Neutral Connections and Ground Connections

[teal95]

Running wiring from my solar setup in the barn to a remote shed. 2 sets of conduit, 1 for AC and one for DC. Metal conduit ~50' across barn, then ~200' in plastic buried across to shed, then into metal conduit in shed to PV panels for DC and Romex for AC. Metal box for both transitions. Not having it inspected but want to follow code, as long as following code is the safe direction.

Should all the grounds be tied together in both metal boxes? A single ground is run through each conduit (DC and AC).

Should all the neutrals be tied together? Since I planned for 2 circuits I have 2 white wires through each section.

I wouldn't be surprised if it code is to keep them separate but this doesn't make a lot of sense as they're each tied together back in the breaker panel. As it's a remote panel ground and neutral are separated and I plan to keep them separated.

 

[timselectric]

Should all the grounds be tied together in both metal boxes? A single ground is run through each conduit (DC and AC).

Yes, and connected to the metal box.

Should all the neutrals be tied together? Since I planned for 2 circuits I have 2 white wires through each section.

No, each circuit should have its own (separate) neutral. You don't want parallel paths.

 

[teal95]

What's the problem with parallel paths? Not being argumentative, trying to understand.

 

[BentleyJ]

If one breaker is shut off then that entire circuit should be dead. However, if the neutral of the circuit you think is off, is shared with another circuit which is still ON then both neutrals could be energized, or not, depending on what appliances may be in use on the live circuit. Its Electrical Russian Roulette.
BTW, this is why any 240V breaker that per code may share a SINGLE neutral must have a handle tie so both sides of the breaker are Off or ON together.

EDIT: Re-Reading your post. There are only 2 circuits but 4 Neutrals. It is OK to use multiple parallel conductors on a single circuit as long as the connection points or lugs are suitable for multiple wire use or tandem lugs are provided.

 

[timselectric]

What's the problem with parallel paths? Not being argumentative, trying to understand.

1. There's no way to guarantee that the current will be balanced on both. Which could overload one.
2. It's a nightmare to troubleshoot , unless you know it was done.
3. Bentley, beat me to that one.
4. It's against code, for conductors smaller than #1/0 AWG. (For the reasons above)