Do I need 3 ground wires or is one enough ?

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Old 10-15-18, 06:09 PM
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Do I need 3 ground wires or is one enough ?

Running 3 Romex cables inside the wall to a junction box where they will be spliced and then from that box through PVC conduit will run as THHN wires up the garage wall until I get to the other end - where there is another box - from which I will go back to 3 Romex cables under the wall.

Obviously will run 3 pairs of THHN for neutral / hot but was wondering about ground wire.

do I have to run ground wire in the conduit for each individual run of Romex or can I tie the 3 grounds from Romex at one box into a single ground and then back to 3 Romex cables ?

Each circuit is 20AMP using 12AWG wires


thanks!
 
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Old 10-15-18, 06:19 PM
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Where multiple branch circuits run as individual conductors (e.g. THHN) together in a conduit, they can all share one ground wire, sized for the largest (amperes wise) of the branch circuits, here 12 gauge.

Yes, back to individual grounds when transitioning back to individual Romex cables.
 
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Old 10-15-18, 06:37 PM
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The size of the ground wire is based on the wire size of the other conductors, not the current. (amps) When the other conductors increase in size (IE: voltage drop) the ground wire also must increase in size.

As Allanj mentioned, yours will be #12.
 
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Old 10-16-18, 04:06 PM
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thanks guys - I am proud of myself....I was just guessing that I could use single run of ground wire based on my recollection of physics from 20+ yrs ago.....LOL

So it was good to get the confirmation from the experts
 
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