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AssuredElectrical
AssuredElectrical, Master Electrician
Category: Electrical
Satisfied Customers: 4241
Experience:  Contractor-42+ Years in the ElectricalTrade
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My name is ***** ***** and... I am replacing a light fixture

Customer Question

Customer: My name is ***** ***** and... I am replacing a light fixture in our garage... There are 12 fixtures on the circuit... In the box, there are 3 sets of 2 wire romex
JA: Thanks. Can you give me any more details about your issue?
Customer: i need to know how to wire the 3 romex cables back together
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Submitted: 1 year ago.
Category: Electrical
Customer: replied 1 year ago.
The Romex cables all have black, white, and a copper ground wire. so at the lighting fixture, I need to use the black, white, and ground for the new fixture and connect the wires correctly to continue the string.
Customer: replied 1 year ago.
additionally, i was shocked by the white wires while the breaker was off. Could there me multiple circuits wired together?
Customer: replied 1 year ago.
i am sure the 3 black wires were wired together when I removed the light fixture.
Expert:  Kevin replied 1 year ago.

Hello and welcome to Just Answer. My name is ***** ***** I will be happy to assist you with your electrical question.

1) Do you have an AC voltmeter available to confirm some voltage measurements?

2) You were most likely shocked as the circuit is configured as a shared neutral circuit.

3) You don't remember how the original light was spliced?

4) Have all of the wire splices been removed? Any groups of wires that are still original and wire nutted together?

Customer: replied 1 year ago.
I remember the 3 black wires were all nutted together. I had to remove the entire box and replace it (long story) I do have a volt meter. What is my next step?
Expert:  Kevin replied 1 year ago.

1) Undo all of the splices on each wire color and spread each wire apart so they don't short. Turn the breaker ON. See if you can locate a constant 120 volt hot and white neutral in the box and label it as circuit feed using some white electrical tape and a Sharpie marker. Turn the wall switch ON/OFF to confirm if the hot wire is a constant hot or is a switched loop wire.

2) Measure each of the whites with the breaker in the ON position from white to bare copper ground. Do you measure any voltage on any of the whites?

3) How many of the whites were spliced together.

FYI.........next time before removing wire nut splices, you need to label the wires before removing everything.

Customer: replied 1 year ago.
I am pretty sure that originally only 2 whites were spliced together. I won't be able to measure the volts on the whites until tomorrow. Will you be available to answer questions then?
Expert:  Kevin replied 1 year ago.

No problem, I will be logged on the web site tomorrow, so just reply back to me on this same question and we can take it from there.

In the meantime, have a good evening and we'll catch up with you tomorrow..........Thanks.............Kevin:)

Customer: replied 1 year ago.
I just unspliced everything and there is no constant 120 volt.
Customer: replied 1 year ago.
The only way I measure any voltage is off of one white and a copper ground
Customer: replied 1 year ago.
I am pretty confident that that white wire was originally spliced into another white wire by itself
Expert:  Kevin replied 1 year ago.

Thanks for the replies.

1) If measuring 120 volts on a white to ground, then that white wire is acting as a hot wire and is not a neutral wire.

Did the white wire have a piece of black electrical tape wrapped around it to re-identify it as a hot conductor?

Customer: replied 1 year ago.
No it was not marked. This is a parking garage with multiple lights that operate off a photo cell
Expert:  Kevin replied 1 year ago.

1) Are the wires installed in EMT or Rigid Metal Conduit or was a flexible raceway or electrical cable installed?

Customer: replied 1 year ago.
They are romex with no conduit
Expert:  Kevin replied 1 year ago.

That explains why one of the white wires is hot. Code allows the white Romex wire to act as a hot wire if necessary.

Customer: replied 1 year ago.
Ok so you have any ideas how I should re wire it?
Customer: replied 1 year ago.
Is it as simple as all 3 blacks and all 3 whites together?
Expert:  Kevin replied 1 year ago.

