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AssuredElectrical, Master Electrician
Category: Electrical
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Experience:  Contractor-42+ Years in the ElectricalTrade
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I have wired 3 sets of overhead fluorescent light fixture in

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I have wired 3 sets of overhead fluorescent light fixture in my new shop. I wired the first light to the second and then connected a 12/3 mc cable to them and ran it to the gang box. This is repeated with two other sets of lights each having it's own run to the gang box. I then ran a line from the panel to the gang box. There I connected all of the white wires. I then connected pigtail wires from each single pole switch and connected them with each ground wire from the three lights as well as the panel wire ground. The black wires from each light run is connected to the top of the switch and black wire pigtails are connected to the panel black. When applying power to the circuit it trips the breaker or in this case the GFCI which I'm drawing temporary power. I'm using wire nuts on all connections and can't figure out what I have done wrong. Do you have any ideas?

AssuredElectrical :

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

AssuredElectrical :

Lets recap and verify the information.

AssuredElectrical :

Sounds like you have 6 light fixtures total. They are split into 3 sets of 2 to work with their own switch?

Customer:

correct

AssuredElectrical :

so, 2 lights per switch?

Customer:

yes

AssuredElectrical :

ok, what wire is between the 2 lights?

Customer:

i used the same wire on everything and that is a 12/3 mc cable

AssuredElectrical :

Ok, thanks

AssuredElectrical :

so, you have one 12/3 from each set to the switches and also a 12/3 from the power source to the switches?

Customer:

yes

AssuredElectrical :

ok

AssuredElectrical :

at the switches, you joined all the whites from all cables together with a wire nut?

Customer:

yes

AssuredElectrical :

and all the black wires from the 3 - 12/3 cables connect to their respective switches?

Customer:

yes - does it matter if the power (black is on the bottom or top of the switch?

AssuredElectrical :

no, doesnt matter

AssuredElectrical :

so, you took the black wire from the power cable and connected 3 short black wires to it and used those to connect to the other screw on the switches?

Customer:

yes

AssuredElectrical :

ok, when you say 12/3, is it just a black,white and ground?

Customer:

yes

AssuredElectrical :

ok, so we are on the same page, that is 12/2 cable with ground. Actual 12/3 has a red wire also

Customer:

okay - i'm sorry about that. it is black, white and a ground

AssuredElectrical :

that is fine, not a problem, just verifying so I know the wires we have

AssuredElectrical :

all of these lights are fluorescent fixtures, correct? And you connect black to black and white to white on the ballasts?

Customer:

yes- the type of lights that I have came with a male/female connector where you could place the stripped wire into it to make the connection.

AssuredElectrical :

Ok,

AssuredElectrical :

at the power source, this is a GFCI receptacle or breaker?

Customer:

receptacle

AssuredElectrical :

ok, how many wires were in the receptacle before adding this new cable?

Customer:

when troubleshooting this I used a male plug with a cord that I cut off of an outlet strip and wire nutted that to the power side of the circuit

Customer:
Metalux 97-1/4-in Fluorescent Strip Light is the lights that i'm using
AssuredElectrical :

so you put a male cord end and attached to the wires in the mc cable?

Customer:

yes to the end that would eventually be connected to the panel

AssuredElectrical :

ok

AssuredElectrical :

you connected color to color, yes?

Customer:

yes

AssuredElectrical :

ok

AssuredElectrical :

and the GFCI resets after you unplug the cable?

Customer:

yes

AssuredElectrical :

Are all the switches mounted in the box? or hanging?

Customer:

right now they are mounted

AssuredElectrical :

Ok

AssuredElectrical :

First thing to do: Pull all the switches out of the box and let them hang to be sure no wires are touching each other. Then try the GFCI for power. Second: If it still trips, then disconnect the black wire from the 3 pigtails and try again.

Customer:

i had taken all of the switches out and tried to troubleshoot one circuit at a time. When doing so I got all of the lights to work (after cutting a factory connector off and wiring direct to the ballast

Customer:

okay that is what I was going to do next. do you recommend using black tape around the wire nuts?

AssuredElectrical :

ok, so you had them working?

Customer:

yes - i connected power to each line separately and they worked

AssuredElectrical :

how did you do it separately?

Customer:

using the same wire that i used to connect to power

AssuredElectrical :

ok, so you connected the power cable to each light cable at the switch box and tested them one at a time?

Customer:

do you think that there is too much amp draw on that cord?

AssuredElectrical :

GFCI do not work like a breaker, no

AssuredElectrical :

was my previous question correct?

Customer:

the cord is connected to an extension cord that is plugged into a GFCI outlet

AssuredElectrical :

so you connected the power cable to each light cable at the switch box and tested them one at a time?

Customer:

yes

Customer:

I have to leave my office to run an error - do you have any other ideas?

AssuredElectrical :

Pull all the switches out of the box and let them hang to be sure no wires are touching each other. Then try the GFCI for power. Second: If it still trips, then disconnect the black wire from the 3 pigtails and try again., If it still trips, there is something wrong in the MC cable, possibly a wire was knicked when cut (it happens often with the hacksaw). If it doesnt trip, add one switch at a time to see which run is tripping the GFCI. Again, may have a knicked wire and touching inside the meatl sheath.

AssuredElectrical :

It is easy to have a small knick in the MC cable at the end and it only touches when you move it around, we see this often

Customer:

I'll give that a try - thank you

AssuredElectrical :

you conenctions are perfect with the wiring

AssuredElectrical :

nothing to do with your wiring format, something else is happening

AssuredElectrical :

try all that and you come back here anytime to carry on if needed. This is here to stay and will not go away.

AssuredElectrical :

bookmark this page for easiest access or look under a link on your page for "My Questions"

Customer:

I used a


SW BX MC ROTARY CUTTER WITH LEVER to cut all of the mc
Customer:

thank you and have a great day

AssuredElectrical and other Electrical Specialists are ready to help you

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