the way and with EMT conduits it can pop apart if you are not aware of that. ( that you have to be carefull with it ) 

You should start where the luminaires are working first then work it way down maybe a open hot or open neutral conductor connection which it is kinda common when someone remove the luminaires so start there.

as I will mention again just be extra carefull with 277 volt circuits they can really bite your arse if not heeded ., and expect that may end up being on MWBC ( multiwire branch circuit ) so just prepared for it. 

and also before I forget anything else make sure you are aware if you have any motion sensor or dimmer controls in the circuit that is the other part ya have to keep in your mind on that. ( sometime it can be show up in the lighting conduit part so just be aware of it if that ever show up ) 

You did not mention if this was flourscent or LED luminaires .


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## davemica (Sep 23, 2011)

Im guessing there are probably more unstripped wire nuts. A wiggy to place a load on what you are testing is needed otherwise you may be chasing phantom voltage.


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## LasVegasJDub86 (Sep 13, 2017)

Thank you for the input guys. The raceways used is basically EMT trunked around with FMC branched off to J-Boxes. No motion sensors here, as I stated I open up the light where the ballast is (oh these are flouresant lights) and I have power AT THE LIGHT!! and I highly doubt 60 bulbs are bad lol


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## eddy current (Feb 28, 2009)

Put your volt tick away and use a real meter. Then test if you actually have power (277 volts) at the light


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## LasVegasJDub86 (Sep 13, 2017)

????


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## LasVegasJDub86 (Sep 13, 2017)

Roger That!


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## frenchelectrican (Mar 15, 2007)

eddy current said:


> Put your volt tick away and use a real meter. Then test if you actually have power (277 volts) at the light


That is the only way you can verify the correct voltage at the luminaire once you verify it then go from there.

if you have multi wire branch circuit that will smoke any other ballast due those 277 volts ballast will not take 480 volts so once you end up 480 volts it will smoke those ballast fast. 

so just be aware of that.


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## Helmut (May 7, 2014)

Are the disconnects for the ballasts, in the lights plugged in?


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## cdslotz (Jun 10, 2008)

Who was part of this "process" that took them down?
Someone from your company?


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## EC2253 (Mar 7, 2008)

LasVegasJDub86 said:


> Thank you for the input guys. The raceways used is basically EMT trunked around with FMC branched off to J-Boxes. No motion sensors here, as I stated I open up the light where the ballast is (oh these are flouresant lights) and I have power AT THE LIGHT!! and I highly doubt 60 bulbs are bad lol


Some where a neutral was opened and the ballasts got 480v, so now you have more work.


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## mpoulton (Jul 17, 2009)

LasVegasJDub86 said:


> Thank you for the input guys. The raceways used is basically EMT trunked around with FMC branched off to J-Boxes. No motion sensors here, as I stated I open up the light where the ballast is (oh these are flouresant lights) and I have power AT THE LIGHT!! and I highly doubt 60 bulbs are bad lol


When you say you "have power", does that just mean you have 277V to ground on the hot conductor, or did you actually confirm 277V directly between hot and neutral at the ballast using a low impedance meter? With the ballast connected and power on, what do you measure between neutral and ground?

Are these multi-wire branch circuits? If so, the open neutral problem may well have fried all those ballasts.


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## LasVegasJDub86 (Sep 13, 2017)

So someone from my company is responsible for disconnecting these lights and taking down certain lights.I am not sure who because it looks to me as if they got transferred to another job and you know how it is basically it's not about who did it it's just about getting it fixed although it would help to know the process they took to disconnect these things because as you mentioned getting 480 at the light and frying these ballasts is not good . As I mentioned I started troubleshooting this at the end of my shift only using my tick tracer thinking this would be a simple fix because the previous three rooms I did I had no issues. Today when I go in I will use my multi-meter and start getting some answers. Can you normally see visually if the Ballast has been fried? Because the couple that I opened up to make sure there was power and yes the disconnects are on everything is connected in the Ballast there is no visual signs of damage . Thanks for the input guys. I will make sure to post what I found out today. I go in at 2:30pmPST

-M


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## GeneC (Aug 28, 2017)

