I have an old 60 AMP circuit to a stove/oven receptacle. The home run from the main panel to the stove receptacle is in a 3/4" Galvanized Metal Conduit pipe containing 2, #6 and 1, #4 wires and NO GROUND wire. The new stove/oven requires only a 40 Amp breaker (not sure of the potential maximum Amp draw for this appliance).

I would like to cut the existing conduit and wire then re-route it to a sub panel I will add to a wall in the center of the house in the utility room. This can be done by adding a 3/4" 90 and a short piece of conduit to the existing conduit for the drop from the pipe in the attic to the sub panel, or by using a junction box to terminate the conduit and convert to Romex. There will be enough wire to give me a straight run in the conduit from the existing main to the new sub panel if we stick with the conduit.

Next I want to add a metal junction box to the now open conduit coming from the stove, and then run a line from the new 40 Amp breaker in the new sub panel to the junction new box in the attic and then down to the stove. The attic allows standing up fully and the junction box will be near an existing receptacle box and easily serviceable should the need arise. This run too could be on conduit or preferably in romex.

Next I need to add a 15 Amp GFI breaker to the new panel for a new whirlpool bath that has a maximum draw of 7 Amps.

Not absolutely necessary but I would also like to add a 20 amp breaker to run wire to some hard wired, under cabinet lighting, total Amps used by these lights will be >3

If in the future if I need more Amps (doubtful but one never knows) I can then run a new larger wire from the main panel to the new panel and change the breaker in the main panel accordingly. Then I could add breakers as needed.

Questions are:

1- Can I use the conduit as the only ground from the main panel to the sub panel or do I have to run another wire for the ground?
a- If another wire is required would it be acceptable for it to come from a ground rod
Or a cold water line?

2- Is an accessible junction box legal in an attic?

Any other suggestions based on this scenario will be much appreciated?

Thanks for any help that comes!

My answers follow your questions in red;

1- Can I use the conduit as the only ground from the main panel to the sub panel or do I have to run another wire for the ground?

Yes, conduit is allowed to be used an an equipment grounding conductor, but locknuts must be rated, and certain conditions require bonding bushings.

It is standard in the trade last several years to use a green copper wire as an equipment ground, since conduit has potential for poor connections.

You can use 3-#8 THHN and 1- #10 Green THHN in the 3/4" conduit.

a- If another wire is required would it be acceptable for it to come from a ground rod
or a cold water line?

NO!

2- Is an accessible junction box legal in an attic?

Yes.

Any other suggestions based on this scenario will be much appreciated?

Thanks for any help that comes!


Hope this helps.

Thanks for the information, now I can move forward. I will test to confirm that the conduit is a good ground.

Thanks for the reply, now I can move forward on this progect.

Can you tell me how you plan to test the conduit?


Thanks for the information, now I can move forward. I will test to confirm that the conduit is a good ground.

You did not know it was allowed to be used as an equipment ground, I question that you know how to test it.

Any sub panel requires 4 wires back to the main panel... two hots, a neutral and a ground wire. Also at the sub panel the neutral and ground must be separated, and the neutral must not be bonded to the panel; only the ground buss is to be bonded to the sub panel.