I recently experienced monumental problems following neutral failure in my underground electrical supply. As a result, I have had the main breaker panel replaced because it appeared the main breaker was over stressed and an installed surge breaker had melted into the panel.

I am concerned about grounds though the power co. engineer claims better grounds would not likely have prevented problems (LOTS of things burned out!).

Power comes in to a main disconnect which is grounded to a driven ground rod. 3-wire service entrance cable feeds the main 200A panel in the house (about 50' running underground). This panel is not bonded and is grounded via a second ground driven rod at least 40' from the main disconnect. Subsequent to installation of the main panel, #6 ground wire was run through conduit during construction of an attached garage. This could be used to tie the ground at the main disconnect to the ground in the main panel but my electrician thinks this not a good idea.

Should I have this ground tied to the ground in the main panel? Should I drive a second ground rod and tie it to the existing ground rod for the main panel.
When the power co. replaces my failed underground service, I can install another ground at the main disconnect to a well casing. Would this be a good idea?

(note, the main panel is really a sub as it is being fed from the main disconnect). Thanks in advance for any help and advice.

I am having a hard time follwing what is where. What areas are attached and what are detached from each other?
Where is the main disconnect?
Where is the panel compared to the disconnect? Where does that 50' come into play?

I have to say, you have a very misinformed, yet very common, idea of what ground rods do.
Ground rods DO NOT "ground" anything, if you can believe it. That have absolutely no bearing of the functionality of the electrical system, and they serve NO purpose in clearing faults and tripping breakers.

I have to say, you have a very misinformed, yet very common, idea of what ground rods do.
Ground rods DO NOT "ground" anything, if you can believe it. That have absolutely no bearing of the functionality of the electrical system, and they serve NO purpose in clearing faults and tripping breakers.

Stan not my post but please ellaborate. What do ground rods do than?

As always your insight is apprecated

The Neutral opening up is what did the damage,
I don't think ground had any effect.

I apologize that my original question was not perfectly clear. I am also well aware that the problems were caused by the failed neutral but in the process of replacing the "main" breaker panel I wanted to reevaluate my grounding system and upgrade it if advisable. Let's start over.

A main fused, 200A disconnect is fed via underground cable ( the one which failed). This disconnect is grounded via a driven rod. The first question is whether I should consider upgrading this ground by running a ground to a well casing which I will be able to do when the power company fixes their underground cable? (neutral bonded at this disconnect).

When originally installed, the main breaker panel in the house was fed with about 60'-70' of 3-wire service entrance cable run underground from the main disconnect. I believe this to have been a mistake as no ground was provided. Instead, a second ground rod was driven in a different location to ground this panel. Finally, when I constructed a garage, I ran a conduit between the main disconnect and the breaker panel. At present, there is #6 ground conductor in this conduit.

My electrician feels this ground conductor should not be used. If I wish to improve the ground at the main panel, he advises only driving a second ground rod. So this is the second question. Should I tie the main disconnect and main breaker panel grounds together with the #6 conductor or leave the breaker panel grounded only via the driven ground? If tying them together is a good idea, should I pull something larger in the conduit (#4?)? (reminder, neutral is not bonded in this panel as per code).

I believe it is true that using the ground in the conduit is actually a code violation because it is not "contiguous" with the conductors in the 3-wire cable. My goal is only to get the best ground possible.

I appreciate the significant knowledge of stanfortaman in his posts. My understanding is that grounding systems are primarily for safety purposes but at higher frequencies (above 60Hz) may also provide for signal references and lightning protection. In any case, I believe NEC requires grounds and, hopefully, with a low impedance to "earth ground." I am much less clear on the actual aspects of providing good grounds and it is not clear to me whether "better grounds" might have alleviated some of the wild voltage swings resulting from the neutral failure.

I should also have acknowledged the expertise of Stratmando in my update. As a new member, it is comforting to know that there are experts willing to share and help.