Clarification: Feeding 2 circuits via a 3-conductor wire (also know as a Multi-Wire Branch Circuit) is not normally done in new construction because it is not compatible with arc-fault and GFCI breakers, which are often required. This video is showing how to safely manage EXISTING circuits. In my case, my existing multi-wire branch circuits were a safety hazard and corrections were needed.
(1) Your diagram should not use Green to indicate a neutral, current carrying conductor. White is normally used for that in wire colors, but on your diagram, you could use a dashed line of some other color, and clearly label it as the neutral. Your diagram doesn't seem to show any equipment ground conductors at all. (2) The Multi-Wire Branch Circuit idea (sharing a neutral) was used in some situations years ago, but no more, since the advent of AFCI breakers, which are now required on practically every circuit in a residence. AFCI breakers require the neutral for EACH circuit to come independently back to the breaker. The MBC approach will immediately trip breakers, since the neutral current will not match the current on the black wire.
@@mikeheller1225 I totally agree on all points. Silver/gray would have been a much better choice (compromise) for representing neutral in the diagram. A dashed line would have been better too. As far as the MWBC, the big takeaway here is hopefully that if you already have MWBCs in your house, make sure they were installed safely! Mine were not. I was not required to update to AFCI, but I definitely needed to fix the safety issue. MWBCs (and their nuances) were unknown to me when I bought my house. Thankfully, I never got shocked when doing repairs, and hopefully I can help protect others by raising awareness.
@@reidthemanual White would be too hard to see on a white piece of paper, I didn't like the green but I thought you explained the reason for that color well, and you mentioned for clarity you omitted the EGC. All good. Grey would be ok for a neutral but mention that normally grey is only used typically on a 480Y277 volt system, where the L1, L2, L3 phases are brown, orange, yellow., and then grey for neutral. People have died before when a neutral wire was accidentally connected from a 480v system to a 208v system in the same building. Mike Holt has a good video on this and showed that accident as an example in one of his videos.
20 днів тому
Ur so wrong on every level it’s not worth correcting u smh. I guess that proves anyone can make a video my advice is forget everything he said
@@reidthemanual You're good. The only thing you were wrong about was at the very end of the video. When a MWBC is wired correctly, and the load is balanced, then no current at all flows on the neutral wire, it simply flows on red and black just like a 240 volt load with no neutral. In fact, you can disconnect the neutral wire at the panel on your example circuit and both room heaters will still work fine. Of course in real life, that wouldn't work very good, because no heater uses precisely the same amount of current due to manufacturing tolerances, and the wire runs are a different length etc etc. But if you shut one heater off, then both heaters will 'turn off'. The dangerous thing is if you open up one of the heaters to see what's going on, there's a big risk of shock because the heater is still energized, but no current is flowing. If you touched anything, then "You" become the neutral and that's not a good thing! The same danger occurs using a light switch to switch the neutral wire instead of hot to a light fixture. In the bad old days of knob and tube wiring this was done all the time, if it was convenient and saved on wire. That worked ok, but only because that used to be an ungrounded system so you couldn't get shocked unless you made contact with both a live and a neutral at the same time.
Clarification: Feeding 2 circuits via a 3-conductor wire (also know as a Multi-Wire Branch Circuit) is not normally done in new construction because it is not compatible with arc-fault and GFCI breakers, which are often required. This video is showing how to safely manage EXISTING circuits. In my case, my existing multi-wire branch circuits were a safety hazard and corrections were needed.
(1) Your diagram should not use Green to indicate a neutral, current carrying conductor. White is normally used for that in wire colors, but on your diagram, you could use a dashed line of some other color, and clearly label it as the neutral. Your diagram doesn't seem to show any equipment ground conductors at all.
(2) The Multi-Wire Branch Circuit idea (sharing a neutral) was used in some situations years ago, but no more, since the advent of AFCI breakers, which are now required on practically every circuit in a residence. AFCI breakers require the neutral for EACH circuit to come independently back to the breaker. The MBC approach will immediately trip breakers, since the neutral current will not match the current on the black wire.
@@mikeheller1225 I totally agree on all points. Silver/gray would have been a much better choice (compromise) for representing neutral in the diagram. A dashed line would have been better too. As far as the MWBC, the big takeaway here is hopefully that if you already have MWBCs in your house, make sure they were installed safely! Mine were not. I was not required to update to AFCI, but I definitely needed to fix the safety issue.
MWBCs (and their nuances) were unknown to me when I bought my house. Thankfully, I never got shocked when doing repairs, and hopefully I can help protect others by raising awareness.
@@reidthemanual White would be too hard to see on a white piece of paper, I didn't like the green but I thought you explained the reason for that color well, and you mentioned for clarity you omitted the EGC. All good. Grey would be ok for a neutral but mention that normally grey is only used typically on a 480Y277 volt system, where the L1, L2, L3 phases are brown, orange, yellow., and then grey for neutral.
People have died before when a neutral wire was accidentally connected from a 480v system to a 208v system in the same building. Mike Holt has a good video on this and showed that accident as an example in one of his videos.
Ur so wrong on every level it’s not worth correcting u smh. I guess that proves anyone can make a video my advice is forget everything he said
If you are saying that I should not have replaced the single-pole breakers with dual-pole ones, please give some specific reasons why.
@@reidthemanual You're good. The only thing you were wrong about was at the very end of the video. When a MWBC is wired correctly, and the load is balanced, then no current at all flows on the neutral wire, it simply flows on red and black just like a 240 volt load with no neutral. In fact, you can disconnect the neutral wire at the panel on your example circuit and both room heaters will still work fine. Of course in real life, that wouldn't work very good, because no heater uses precisely the same amount of current due to manufacturing tolerances, and the wire runs are a different length etc etc. But if you shut one heater off, then both heaters will 'turn off'. The dangerous thing is if you open up one of the heaters to see what's going on, there's a big risk of shock because the heater is still energized, but no current is flowing. If you touched anything, then "You" become the neutral and that's not a good thing! The same danger occurs using a light switch to switch the neutral wire instead of hot to a light fixture. In the bad old days of knob and tube wiring this was done all the time, if it was convenient and saved on wire. That worked ok, but only because that used to be an ungrounded system so you couldn't get shocked unless you made contact with both a live and a neutral at the same time.
@@brnmcc01 I really appreciate your comments.