You are way to young to pull your hair out. If all was good at start and now its foobar then somebody F'd up. Try to find out as much info as you can before digging in. You mention fmc and ac duct work. Any mc feeds? sounds like you got a crush somewhere. had this happen to me on a 277/480 supply once. Took a while to find. If all was good before I would look for a mess up. Check voltages first with a meter not a ticker. It is a good possibility that 480 was sent to those ballasts, not likely though cause too many lights. Somebody did something and did not say what happened. I have these issues all the time everybody just covers their buts and moves on. Like I said before Check for somebody screwing something up. Especially when other contractors are involved. There is no respect of trades anymore and it's every man for himself. Good luck man


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## LasVegasJDub86 (Sep 13, 2017)

GENEC- WOW! You could not have said it any better ! I go into work yesterday to start the "real" troubleshooting. I start with the switch to test V with switch on and off , line side 277V load side, with the switch OFF, 96v!! I go to the first light with switch off and I'm reading 96V on SL(feed to the light) wth??!! I then follow the half inch conduit which leads right outside the classroom door, with a Jbox right on the outside above the door in a corridor , I open the box and see a few things. 
ONE- my neutral has been cut
TWO- there are two wires coming from a jbox which was OBVIOUSLY just installed right next to mine with a nipple attached to my jbox . Turns out the company who is doing the fire alarm needed to steal 277V from us to power their transformer whatever it was they stole our neutral and pigtail off our switch leg and on the load side of their transformer they were sending 24 V down to our switch !!!!!! WTF???? I took pictures let the owner of my company know, disconnected their garbage ,pulled the new neutral in and voilà !!!! Lucky we had no issues with the ballasts. You are absolutely correct about these careless rat company's who will do anything to get their stuff done!!!


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## LasVegasJDub86 (Sep 13, 2017)

Im sorry I meant their "RELAY"


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## macmikeman (Jan 23, 2007)

The problem is because they originally used wire nuts, when as all the smartest people on this forum like to remind us all, a 66 punch down block would have looked better.


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## frenchelectrican (Mar 15, 2007)

LasVegasJDub86 said:


> GENEC- WOW! You could not have said it any better ! I go into work yesterday to start the "real" troubleshooting. I start with the switch to test V with switch on and off , line side 277V load side, with the switch OFF, 96v!! I go to the first light with switch off and I'm reading 96V on SL(feed to the light) wth??!! I then follow the half inch conduit which leads right outside the classroom door, with a Jbox right on the outside above the door in a corridor , I open the box and see a few things.
> ONE- my neutral has been cut
> TWO- there are two wires coming from a jbox which was OBVIOUSLY just installed right next to mine with a nipple attached to my jbox . Turns out the company who is doing the fire alarm needed to steal 277V from us to power their transformer whatever it was they stole our neutral and pigtail off our switch leg and on the load side of their transformer they were sending 24 V down to our switch !!!!!! WTF???? I took pictures let the owner of my company know, disconnected their garbage ,pulled the new neutral in and voilà !!!! Lucky we had no issues with the ballasts. You are absolutely correct about these careless rat company's who will do anything to get their stuff done!!!



I am glad you did found the bad fish there .,, that kinda expected to show up like that especially with some remodeling going on and some case they ( other trades ) dont always tell ya what their gameplan is.

I think the reason to add a relay on fire alarm circuit due it will override the wall switch when the alarm kick on it will force the light(s) to come on if the wall switch is off postion.

that is one possibility per your state or local fire codes may add to that.


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## LasVegasJDub86 (Sep 13, 2017)

French: yah that is not the case here, in other classrooms they stole our power but not at the switch, it says nothing on our plans about this . Not sure exactly what they are doing with that relay. All I know is it would have been nice if their foreman cAme and communicated this with us, instead of blatantly destroying our electrical for THIER benefit.


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## LasVegasJDub86 (Sep 13, 2017)

Now that I am looking more closely, so if the FA has to do something with those FA and our lights, which I have never seen before .. what could they be doing with this relay? I have yet to talk to them but on the relay it is talking about 277 flouresant lighting Ballast I believe. ?? Any options ??


