Another 200.4 question

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DelightedInYahweh

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I am new to the electrical field and have many questions. Here is one of them. Thank you all for any guidance you may give.

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This image was part of an article talking about NEC 200.4 that started my mind wondering if what I was seeing in the field was violation of 200.4. I do see that there are #12 grounded with a #8 ungrounded in the image.

My question pertains to MWBC's I think. I do understand all that the NEC states in regards to what must take place at the point of origination in order to properly establish a MWBC. My question has to do if whether or not the follow two scenarios would be considered MWBC's thus fulfilling 200.4.

#1 We are working with 208/120 3 phase. There is a room of fluorescent luminaires and receptacles. Two ungrounded conductors and one grounded conductor was pulled in order to create circuits for this room. One for the receptacles and the other for the lighting.

#2 We have a retail room with multiple rows of fluorescent lighting. We pulled 2 black, red, and blue conductors. One for each row and then we pulled three grounded conductors. One conductor for two rows.

Would these circuits be considered MWBC's and be in compliance with 200.4?

Thank you for all your assistance.
 
I can't make out your diagram, but, in the event it does not, check out the definition: Branch Circuit, Multiwire in Art 100.

IN each of the scenarios you list, you have a grounded conductor and ungrounded conductors that fit the definition so in each case it is a multiwire branch circuit.

(In the diagram you have a somewhat unusual sitaution in that there would be no voltage between the ungrounded conductors as they are on the same phase, thus the higher rated (amperage) neutral.. I believe that is not allowed under the '11 Code.)
 
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Gus, hit the ctrl button and the + key and it will enlarge the screen. Use the ctrl - key to get it back. If you have a mouse with a scroll on it hold the ctrl and turn the scroll wheel.
 
In #1 you have a mwbc if the circuits are on opposite phases otherwise you have a problem.

#2 you have 4 hot conductors and 3 neutrals so somewhere you have to identify which neutral goes with which 2 hot conductor. The neutral with the 2 hots would be a mwbc

BtW- welcome to the forum
 
The installation in the image would only be permitted under Article 225. {225.7(B)}

In #1 yes you have a MWBC.

In #2 you could have a MWBC (BLK,RED,BLU,WHT) and a 2 wire circuit.
 
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