1) No, one of the whites is being used as a hot wire. The other 2 whites are most likely neutrals. If splicing a white hot wire to a neutral wire, the breaker will trip due to a direct short circuit.

2) Label the white wire that is hot with some black electrical tape. Then splice the other 2 white wires together using a plastic wire nut.

3) The photo cell will contain a black, a red and a white wire. Can you confirm what wire color is spliced to the photo cell black wire? Possibly another black wire or a white wire?

Customer: replied 1 year ago.
There are no red wires.. All I have is 3 sets of romex each contains a black, white, and copper ground
Expert:  Kevin replied 1 year ago.

The photo cell should contain a red wire. Not the Romex cables.

What is the wire color that the photo cell red is connected too?

Customer: replied 1 year ago.
Again, there are no red wires
Expert:  Kevin replied 1 year ago.

What are the wire colors on the photo cell? 2 blacks and 1 white?

Customer: replied 1 year ago.
I am working with only 3 sets of romex. There is NO red wire anywhere
Expert:  Kevin replied 1 year ago.

You mentioned that you have a photo cell installed. I've never seen a photo cell that did not contain a red switched loop wire.

All photo cells contain 3 wires.....ie........a black, a red and a white. Somewhere you have a junction box where the 3 photo cell wires are spliced at. The red photo cell wire is the switched loop conductor that connects to the lights. Thus, a process of elimination to identify which of the light fixture box black wires is connected to the red photo cell wire. Thus the reason I was asking this.

I will opt out of the question and place it back to the open board. No need to reply back to me. You will be notified once another expert picks up the question. Thanks.

Expert:  AssuredElectrical replied 1 year ago.

Welcome. My name is ***** ***** would be glad to assist.

The very first thing you must do, is go directly to the photocell location, the inspect its wiring.

There is a red wire coming out of the photocell and you need to see what color wire is connected to that red.

see if it isnt connected to a white wire from a romex cable.

report findings and we can continue

Customer: replied 1 year ago.
I am pretty sure it is a black wire because I found 1 of the 3 black wires at the fixture to be hot when photocell is on. I will confirm at the photocell in a bit Thank You
Expert:  AssuredElectrical replied 1 year ago.

Very good.

Although you previously posted that only a white were was hot and nothing else?

Customer: replied 1 year ago.
I discovered there was a black wire that was hot when the photocell was activated. I have attached a picture of the photocell and do not see any red wires coming in from the photocell.
Expert:  AssuredElectrical replied 1 year ago.

Ok.

I do not see a photo cell in the picture.

Where is it located and can you get a picture?

Customer: replied 1 year ago.
The photocell is located on the back of the building but the wires from it going to this junction box. Do you want me to see if there is a red wires spliced into a black wire at the photocell? I'll get you a picture in a couple of hours thanks for your help.
Expert:  AssuredElectrical replied 1 year ago.

What needs to be done, is to identify the cable from the contactor junction box you posted a picture of, then identify which cable goes out to the lights.

Once you have identified the 2 cables, we can then determine how the fixtures were originally wired.

So, identify cable #1 from the photo cell to the junction box.

Identify cable from lights to the junction box

See how they are interconnected to each other and then we have the basic setup and can proceed.

Customer: replied 1 year ago.
Sounds complicated but doable. Since I have determined that one of the black wires is hot when photocell is activated and dead when it isn't, wouldn't that indicate that that particular is the feed from the photocell?
Expert:  AssuredElectrical replied 1 year ago.

Ok, first, I do not think that the lights are actually connected to the photo cell.

12 lights are too many to have on the photocell as a load.

That is why you have the large junction box and those 2 contactors.

The photocell turns on the contactors and they turn on the lights.

So, you will find that the photocell cable connects to power and then to the contactors, the light cable will connect to the contactors.

So, it is looking to appear, that the blacks connect all together at the lights as do the whites

But, that is why we find the connections first and do not begin to make guesses.

