Shared Neutral Branch Circuits
Shared Neutral Branch Circuits
Pulling two homeruns in one shot, we can all agree is necessary with the cost of copper. Is it safe? Yes. Does it need to be fed on a two pole breaker if both circuits do NOT terminate on the same yoke 210.4(b)? No. For the safety of the idiot who thinks he knows what he's doing, should the electrician guarantee that if only one breaker (two single poles) is off, that the homeowner, handyman, drunk cousin, etc. doesn't get killed from contact with the load neutral of the remaining, live circuit? Why not? Other than when you are shutting off someone's life-support, when is it that much trouble to turn off one extra circuit?
The problem with installing a two pole breaker when terminating at seperate yokes is that when one breaker surpasses it's load capacity it has to throw a breaker that hasn't surpassed capacity. In other words, instead of tripping at 20 amps, it might take 24 amps to trip the troubled circuit.
This practice of using 3 wire when pulling homeruns was never an issue in Southwest Florida, an area that is more strict about safety than stereotypes on "Southern Construction" lets on.
I'm now in Northwest Georgia and while we pulled disposals and dishwashers with 12-3 in FL, we use 12-2 on the dishwasher and 14-2 to the disposal. The required size may only depend on the few factors we were taught on day 1 (draw, temp, raceway, etc.), doesn't the disposal count as a Small Appliance? Besides, having the capacity to add a small On-Demand or Insta-Hot without knocking down half the house sound good to you?
Anyway, as long as neither circuit is Arc-Fault or GFCI (they DO make 14-2-2 and 12-2-2), sharing the neutral should be accepted by code and common sense in all regions as long as the electrician has done the math and the gauge is within spec.