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## LasVegasJDub86 (Sep 13, 2017)

Opinions***


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## frenchelectrican (Mar 15, 2007)

LasVegasJDub86 said:


> French: yah that is not the case here, in other classrooms they stole our power but not at the switch, it says nothing on our plans about this . Not sure exactly what they are doing with that relay. All I know is it would have been nice if their foreman cAme and communicated this with us, instead of blatantly destroying our electrical for THIER benefit.


I think that is the major key is commutation between other trades .,

if they keep the commutation open then it will not be much a mess.

I went thru like that before few time when they dont commuate to me and I just let the Project super know about it and get my side done. 

I have few good other trades working with me with good commutation so we know what they are up to and do as we work around it without major issue.


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## frenchelectrican (Mar 15, 2007)

LasVegasJDub86 said:


> Now that I am looking more closely, so if the FA has to do something with those FA and our lights, which I have never seen before .. what could they be doing with this relay? I have yet to talk to them but on the relay it is talking about 277 flouresant lighting Ballast I believe. ?? Any options ??


that what I belive some state fire marshals or inspectors adding to that related to the fire codes.

I do not know which fire codes you are using in your area I know the NFPA 70 is common one but the state / Local codes may add it to your area.

We have couple school in Philippines that hook up the same way when the FA kick on the classroom lights go on ( the FA will override it reguardless if switch is on or off ) 

but the main thing is talk to your boss for more detail on this one if they willing to expain some details then they will be happy to fill ya in on that.


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## LasVegasJDub86 (Sep 13, 2017)

Yes this is what it looks like. Although I have worked in many schools and I've yet to see them do this . But yes it looks as if they are assuring that after loss of power emergency lights will stay on no matter what. Only problem is they HAD ABSOLUTELY NO IDEA HOW TO WIRE UP THE RELAY! ???


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## Signal1 (Feb 10, 2016)

LasVegasJDub86 said:


> Yes this is what it looks like. Although I have worked in many schools and I've yet to see them do this . But yes it looks as if they are assuring that after loss of power emergency lights will stay on no matter what. Only problem is they *HAD ABSOLUTELY NO IDEA HOW TO WIRE UP THE RELAY! ???*



Obviously not.

I see the red MC, but are you sure it is for fire alarm? Those Mytech things are usually wired to an occupancy sensor.

Maybe they are using it to interface with FA somehow as @frenchelectrician said, but they should have left the line side for you to wire, and not touched your stuff.


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## frenchelectrican (Mar 15, 2007)

LasVegasJDub86 said:


> Yes this is what it looks like. Although I have worked in many schools and I've yet to see them do this . But yes it looks as if they are assuring that after loss of power emergency lights will stay on no matter what. Only problem is they HAD ABSOLUTELY NO IDEA HOW TO WIRE UP THE RELAY! ???


That is a serious issue and I do not know how widespread they done to the lighting system in the school.

typically I useally see red MC that give me a clue that is typically reserved for Fire Alarm system unless marked otherwise.,,

that going be a pretty good backcharge on that mess.

if that the case the FA contractors should talk to your crew in first place and disccuss the proper way for termation on line side.

did someone used that relay for master lighting control panel ? that is the other question that do come up. I heard some larger schools use that for master lighting control to shut off a lot of unused room luminaires .,, so that is the other thing you need to check it out. 

But more likely a fire alarm system.,,


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## GeneC (Aug 28, 2017)

LasVegasJDub86 said:


> GENEC- WOW! You could not have said it any better ! I go into work yesterday to start the "real" troubleshooting. I start with the switch to test V with switch on and off , line side 277V load side, with the switch OFF, 96v!! I go to the first light with switch off and I'm reading 96V on SL(feed to the light) wth??!! I then follow the half inch conduit which leads right outside the classroom door, with a Jbox right on the outside above the door in a corridor , I open the box and see a few things.
> ONE- my neutral has been cut
> TWO- there are two wires coming from a jbox which was OBVIOUSLY just installed right next to mine with a nipple attached to my jbox . Turns out the company who is doing the fire alarm needed to steal 277V from us to power their transformer whatever it was they stole our neutral and pigtail off our switch leg and on the load side of their transformer they were sending 24 V down to our switch !!!!!! WTF???? I took pictures let the owner of my company know, disconnected their garbage ,pulled the new neutral in and voilà !!!! Lucky we had no issues with the ballasts. You are absolutely correct about these careless rat company's who will do anything to get their stuff done!!!


