I’ve just started my training and I’m going through the electrical inspections course with limited electrical experience. I’ll likely need to do some extra work to gain the experience I need in this area, which I’m actually looking forward to… For now, I have a question regarding my service panel. This is a 125 amp Federal Pioneer Stab Lok panel with service lateral and I see that they’re listed as a typical problem panel for safety reasons. However, right now I’m wondering about the 3-wire system leading to the main breaker: two ungrounded conductors and what I’m assuming is the neutral, but shouldn’t it be insulated? Is a bare neutral permitted? Or have I completely missed the mark here?
Hi Jamie, I’m a new student as well. I’m wondering what this is? A goofy reflection or something else?
Can some please educate me? Is this somethings we should be on the lookout for? To my eye, it doesn’t look “normal” but I don’t have enough experience to actually determine that…
I went back to my panel and what you’re referring to is just the reflection. It’s hard to tell from the picture though and I wasn’t sure either. I had the power off when I took the picture, so the flash was the only light in the room.
No problem! I’ll be going back through the entire course when I’m done as well. For now, I’ve also been doing quite a bit of additional learning (here in the forum and articles as well as whatever else I can find that’s at my level, is relevant and is reputable) alongside the course to help cement the material in my brain.
If/when the main service panel, with a main disconnect, happens to be the same place that the grounded (neutral ) conductor is bonded to the grounding electrode, follow the EGC, then there is no problem mixing grounds and neutrals on the same bus bar, ‘as long as there is an appropriate number of conductors terminated under each lug.’
You have two (2) EGC’s entering the panel. Follow the EGC’s upstream.
The other acceptation, when there is a 4 wire feed into a remote distribution panel.
To expand on what Simon said, if you have a 3-wire MWBC there would be 2-120 volt circuits sharing a neutral. The two hot conductors cannot be on the same “phase” because that would possibly overload the neutral. If you look at the photo in post #4 you’ll see both a red and black conductor on a twin breaker that is attached to only one of the two “phase” buses.
What I meant by look carefully is that you would need to check and see if those two conductors (Blk, Red) are from the same cable, if they are then you have an issue.
Thanks for expanding. I’ve been reading up on MWBC for the past couple of hours and I’m having a difficult time making sense of things. I see what you’re saying in regards to that breaker having both a red and a black conductor and sharing a neutral. They are, indeed, from the same cable and they feed my kitchen. This twin breaker is also a double pole, 15 amp (hard to see in the picture).
My (new) understanding is that a MWBC with a double pole is ok if they’re on separate power supply so that both are tripped when either one has a fault. I also thought that spots on the panel directly above and below are on separate 120v power. If so, I’m not sure how they’re only on one bus. Part of my confusion also lies in the layout of my panel for a couple of reasons: the main breaker being fed directly from the two hots from the SEC without main lugs (different than all the diagrams I’ve been able to find); and the design with the buses running down the centre of the panel where the breakers stab into (all different than all the diagrams). Lastly, I’m assuming the silver bars running down the left and right sides are only brackets since the one on the left has no power feed at the top…
If you look at the square piece of metal with the odd shaped cut outs that is the bus. This CB is attached to only one of them. If it were removed and moved down so that it connected to two of the square bus stabs then one half of the two pole CB would be on one “phase” and the other half would be on the other “phase”. The fact that this is a 2-pole circuit breaker is correct because the NEC for a MWBC requires that both circuits are simultaneously disconnected.
