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Mike, Master Electrician
Category: Electrical
Satisfied Customers: 1425
Experience:  Licensed Master Electrician - OnQ Certified Data Voice Audio Video Installer
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I just built a small shed and ran power to it. After

Customer Question

I just built a small shed and ran power to it. After installing my lights and outlets, found that my two exterior flood lights trip the breaker. Have a 30-amp circuit dedicated just to the shed. With no other load on, floods will still trip the breaker. What could it be? The other lights and gfi's do not throw it.
Submitted: 1 year ago.
Category: Electrical
Expert:  Steven Parent replied 1 year ago.

Hello my name is ***** ***** will be happy to assist with your electrical questions.

What kind of flood lights do you have? Are you able to isolate each flood light, and see if it is only 1 that trips the breaker? It is most likely a ballast.

Customer: replied 1 year ago.
Can't really isolate them. Floods were cheap single bulb units I got at lowes. Removed a bulb and tried again and breaker trips immediately after hitting the floods switch. Rated for 150 watts each and put 75 watt bulbs in
Expert:  Steven Parent replied 1 year ago.

Ok, well then is sounds like you've got a short in the circuit. Does power run to the switch, and then outside to the 2 lights?

Customer: replied 1 year ago.
Single power source runs to two switches, blacks pigtailed, then to the two lights. One switch runs the interior lights, the other to the two floods.
Expert:  Steven Parent replied 1 year ago.

Ok, and have you checked the wiring/connections at the light fixtures?

Customer: replied 1 year ago.
Connections look secure inside the fixtures. Haven't opened back up the switches cause they were a pain to get all into the gang box the first time ��
Expert:  Steven Parent replied 1 year ago.

Does the wiring run from the switch, to the first light, and then over to the other light?

Customer: replied 1 year ago.
No, not chained. From the switch, a single line comes out to a junction, then to the lights separately.
Expert:  Steven Parent replied 1 year ago.

Ok. Well you have a short somewhere between the switch and the lights. So I would suggest starting at a light, undo it and separate the wires, and try the switch. If it still trips, do the same at the next light. If it trips again isolate the connections in the junction box. Could it be possible that a screw or nail has pinched a line?

Customer: replied 1 year ago.
I will give that a try. I guess it's possible that a line could be pinched as well-was kinda crude stapling the wire in place. If it's a wiring problem, I imagine I can get it sorted out. I guess my biggest concern was A) am I overloading the circuit (which I doubt); and B)does it sound like my amateur version of wiring was proper?
Expert:  Steven Parent replied 1 year ago.

Well you only have 150 watts of bulbs, so unless you have some major equipment running at the same time, you have enough ampacity. I would say most commonly lights off the same switch are chained. But that doesn't really matter. Sometimes a junction box makes more sense, as long as it is accessible you are fine.

Since you say that the breaker trips instantly after you flip the switch, it is a short. Check the wiring, you should find it somewhere, then you can repair it.

Expert:  Steven Parent replied 1 year ago.

Or you said the switches were a pain to fit into the box. I would pull it out as well to make sure the side screws were not in contact with anything.

Customer: replied 1 year ago.
Ok. In this case, the switch is between the two lights so a box made more sense than a chain. Also, for clarification, when I say "instantly," I mean that I switch them on, they come on for maybe half a second, then it trips. If there's a short, would they still light up for that split second before tripping?
Customer: replied 1 year ago.
Ok just got that one. Will do that as well.
Expert:  Steven Parent replied 1 year ago.

Let me know how it goes, and if you have any other issues.

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