Hey man, I am glad to hear that. I am familiar with those systems you describe, and they totally wired it wrong, in addition the FA co. should have consulted with electricians. I didn't think 480 through ballasts was possible cause even if Jbox had Multi ckts. they would have to f with the wiring. as it is they did enough. I deal with it every day and after a while you just know what to go at. Where I'm at everything is independent of FA system and use battery back ups in fixtures with all the other exit and emergency lights. Iv'e been at this a long time so just remember to keep it simple stay by your self and no pressure. Be your own man sounds to me you got a good head and you'll go far. Keep the BS off your back you will do fine.


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## dmxtothemax (Jun 15, 2010)

I will bet that the other end of your not conectted neutral wire is floating also !
This would account for the detected voltage on it.
Most likely a phantom voltage.
You see to be on the right path,
please continue


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## LasVegasJDub86 (Sep 13, 2017)

GENEC- Thank you for your post. You seem to be a very logical smart electrician. So tonight my foreman talked with the FA company and they denied every touching any of that. They said it was "exsisting" . Only problem is ,the lights in that classroom working jus fine pre-construction. And they are the only ones who are doing FA. It is an entire HVAC controls/Electrical( which my company is doing) and an entire FA upgrade . Which is another contractor. Ok so tonight I had a few extra minutes to look into this because the other 5 rooms look to have that same mini battery backup relay with no issues. So whoever wired up that one specific one is really love to give him a piece of my mind . GeneC: maybe you can explain to me exactly what they are doing here. Here is a classroom in which they have this relay wired . I guess I just want to understand the reasoning for this. Like I said these lights are not on a lighting contactor or any motion sensor. (See attached pictures) thanks everyone for your input . Like I said I am 30 years old. I went through the IBEW apprenticeship and have been doing electrical since (about 9 years) I have so much to learn and really love my job. Hardest part is dealing with others who are assholes or who treat me like a kid. That is the hardest part for me. I have to earn respect by showing what I can do.as you can see their FA goes into our lighting feed jbox that goes directly to the switch.


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## telsa (May 22, 2015)

Signal1 said:


> Obviously not.
> 
> I see the red MC, but are you sure it is for fire alarm? Those Mytech things are usually wired to an occupancy sensor.
> 
> Maybe they are using it to interface with FA somehow as @*french*electrician said, but they should have left the line side for you to wire, *and not touched your stuff*.


They broke the fundamental job site rule: don't mess with the other guy's stuff.


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## B-Nabs (Jun 4, 2014)

Googling that part number shows that it is a power pack made by Hubbell automation. These devices are used in conjunction with low voltage control devices such as occupancy or daylight sensors. I doubt it actually has anything to do with the fire alarm. The fire alarm cable was likely used because it is an armoured 18 gauge multi conductor cable. We do this frequently and there is no issue with it. It would have been better for them to use regular unpainted cable rather than the red, but what are you gonna do.

So the presence of these devices tells me that there are, in fact, sensors in use to control these lights, despite what you may believe or have been told. 

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## LasVegasJDub86 (Sep 13, 2017)

BNABS- I am so glad that I signed up to this forum. There are so many smart guys on here and I have really been able to obtain some reasonable logical answers thus far. Due to the construction in the classrooms with no ceiling tiles in I scanned the room multiple times and saw no motion sensors until the last five minutes of my shift today. In the very center of the room coil dad up above the ceiling obviously because there is no ceiling tiles yet, The sensor was tucked away in the ceiling barely visible. Why they use red fire alarm cable I don't know but it seems that we have come to a conclusion . No wonder why the fire alarm guys seemed so surprise LOL I just still am wondering why in that one classroom our neutral was cut and the wiring for that relay was completely screwed up because before construction that room was completely lit up no issues !


