another star gournd question

digiblue · Post by **digiblue** » Fri May 09, 2008 10:22 pm

I have a question about whether I need to install another ground bar/rod at my panel location for this set up....

I have a 100amp service going underground into my studio from my 200amp panel in my home. The cable is an SER (3) 4awg and (1) 6awg GND conductor. At the studio panel I have a seperate (from the neutral bar) ground bar that is connected to the house ground via the SER cable AND connected to a local ground electrode outside the studio. I have all of the non-audio power and lighting terminated on one phase of the panel. For all audio outlets I have home run a 14/2 w/ gnd from outlet to panel location. I have several quadruplex receptacles that I ran 14/3 w/ gnd using the red traveller conductor as the second outlets dedicate ground (tagged green of course). My question is; in this configuration do I need to install yet another electrode and ground bar at the panel location for the home run outlets? It would seem that if each are home run I could ground them to my current ground bar (which is connected to home ground and an electrode) and maintain my star grounding. The only thing is that all of the non-audio circuits are also grounded to this bar. If I do need another bar/electrode it would still have to be connected to the current bar. Please advise.

Speedskater · Post by **Speedskater** » Mon May 12, 2008 11:15 pm

Is your studio in a different building than your house? If so, then yes it needs an additional ground rod.

digiblue · Post by **digiblue** » Mon May 12, 2008 11:18 pm

Yes, as stated the studio is in a pole barn. It does have its own ground rod connected to the ground bari n the panel as well as a connection to the house ground connected to the ground bar of the panel. What I am asking is do I need to install yet another ground rod connected to yet another ground bar at the panel location for the star grounded outlets even though they are all home run (outlet to breaker).

Speedskater · Post by **Speedskater** » Wed May 14, 2008 10:22 pm

So electricity from the power company goes to the house main breaker load center panel then to the barn sub-panel with a separate neutral bus and a ground bus (with a ground rod connected to the ground bus). Does the studio have yet another panel?

digiblue · Post by **digiblue** » Wed May 14, 2008 11:14 pm

I am feeding 100amps from the house panel to a 100amp panel in the studio. I've got the 2hot conductors connected to the 100amp main, the neutral connected to the neutral bar and the ground connected to a seperate ground bar in the panel. That same ground bar is also connected to a ground rod outside of the studio. This was required by the inspector. I have already had the building inspected as a pole barn earlier this year with just a few outlets and a couple lights (before turning it into a studio). I had some concerns about having the ground bar connected to two grounds (house ground and local electrode rod) but according to code in my area if the subpanel is more than 100' from the main panel it must be connected this way. My question is, in order to achieve star grounding on my audio outlets do I need to install yet another ground bar/electrode, which would also be connected to the main ground bar (by code). Given that all of the outlets are homerun romex each on there own circuit my first instinct is that an additional ground bar is not required to achieve the isolation needed for star grounding but I am not sure. If it is not sufficient my idea is drive another electrode and connect it to another ground bar inside of an additional metal box next to the panel. The new ground bar would be connected to panel ground bar via #6. Then all of the home run romex outlet circiuts would enter the new metal box where the grounds would terminate to the new ground bar. I would them run a piece of 1" conduit between the box and the panel where the hot and neutral conductors of eachcircuit would pass through into the panel and teminate to their respective breakers. It just seems a little redudndant to have to do this though to achieve the star grounding with the homerun outlets.

Speedskater · Post by **Speedskater** » Fri May 16, 2008 3:10 am

I'm pretty sure that code requires that the safety ground wires terminate in the same panel box as the hot and neutral wires. With only one sub-panel in the barn, I think that the one ground rod will be fine.