I'm a 30 year Electrical Engineer who is rewiring my own residential house (which I've done before several times.) I don't have the NEC memorized so I'm asking for specific advice here.
The house has an appropriately sized panel in the garage, and most of the house wiring runs through a crawlspace, into the basement, and off to all the separate branches.
I'd like to run a large conduit from the garage panel through the crawlspace and into the basement for distribution using THWN. The conduit would feed into a large junction box, individual THWN conductors would be run from the panel to this box, then each would tie to romex for distribution. The question is, can one large (appropriately sized) conductor be used as a shared neutral to a bus bar in the junction box as it seems inefficient to run fifteen separate neutrals. There is actually already a previously added batch of similar circuits with four breaker fed branches that share one larger neutral, which passed inspection, but I don't know if that meets code today or if there is some upper limit to this concept.
Also, is there a maximum amount of separate circuits that can be run to one junction box regardless if the physical size of the box is large enough for x circuits? Yes, I know how to size the conduit for x THWN wires, but didn't know if there's code for number of circuits in a junction box, as the previously added 4 circuits I mentioned are stuffed into a pretty small junction box and it passed previously.
Alternately, I can switch out the panel for a smaller whole house breaker at the service entrance and run a full sub panel if this is allowed/preferred.
I'd like to have a proposal to submit which hopefully will meet NEC without having to go back and forth with the county fifty times.
Thanks.
The house has an appropriately sized panel in the garage, and most of the house wiring runs through a crawlspace, into the basement, and off to all the separate branches.
I'd like to run a large conduit from the garage panel through the crawlspace and into the basement for distribution using THWN. The conduit would feed into a large junction box, individual THWN conductors would be run from the panel to this box, then each would tie to romex for distribution. The question is, can one large (appropriately sized) conductor be used as a shared neutral to a bus bar in the junction box as it seems inefficient to run fifteen separate neutrals. There is actually already a previously added batch of similar circuits with four breaker fed branches that share one larger neutral, which passed inspection, but I don't know if that meets code today or if there is some upper limit to this concept.
Also, is there a maximum amount of separate circuits that can be run to one junction box regardless if the physical size of the box is large enough for x circuits? Yes, I know how to size the conduit for x THWN wires, but didn't know if there's code for number of circuits in a junction box, as the previously added 4 circuits I mentioned are stuffed into a pretty small junction box and it passed previously.
Alternately, I can switch out the panel for a smaller whole house breaker at the service entrance and run a full sub panel if this is allowed/preferred.
I'd like to have a proposal to submit which hopefully will meet NEC without having to go back and forth with the county fifty times.
Thanks.