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## LasVegasJDub86 (Sep 13, 2017)

BNABS - So if you can, can you please explain what the 277V is for , the 24V and the control wire and the process of this relay. (Basically explain it to me as if I'm a re-tard lol . I always get confused when I look at the relay schematic in what is doing what . And I HATE not understanding stuff. But I LOVE learning . Thanks again guys


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## frenchelectrican (Mar 15, 2007)

LasVegasJDub86 said:


> BNABS- I am so glad that I signed up to this forum. There are so many smart guys on here and I have really been able to obtain some reasonable logical answers thus far. Due to the construction in the classrooms with no ceiling tiles in I scanned the room multiple times and saw no motion sensors until the last five minutes of my shift today. In the very center of the room coil dad up above the ceiling obviously because there is no ceiling tiles yet, The sensor was tucked away in the ceiling barely visible. Why they use red fire alarm cable I don't know but it seems that we have come to a conclusion . No wonder why the fire alarm guys seemed so surprise LOL I just still am wondering why in that one classroom our neutral was cut and the wiring for that relay was completely screwed up because before construction that room was completely lit up no issues !


That is pretty unsueal to see the motion sensor in that location but however I think the motion sensor is used to control room lighting level. sometime it may have a photocell inside of it so whatever over X number of footcandles it will turn off the luminaires to save engery on it.

but however somecase for sectuerty purpose too when someone come in the room and not turn the light switch on those sensor will kick the light on. 

so that is one of couple possibility they use the motion sensor in there.

I have ran into one school sometime back in large classroom they have motion sensor hooked up for that purpose so to save energy but one other classroom it is the other way around.


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## B-Nabs (Jun 4, 2014)

277v is the voltage the light runs on. 24v is the voltage the sensor runs on. The power packs plays two roles:

It transforms the 277v to 24v for the sensor(s) to use.
It acts as a relay, controlled by the sensor(s).

So the small gauge red and black wires supply 24v power to the sensor(s), and the blue small gauge wire carries the control signal from the sensor(s) back to the coil of the relay inside the power pack.

On the other side of the power pack you have 4 larger gauge wires: one white, one black, and two red. The white and black supply 277v to the transformer portion of the power pack. The red wires are connected to the normally open contact controlled by the low voltage coil. A common way to wire this up is to connect the black and one of the reds to the incoming 277v constant hot, the white to the neutral, and the remaining red to the switch leg going to the light. If, however, you want to use one circuit for control and a different one for the lights, that is also possible.

Have a close look at the wiring diagram and hopefully you can make sense of it. It seems these devices are more and more common these days, what with increasing energy saving legislation coming into effect in various jurisdictions. 

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## LasVegasJDub86 (Sep 13, 2017)

Thank you very much for taking the time to explain that . So let me see if I understand this. Let's say the switch in the room is on but the room is not occupied so the coil is open? Someone walks by the sensor and the control wire from the sensor tells the relay to close (completing the circuit ) and lights go on? Am I anywhere near close to understanding ? I get what the input out voltages are for I assume connecting the black,red and incoming 277v does (2) things ; powers up the line side of the transformer and also breaks the connection of the switch leg, then the actual switch leg coming off of the switch is tied to the other red...? Did I butcher this or what lol


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## B-Nabs (Jun 4, 2014)

I can't quite tell from your pictures, but I think in your application they've got the wall switch wired in series with the NO contact on the power pack, such that both the switch must be on AND occupancy must be detected in order for the lights to come on.

In this way they are achieving a sort of crude manual-on auto-off scheme. That is, you walk in, turn on the switch, sensor sees you, lights come on. As you leave, you may turn off the switch, but if you forget, the sensor will time out and turn them off. 

Additionally, the switch allows the lights to be turned off manually, for instance for a presentation or something. I say it's crude, because there are schemes involving more sophisticated power packs, known as room controllers, or even more complex systems involving whole facility lighting panels, in which the wall switch is also low voltage.

In these systems, when you leave the room and the sensor times out, the system returns to its default setting. That is to say, with it wired the way you have it, if you leave the switch on, then when you return to the room, the sensor turns the lights on right away (as the switch is already closed), but in the other systems you would have to operate the switch again in order to turn on the lights. This second mode of operation is often mandated by energy saving codes; certainly it is where I live.

