Option One
New member
- Location
- Apple Valley, CA USA
Hi there,
I'm a new user. I have a rather urgent matter for inspection tomorrow. I need to confirm a code question on mulitwire branch circuits.
My company installed a PV system on a single family residence and it required a MSP upgrade. There are several 3 wire romex sharing neutral, the existing MSP had these terminated on 2 pole breakers, this is also how we've always interpreted the code and terminated the same way.
Another contractor came in and installed a generator in the middle of this and changed things, he states the this is not needed and re-routed one line from multiwire branch circuit to essential load panel and left the other line in MSP, leaving no way to disconnect or trip together. He stated that this is a a split wired device and not needed.
I read Mikes explanation of this code; my interpretation is that 3 wire romex, red, black and neutral is a multiwire by design, period. Regardless any raceway with 2 or more ungrounded conductors sharing grounded conductor, should automatically be on a 2 pole breaker or at least trip handles so they can trip and or be de-energized together. This would keep them on different phases so there is no potential to overload neutral, and we know that at least these two circuits will be de-energized at the outlet or switch box when tied breakers are off.
Am I interpreting this accurately or am i missing something, this guy claims to be an electrical engineer and says I should be looking at article 100, but when I do, it takes me back to 210-4. I appreciate some guidance on this one.
Question 2.
Also if he splits multiwire conductors and terminates one line in the transfer switch panel and leaves one line in the MSP, is this even allowed? 210.4 A states that multiwire branch circuit must originate from the same panelboard? It would appear to me that you would have to take all 3 conductors and ground wire to the transfer switch panel and use 2 pole breaker or trip handles to comply?
Scott
I'm a new user. I have a rather urgent matter for inspection tomorrow. I need to confirm a code question on mulitwire branch circuits.
My company installed a PV system on a single family residence and it required a MSP upgrade. There are several 3 wire romex sharing neutral, the existing MSP had these terminated on 2 pole breakers, this is also how we've always interpreted the code and terminated the same way.
Another contractor came in and installed a generator in the middle of this and changed things, he states the this is not needed and re-routed one line from multiwire branch circuit to essential load panel and left the other line in MSP, leaving no way to disconnect or trip together. He stated that this is a a split wired device and not needed.
I read Mikes explanation of this code; my interpretation is that 3 wire romex, red, black and neutral is a multiwire by design, period. Regardless any raceway with 2 or more ungrounded conductors sharing grounded conductor, should automatically be on a 2 pole breaker or at least trip handles so they can trip and or be de-energized together. This would keep them on different phases so there is no potential to overload neutral, and we know that at least these two circuits will be de-energized at the outlet or switch box when tied breakers are off.
Am I interpreting this accurately or am i missing something, this guy claims to be an electrical engineer and says I should be looking at article 100, but when I do, it takes me back to 210-4. I appreciate some guidance on this one.
Question 2.
Also if he splits multiwire conductors and terminates one line in the transfer switch panel and leaves one line in the MSP, is this even allowed? 210.4 A states that multiwire branch circuit must originate from the same panelboard? It would appear to me that you would have to take all 3 conductors and ground wire to the transfer switch panel and use 2 pole breaker or trip handles to comply?
Scott
