Hello, just wanted to say first of all I did search for an answer on this but its hard for me to get a straight answer out of some of the threads.
So here it is. I have an attached garage on my house with a pretty old sub panel(screw in fuses) that is fed by a 6/3 wire to give me 2 hots and the neutral. No ground.
I want to upgrade this to a breaker type sub panel with a few extra spaces so I can do a few more things in the garage. I would like to avoid running an entire new 4 wire feed to the sub panel and reuse as much as I can as the house panel and sub panel are very far apart.
I do have my well point about 10' from the sub panel in the garage as well.
So here is the list of questions:
1.) Can I use the 6/3 wire currently feeding the fuse box?
2.) If adding a ground is needed can I run a ground wire to the well point from the sub panel? Just FYI the MAIN house panel is grounded to the well point already as well as two ground rods.
3.) How would I configure the sub panel as far as bonding or not, adding a seperate ground bar in it or connecting ground and neutral wires to same bar.
The problem I see is the neutral. A 2 wire with ground cable usually has an uninsulated EGC that can't be used as the neutral (plus it will usually be smaller than the ungrounded conductors) and there is no provision to run a neutral outside of the cable or raceway. If, by some strange reason, they did run a 3 wire (red, black white) cable with all conductors insulated he might be able to establish his EGC with a separate wire.
As for just grabbing the grounding electrode conductor at the well point, You might be able to make a case for it.
250.130 Equipment Grounding Conductor Connections. Equipment grounding conductor connections at the source of separately derived systems shall be made in accordance with 250.30(A)(1). Equipment grounding conductor connections at service equipment shall be made as indicated in 250.130(A) or (B).
(A) For Grounded Systems. The connection shall be made by bonding the equipment grounding conductor to the grounded service conductor and the grounding electrode conductor.