captainkirk
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unknown model and year. 1950's?
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Post by captainkirk on Jan 25, 2023 13:16:07 GMT -8
Hello there! So I have questions. About my original fixture for the kitchen overhead light and about my breaker box. I removed the original fixture when i bought the trailer and replaced it with a big-box-store overhead job. Now, i want to re-install it. However i need to back up my assumptions about it.
It has three wires. Two with bared ends and a third attached to the fixture. Am I correct in assuming that the shorter, bared wire attached to the switch is the "hot' wire and the longer, bared wire attached to the socket is the 'neutral', 'return wire'?. The circuit is completed via the wire that runs from the switch to the attached end on the fixture body? I will not be shocked when the circuit is completed through the fixture body? This is an AC, 110/120 volt fixture? I assume that this type of fixture is common--1 hot, 1 neutral, no ground, circuit completed through the housing--and i have nothing to worry but...well...maybe not, you know? I installed the breaker box three years ago and the photo shows it as installed and as used for that time. There is a 30 amp main breaker and two 15 amp feeder breakers. Each of those supply one device (1 outlet, 1 light fixture). I am backfeeding the main breaker with, as I remember, a 30 amp supply line. The wiring on the feeder lines is 20 amp thhn. Two of the bare wires that are hooked up to the ground bar are not connected on their other ends. Only one knockout has a grommet. I intend to fix those two issues soon. Backfeeding like this is proper and safe? I have searched forums and the internet in general and the consensus appears to be yes. The use of a main breaker looks like a subjective decision and it made sense to me. Also I have read about people using jumpers to connect all of their circuits. I am confused about when they are necessary but I don't think they apply to me anyways and want to ignore them. The backstabs are all connected to a single bar and so why bother? And it doesn't matter if i backfeed through the breaker or connect the main supply to one of the screw-in posts. Am i wrong?
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Post by vikx on Jan 27, 2023 14:40:36 GMT -8
"Backfeeding" has to do with the flow of power in one direction or another, so perhaps it is not the proper word? It often refers to a generator connected to a service box without a transfer switch, and is dangerous.
Your box looks very good. The main 30 amp in is connected to the main breaker, the neutral is on the neutral bar, and it is grounded. Grounds and commons/neutrals are on separate bars, with the neutral being isolated from the metal box. Congrats on doing a good job.
Each 15 amp breaker runs one circuit. Each circuit can run multiple light bulbs and/or outlets. Two 15 amp breakers is plenty for a small camper trailer. Connections from one line out to two are done in the electrical boxes, not in the breaker box. The breaker MUST protect the circuit. For instance, say you first go out to an outlet box on your cabinet: there will be a ground, neutral and hot coming into the box. You can then connect leads to another outlet box or light fixture. Electrical wing nuts are used for connecting inside the boxes. If you want to run a high amp machine (air conditioner) it is easiest to run it separate from the trailer.
The light fixture appears to be 12 volt only. The switch is on the negative (ground) side. This fixture will not work unless you have 12 volts to it. I'm not sure what you have now (sounds like 120 fixture) or where the 2nd bare wire goes on the 12 volt fixture. Does it connect to the socket? (there might be a wire coming out of the middle of the socket?)
Consider buying a DIY electrical book and study it. You're doing well so far, but there several little "tricks" that save time and keep things up to code.
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chriss
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Post by chriss on Jan 28, 2023 6:36:38 GMT -8
Agree too that the fixture is 12V with the switch on the ground side. The top wire will be your hot (+). The wire coming off the switch is your ground (-).
It really won't matter which way you hook it up. It will still function, but in this case, I wouldn't want the shell to be (+) all the time in case it contacts something metal in tbe trailer that is normally grounded.
The jumpers you are reading about are probably for 240v breaker panels with 2 hot lugs. In a 120v system, you can jumper between the lugs to utilize both bus bars.
The wiring looks correct, but I would plug unused holes and get some connectors or grommets on those other wires.
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WhitneyK
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'67 Shasta Compact
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Post by WhitneyK on Jan 28, 2023 15:10:16 GMT -8
That fixture wiring configuration goes against everything I understand about 12V DC (and actually that's quite a bit) For this to work, the socket itself would need to be isolated / insulated from the housing and the other switch wire connected to the outer socket for the bulb.
Reminds me of the old 6V positive ground systems.
If it were mine, I would disconnect the switch wire from the housing and wire it in series to the positive wire and ground the housing through the screw if possible or negative wire to the screw mount.
Positive from source connected to one switch wire, other switch wire connected to bulb socket wire.
Just my thoughts and opinions, didn't say they were good ones or without flaws...
Whitney
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chriss
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Post by chriss on Jan 29, 2023 9:06:54 GMT -8
In fundamental electric circuit, we switch the hot side, but you could switch the ground side. You don't do this in 120v house wiring due to safety and code reasons, but it's less critical in 12v systems.
The socket does have an isolated bulb lead and the socket housing is connected to the ground, so it works fine. For whatever reason, the manufacturer decided to switch the ground side and gave the installer an option of grounding through the housing or a separate lead if no housing ground was available.
This light wiring is similar to a traditional vehicle courtesey light circuit. The light is fed hot and circuit is completed through ground by the door switches.
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Post by vikx on Jan 29, 2023 13:33:22 GMT -8
I agree that having the socket wire hot out would work well in this situation. No chance of shorts if everything else is grounded.
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