subpanel 4-wire or service panel 3-wire?

I'm going to wire a detached garage and grounding the panel in the garage is subject to much confusion to me with respect to the 2002 NEC. The detached garage will also have telephone and coax cable coming from the house.
I was planning on running a 2/2/2/6 feeder cable from the main 200 amp panel at the house to a 100 amp subpanel with main breaker at the detached garage. Subpanel would have a floating neutral and separate ground bus. Also would sink a ground ground rod at the garage and connect it to the ground bus of the subpanel.
After researching this forum this appears the safest method to wire the garage panel.
The local permit office says I only need a 3 wire feeder, bond the neutral and ground at the garage panel, and sink a ground rod and connect to panel at the garage, In other words, he said this was just like another service panel since the garage is detached. I don't need a fourth ground wire from the main panel. He said the telephone/coax wire isn't an issue.
Sorry for the long explanation, but do I have a potential safety issue here if I go with the permit office advice and use 3 wire for the feeder cable?
What if I use 4-wire for the feeder? It would be contrary to what the permit office said. It meets NEC code, so technically it would pass inspection.
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The four wire versus three wire issue is a bit confusing. It appears to be interpreted that outbuilding subpanels should always be 3 wire plus local grounding rod, and "inbuilding" (in same building as main panel) subpanels should be 4 wire (separated ground and neutral).
Our code (CEC) _appears_ to draw a distinction between certain _types_ of outbuilding. But it wasn't consistently applied when our garage subpanel was inspected (the inspector signed off on it even tho it was done _both_ ways....).
All I can tell you is, provided you've explained your situation correctly to the permit office, the permit office is ALWAYS right, even when they're wrong.
Or something like that ;-)
--
Chris Lewis, Una confibula non set est
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mgershey wrote:

Is that copper or aluminum feeder cable? Just curious, because #2 is pretty big for copper.

The inspector is wrong. It's just like another service *if* there are no telephone/coax/water/gas/etc. return paths to ground between the house and the garage. (I'm wiring a garage panel right now using 3 wires, but I do not have any other wires or pipes connecting the 2 buildings.)
If the telephone and coax cable have a separate drop from the utility pole to your garage, they don't count and you can do a 3 wire electric feed, but 4 is still OK and probably preferred.
The way you are planning is correct.
Bob
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Thats The way I see it too. 4 wire feeder,isolated neutral, seperate ground, and a ground rod. The way you said. Tony D.

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Feeder cable is #2 copper. It's 55 feet from service panel to the garage panel. May have a welder at some point.

Yes, I tend to think they wouldn't look too favorably on me doing it "my way" with 4-wire. It's their way or no way...
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mgershey wrote:

Tell them your planning to run a gas line out there in the future. I'll try to look up the NEC paragraph about this later. The local inspector didn't like the way I attached a ground electrode conductor to my service conduit, and he told me to run it all the way to the service panel (which woulda been a major hassle.) I showed him in the code where the way I did it was specifically permitted; then we figured out a compromise that was better than what I had and as good or better than what he wanted. (I grounded the meter base, which was right above the electrode.)
If you can show the inspector what part of the code you're following, he's usually amenable.
#2 aluminum or #4 copper is plenty big for what you're doing if you want to save a few dollars. There's nothing wrong with using #2 though. I think #2 copper is good for 150A service.
Good luck, Bob
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