# Lights wired to an emergency circuit won't energize



## acustom (Aug 8, 2011)

Hi.
I have a hotel for a client and when they experienced a momentary power outage of about 10 seconds the other day, they noticed that on one floor, 1/2 of the wall sconces weren't coming on.
The in house maintenance crew told me that these wall sconces are also connected to the emergency circuit from the generators. 
I checked the lighting contactor and it's working fine, w/ all circuits and corresponding switch legs energized.
No one seems to know where the emergency panel is and I looked everywhere for that and another time clock and contactor set up.. and didn't see anything.
I looked for drawings and they didn't have anything that pertained to this electrical installation.
The outage was so short that the backup generators weren't engaged. I'm not really sure how a backup generator transfer switch, if it malfunctioned, would effect only one circuit and not everything on that phase. 
I'm not saying that is the culprit, but it was an avenue that I pursued in trying to locate the source of the problem.
The voltage is 277/480.
I tried putting a tracer on one light to trace the circuit for an open or back to it's source, but I couldn't find a remote ground to attach to, so the tracer wasn't giving me reliable readings.
Has anyone had any experience with this sort of problem?
Thanks


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## bobbarker (Aug 6, 2015)

How many floors are there in this hotel? 
I ask because I am curious as to how the maintenance crew knows only 1 floor had half the lights working. So were all the lights on for all the other floors and how would they know in that in 10 seconds with no power?


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## telsa (May 22, 2015)

A remote ground is as near as any extension cord jacked into a receptacle.

I always have a cord cap wired to have green, white, black broken out ... wire nutted.

My ESP says the maintenance crew is HIGHLY involved in this puzzle, starting with it's impossible (for me) to believe that the EM circuit is feeding only one floor... unless the building is titanic.

Is the hotel fed by bus duct up to each floor?

Insufficient information to go much further. 

My ESP has its limits.

Check your neutrals, too.

Watch out for EM lights to be on 120 VAC NOT 277 -- even though the Service is at 480Y277.


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## acustom (Aug 8, 2011)

Thank you for your replies, I really appreciate it.
The hotel has 6 floors.
This is on the 5th floor.
The wiring to the lights is 12/3 MC cable.
Both circuits in the cable are not energized.
The first thing I thought of was the neutral as that could have blown out the lights. 
But the neutral is good. 
As I mentioned previously, both the circuit and the switch leg is energized at the contractor but the switch leg at the lights is dead as is another circuit traveling with it (as I mentioned at the top of this reply).
What other information can I provide you?


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## dmxtothemax (Jun 15, 2010)

Tell the maintenance staff to find the
emergency panel and then call you back.
Or otherwise they can pay you to find it.


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## glen1971 (Oct 10, 2012)

Are these lights fed from a panel that is only energized when the generator is running and online? Is so, have the maintenance crew start the generator and energize the panel. Verify that the contactor has pulled in for the emergency lights and walk them out.. See which ones don't work and repair as needed.

If not, and they should be on all the time, start following it back further and fix what's broke...


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## bobbarker (Aug 6, 2015)

Are these circuits controlled by a ELCU?


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## Wirenuting (Sep 12, 2010)

If the outage was so short that he generate never came on, how could any of the lights come on?

If the generator never came on during the 10 second outage and only 1/2 of the lights on one floor didn't work and the others did, that tells me that the other lights have a battery back up. 

if those lights don't work at all, find the emergency panel and go from there. 

A modern ATS will begin the generator start sequence as soon as the normal voltage dips to a preset value. The generator will start and come up to speed and voltage. But unless the ATS is set to commit to transfer, it will remain on the normal side of the voltage has returned to normal before the generator was ready to carry the load. 
Keep in mind that a three phase ATS that has both normal and emergency power available will not transfer until the in phase monitor, if programmed, senses that they are in fact in-phase. This can take seconds to minutes.


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## ELECTRICK2 (Feb 21, 2015)

acustom said:


> Hi.
> I have a hotel for a client and when they experienced a momentary power outage of about 10 seconds the other day, they noticed that on one floor, 1/2 of the wall sconces weren't coming on.
> The in house maintenance crew told me that these wall sconces are also connected to the emergency circuit from the generators.
> I checked the lighting contactor and it's working fine, w/ all circuits and corresponding switch legs energized.
> ...


If the gen didn't get on line of course the lights on the gen set circuits won't come on. The maint guys were probably on that floor when it happened. During the outage did the gen start? It could be as simple as utility came back on before the system transferred to gen power. You need to do a gen test that transfers the load to the gen. Since it's a hotel they would prolly frown upon a true power outage. So you do a transfer with utility power still available. That means you need a guy on each floor to monitor the lights. The lights on the emerg circuit should go off and back on in less than a second. Once the gen is on line, everything should be on. Explain to the customer that you can't say his back up works with out testing it. Hope this helps.


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## dmxtothemax (Jun 15, 2010)

Could it be that these lights that
Didn't come on do in fact get there
Power from the backup geeny ?
And because the geeny did not kick in
Then the lights also did not kick in ?


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## frenchelectrican (Mar 15, 2007)

Sorry to bring the topic up..

A) the generator(s) do have time delay so it will be controlled by ATS..

B) Check the setting on the ATS on the delay mode i know Hosptail is pretty on time window but motel it can be anywhere from minuim of 10 swconds to a minuite depending on the setup..

C) there ia no excuse to find the emergecy panels it should be marked someway so it can speed up the troubleshooting..

D) I will recomend that set up a day where the motel is not busy and actually do the unloaded test then do the loaded test to see the ats is working properly ( useally turn the uility source off ) then you can able find any panel is engerized by generator system and be aware you may find at least one downstep transformer is engerized by generator . go from there.


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## don_resqcapt19 (Jul 18, 2010)

frenchelectrican said:


> ...
> 
> B) Check the setting on the ATS on the delay mode i know Hosptail is pretty on time window but motel it can be anywhere from minuim of 10 swconds to a minuite depending on the setup..
> 
> ....


Emergency lighting is an Article 700 application and the generator is required to supply power to the emergency loads within 10 seconds. It does not change based on occupancy.


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## manchestersparky (Mar 25, 2007)

From What I read in the OP:
The wall sconces are normally lit at all times. ( as opposed to only when generator is running)
They are fed from an "emergency" circuit that is tied to the generator.
1/2 the 5th floor wall sconces are no longer lit


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