just a dumb little question, ive seen this in a few boxs where they will use one neutral per three circurts, I myself like to give each circurt its own neutral. is this becoming or has been a way to save money. just wondering is all thanks joe
You asked if 'this' was a way of saving money....I'm sure that may play some part with this practice, but if you check out 310-15(b)(4)(a)  this will give a good reason for using the shared neutral. Example: if you tried to pull 6 circuits in a conduit using your one-neutral-per-circuit method you would have to derate the conductors 50% (Table 310-15b2a)... #12 THHN would only be rated for a 15A circuit ... using the shared neutral process you only derate 20%....in fact, you could get nine 20A circuits (using #12THHN) in one conduit (shared neutral method)vs. only 4 circuits using your method....god I hope I didn't blow my arithmetic!
Re: how many circurts per neutral#11925 07/26/0209:10 PM07/26/0209:10 PM
You have to realize that this is only an option under certain circumstances, it cannot always be done. For what you describe it would have to be a Three-Phase system and all on different 'phases' or 'legs'.
Re: how many circurts per neutral#11927 07/26/0209:24 PM07/26/0209:24 PM