Customer: replied 1 year ago.
I can confirm that three black wires were wired together originally at the light fixture. I am going to look at the photocell now
Expert:  AssuredElectrical replied 1 year ago.

Ok, thanks.

If the 3 blacks were all connected together, it is most likely the 3 whites should also go together. Not a 100%, but certainly 95% of the time.

Customer: replied 1 year ago.
If one of the whites has constant power.. And one of the blacks has power activated by the photocell, wouldn't that be an issue down the line? Currently I have 2 of the whites spliced together (one is constant 120v) all 3 of the blacks, and one white not connected. I then have a light fixture connected with the black to blacks and white to copper ground. The issue I am faced with is the next light in the line will not light up but all other lights do..
Expert:  AssuredElectrical replied 1 year ago.

Ok, since we have no idea of how someone performed the installation, we need to make a test.

First, a white should not show power and should certainly not connect to other whites, if it does, as that is a dangerous situation.

Remove the white you state has power from the connection to a 2nd white, then cap it off.

Then connect the 2 remaining whites together and see if that makes the next light work.

Customer: replied 1 year ago.
I removed the constant hot white and capped it. Then connected the two remaining whites and same result. All lights come on with the photocell except for the next light past the fixture I replaced
Customer: replied 1 year ago.
I took the liberty to try all 3 of the whites together and i got the same result
Expert:  AssuredElectrical replied 1 year ago.

Ok, do this.

Disconnect all the whites.

Find the white that is inside the same cable as the Black that has 120 volts when the photocell turns on the lights.

Connect that one white to the white wire on the fixture.

Leave the other 2 whites disconnected and not touching each other.

Then test.

If you get the same result, you have a problem with that other fixture and need to get inside to find the problem.

What type of fixture is it? Make and Model is helpful.

Customer: replied 1 year ago.
I will do that tomorrow but I am testing the voltage on the fixture that isn't working so I eliminated the possibility of it being the fixture.
Expert:  AssuredElectrical replied 1 year ago.

please elaborate.

you can go to the fixture that is not working and measdure between the white and black wire connection from the romex cables and get 120 volts?

how many cables?

Customer: replied 1 year ago.
There is only one romex black and white going into the non working fixture. I cannot measure any voltage on it. It was working before I started this project
Expert:  AssuredElectrical replied 1 year ago.

ok, your connection at the other fixture is probably loose.

they need to be redone

Customer: replied 1 year ago.
I agree but with 3 sets of romex, I am still struggling with the configuration
Expert:  AssuredElectrical replied 1 year ago.

ok,

ok, your connection at the other fixture is probably loose.

they need to be redone

.all blacks together and all whites together

Customer: replied 1 year ago.
I tried all blacks and all whites together and the next fixture in line still isn't working
Expert:  AssuredElectrical replied 1 year ago.

Ok, by way of elimination, if the wires are connected well with good copper to copper contact, the next fixture is not wired from that fixture but from another location.

If the connections are not well made, which we see all the time from those not familiar with electrical, then anything downstream will not operate.

Since there are 3 whites and blacks, there is also something else connected.

So, disconnect the 2 whites and 2 blacks that are not the power and see what else is not operating.

Then by process of elimination, it may show that the first assumption is correct

Customer: replied 1 year ago.
Ok I will do that but the power I am getting is from one black and then copper ground wire.
Expert:  AssuredElectrical replied 1 year ago.

Oh, NO, that is not usable power

Must be a black and white or else the fixture will not work

Customer: replied 1 year ago.
The fixture is working from black and the white wire from the fixture is connected to the copper ground. Is that bad?
Expert:  AssuredElectrical replied 12 months ago.

Oh my, that is extremely dangerous for shock hazard and fire hazards.

The ground must be disconnected from the whites immediately.

If there is no voltage showing between the black and white of the same cable, you will have to trace the cable and find the break point or run a new one.

Ground wires are for your safety only and if connected to a white anywhere can cause a dangerous loop of unprotected circuits.

It is illegal to use a ground wire for anything other than grounding!!

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