sub panels

[Cliff Rohrabacher]

I just installed a Siemen's sub panel using a Siemen's main 100 amp box as the sub. It came with a 100 amp breaker in place and a little box of 8 or so 20 amp breakers - - -and - - - nothing by way of a ground bus bar.

It's my preference ( and I believe Code) to never bond the Sub-Panel's supply Ground to the Sub-Panel's supply Neutral when the Sub is inside the main building. Which means the ground is swinging in the breeze.

That is absolutely wrong~!!

The Siemens' box has a little tag in it that instructs you to BOND the Neutral to the Ground. However I rather suspect that this applies only if the box is being used as the Main Panel.

Attaching the Supply Ground wire it to the sub panel wall is silly, 'cause I gotta strip paint to get a ground connection to the steel from which the box is made. And that'll still leave me with the issue of where to connect the ground wires from the breakers.

The Option that appeals is to get a ground buss bar and ground to that. I simply don't see a better way to do this. The grounding wire passes right over head so I can run a heavy ground wire right to the main ground too.
Any ideas?

************Another issue. **************
I have an older sub in another part of the house which is fed by #4 copper with BX shielded cable. The BX shielding is the ground and it is really old and I don't trust the old BX connections so I ran a heavy copper from the ground buss (that box has one) to the heavy grounding wire that happens to pass right overhead.
I wonder if the code guy will look funny at that.

[Jim O'Dell]

Note that I'm not an electrician, but I played one in my own shop-with help! The reading I have done says that the sub panel needs separate ground and neutral wires from the main box to the sub panel, and the sub panel neutral not bonded to the box.
My help on my electrical came from from fellow SMCer Tommy Curtis. I had failed to ground my neutral to the box and he noticed it in about 2 seconds! (Separate feed from the pole so it is a main box, not a sub box.)
I'm sure a true electricial person will pop in here and verify this post, or correct it. Jim.

[jeremy levine]

On your second issue , I think it violates the "letter" of most codes.


If you have the box , the breakers and the wiring I think an electrician could whack it together ( in to code compliance ) in short order.

[David G Baker]

Another non licensed electrician.
In the main box the neutral and ground are joined in the box.
In a sub panel they are not.
If 220 volts are run to a separate building isolated from the building that has the main box in it and 4 legs are run, (2 hot legs, 1 neutral and one ground) the neutral and ground are not joined in the isolated buildings box.
If 220 volts are run to a separate building isolated from the building that has the main box in it and 3 legs are run, (2 hot legs and 1 neutral) the neutral and the ground are joined in the isolated building box. A code grounding is needed. I use 2 8 foot ground rods 6 feet apart driven into the earth and joined by #6 wire or larger. This varies from community to community depending on the local code enforcing agency. In this case you do not want to run other wires that may be connected in any way to the main house ground system, such as telephone, cable, etc.
Every time this topic is mentioned on a forum it usually stirs up a hot debate.

[Cliff Rohrabacher]

On your second issue , I think it violates the "letter" of most codes.

Hmmm. You think running a bare ground from a sub to the main ground wire may violate code?

[Jim O'Dell]

Cliff, I meant to say also that I believe you will need separate ground and neutral buss bars. Just tie the main box buss bars to the sub buss bars via wiring. Jim.