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## GeneC (Aug 28, 2017)

LasVegasJDub86 said:


> GENEC- Thank you for your post. You seem to be a very logical smart electrician. So tonight my foreman talked with the FA company and they denied every touching any of that. They said it was "exsisting" . Only problem is ,the lights in that classroom working jus fine pre-construction. And they are the only ones who are doing FA. It is an entire HVAC controls/Electrical( which my company is doing) and an entire FA upgrade . Which is another contractor. Ok so tonight I had a few extra minutes to look into this because the other 5 rooms look to have that same mini battery backup relay with no issues. So whoever wired up that one specific one is really love to give him a piece of my mind . GeneC: maybe you can explain to me exactly what they are doing here. Here is a classroom in which they have this relay wired . I guess I just want to understand the reasoning for this. Like I said these lights are not on a lighting contactor or any motion sensor. (See attached pictures) thanks everyone for your input . Like I said I am 30 years old. I went through the IBEW apprenticeship and have been doing electrical since (about 9 years) I have so much to learn and really love my job. Hardest part is dealing with others who are assholes or who treat me like a kid. That is the hardest part for me. I have to earn respect by showing what I can do.as you can see their FA goes into our lighting feed jbox that goes directly to the switch.


Jdub, Thank for the compliment. If I was in you position I would reconnect what you have to to get the lights working, you did your job. That relay is a motion sensor relay, although it can also be part of an energy management system. As far as the red MC Where's it go? Basically you just need to find out what all the extra crap is. Get the lights working and go from there. from the looks of thing there were a few hands in that mess. Maybe someone from the school can help and explain how it used to work or provide a set of plans. A good old switch works the best. Don't let it get you. Once you get lights working find out what they want or need and start from scratch. If it's FA co or EM let them do it. Could also be a component failure. The could be an interconnect between FA and lighting. You do not want the responsibility of doing that if you touch it you marry it and in the event of a failure it falls on you. My advice get lights working and leave the rest to the other DH's that mess with it in the first place. Gonna stick in your head - Kenny Rodgers, Know when to hold em and know when to fold em. I know it's hard but always CYA. Regards


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## GeneC (Aug 28, 2017)

Hey, just replied to your response without reading others If all was working and you found a motion detector and now its not working and no one touched anything then go back to what I said before. Easier to start over than trying to figure out what other people did. On a renovation of that scale if they are concerned about energy usage then they should install an energy management system while everything is opened up. Is that motion or IR hense the red MC Questions, Questions, Always Questions. Remember, wires don't disappear, re-connect themselves or change voltage under normal circumstances so KIS it.


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## LasVegasJDub86 (Sep 13, 2017)

GeneC- Thank you very much for your input. It is much appreciated. The lights are up and working . As far as the other crap, like you said we will let whoever is in charge of that to get it back working if need be. My boss is informed with everything that happened. We did our part . Moving on. I will most definitely keep in mind the things you told me. I was hesitant to even start trouble shooting this crap because of that concern about being blamed for issues that obviously had nothing to do with me. Lights are in proper working order , done deal. Thank you everyone for your advice . 
MUCH APPRECIATED!

-M


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## LasVegasJDub86 (Sep 13, 2017)

GENEC- also I am posting a new thread I am not sure in what section it is but I will figure it out. it is a code question I am currently studying the codebook just for my own knowledge and right now I am working on conductor ampacity, and had a question about it hopefully you will see my post and give me your input !


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## wiltavares135 (Sep 25, 2019)

One issue could also be that one light bulb between the last live light and the dead lights might be burnt


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## B-Nabs (Jun 4, 2014)

wiltavares135 said:


> One issue could also be that one light bulb between the last live light and the dead lights might be burnt


2 year old thread, and if you read the last couple posts the issue was resolved. 

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## readydave8 (Sep 20, 2009)

wiltavares135 said:


> One issue could also be that one light bulb between the last live light and the dead lights might be burnt


You think the lites are wired in series?

Wonder where LasVegasJDub86 is now?


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