Bonding Sub Panel to Main Panel Question

Submitted by G0BLINxKING t3_10lds90 in DIY

I finished building a detached garage on my property that previously had power ran from the main to a sub panel in the shed that has now been demoed and replaced. Do I need to fish a ground from the sub to the main so that the sub panel would be bonded to the main panel ground/neutral bar?

I have the wiring to the outlets and lights complete, but I am needing some help on this panel portion.

The previous set up in the shed was -- power coming in off the main panel (two hots and a neutral), and a bare copper wire from the sub panel into the ground and attached to a grounding rod, no ground back to the main. This is incorrect right? I need the sub grounded/bonded back to the main panel right? I have researched this before and found videos/articles of both ways being done and am still not sure what the correct way to go about this is.

**If I need to clarify anything, please let me know**

Photo taken before demo of shed. (Power was shut off at main before demo)

​

https://preview.redd.it/5tafyeoz1aea1.png?width=1170&format=png&auto=webp&v=enabled&s=95b541f6038f97e429f1ab904657fcc2fed73910

5

Comments

You must log in or register to comment.

ThisIsNotAFarm t1_j5w7oyo wrote

IIRC neutral/ground MUST NOT be bonded at the subpanel. The subpanel should have two bars, the neutral should be isolated. Ground in the sub should be connected to the main ground, the ground rod should be tied into the sub ground.

But you should definately check with a sparky

6

G0BLINxKING OP t1_j5wg86i wrote

Are you saying that the neutral in this photo (black and yellow) was improperly placed? I am glad I was right in my initial thinking then. I will need to fish a ground from this panel back to the main.

2

TheSearingninja t1_j5x2zje wrote

No the neutral is fine how it is. You will just need to make sure there is no bonding jumper that goes from the ground bar to the neutral bar in the sub panel. You don’t need to run a ground back to the main ground. What you have to do is to have the subpanel isolated between neutral and ground so that they are not bonded there. You can drive a ground rod near your subpanel and have that as your ground for your subpanel but again making sure your subpanel is not bonded with the neutral bar.

2

1feralengineer t1_j5w7h76 wrote

There are conflicting ways to do this because of differing circumstances (and sometimes because of various regulatory agencies "knowing" best).

When doing electrical work, if it isn't intuitive to you (because you understand it and have experience with it), you really should run your plan past someone who can look at it, including your local building inspector.

2

MisterElectricianTV t1_j5zbq2e wrote

It is now required to have a grounding conductor run back to the main panel from the subpanel. The ground and neutral are kept separate in the subpanel. This is to ensure that the circuit breakers will trip if there is a short circuit to ground. The resistance in the earth is too high to carry enough current back to the main panel to trip the breakers.

You also need a ground rod connected to the grounding terminal strip in the subpanel for lightning protection.

Many many years ago it was acceptable to just have the ground rod without a grounding conductor back to the main panel. That is no longer permitted in the National Electrical Code.

Remove that green screw in the upper right part of the neutral terminal strip

2