Denray Posted February 18, 2017 Report Share Posted February 18, 2017 200 amp main panel outside on post has 3 wire feeder to garage 200 amp sub panel. Should there be an equip ground there too? Click to Enlarge 88.56 KB Click to Enlarge 36.22 KB Click to Enlarge 50.17 KB Quote Link to comment Share on other sites More sharing options...
Marc Posted February 18, 2017 Report Share Posted February 18, 2017 Where's the main disconnect? Are those two breakers in the photo fed by a tap or by a branch circuit coming from the breaker panel situated elsewhere? The neutral can be bonded to earth anywhere between main disconnect and breaker panel. Grounding conductor starts at that bond and runs downstream from there. Marc Quote Link to comment Share on other sites More sharing options...
Jim Katen Posted February 18, 2017 Report Share Posted February 18, 2017 When that service was installed, you could feed a sub panel in a separate structure with only a 3-wire feeder. Quote Link to comment Share on other sites More sharing options...
Denray Posted February 18, 2017 Author Report Share Posted February 18, 2017 What's the safety problem in this case? Quote Link to comment Share on other sites More sharing options...
Jim Katen Posted February 18, 2017 Report Share Posted February 18, 2017 What's the safety problem in this case? If it was done "correctly" at the time, there should be a grounding electrode at the post and another at the garage. If the neutrals and grounds are tied together at the garage (as they should have been according to that era's requirements), then you'll probably get current travelling through the earth between the garage GES and the post's GES. In some cases people or animals might actually become part of that path. That's one of the reasons why the rule changed. Quote Link to comment Share on other sites More sharing options...
Denray Posted February 18, 2017 Author Report Share Posted February 18, 2017 They separate at the garage. So, cant clear a ground fault that way? Click to Enlarge 65.22 KB Quote Link to comment Share on other sites More sharing options...
Charlie R Posted February 18, 2017 Report Share Posted February 18, 2017 Is that a GEC coming off the bottom of the grounding bar that is attached to the backside of the panel? I believe I see a thicker copper line at that location. Quote Link to comment Share on other sites More sharing options...
Marc Posted February 18, 2017 Report Share Posted February 18, 2017 What's the safety problem in this case? If it was done "correctly" at the time, there should be a grounding electrode at the post and another at the garage. If the neutrals and grounds are tied together at the garage (as they should have been according to that era's requirements), then you'll probably get current travelling through the earth between the garage GES and the post's GES. In some cases people or animals might actually become part of that path. That's one of the reasons why the rule changed. Going off course here a little but the impression I get is that the rule was changed in the 2002 NEC (250.32) because incidental parallel conductive paths between the two buildings (steel water pipe, steel conduit, etc) would end up carrying neutral currents if the neutral were bonded to the grounding system in both buildings. It's the same problem that happens when an EGC is bonded to the neutral in two locations in a house: neutral currents will end up flowing thru the much smaller EGC and overheat it. Electricity normally flows in the Earth for a variety of reasons. It's why some expansive industrial sites have multiple ground rods inserted at points along a long circular path on the property and are joined together along with all metallic structures and electrical systems onsite. It equalizes the local electric potentials of the Earth. JMHO. Marc Quote Link to comment Share on other sites More sharing options...
Marc Posted February 18, 2017 Report Share Posted February 18, 2017 They separate at the garage. So, cant clear a ground fault that way? Click to Enlarge 65.22 KB Right. At least I think so. 250.32 B (exception 3) says that installation shouldn't have any GFCI devices in the garage. Marc Quote Link to comment Share on other sites More sharing options...
Tom Raymond Posted February 18, 2017 Report Share Posted February 18, 2017 That will all be brought to modern standards when that rotten contaminated equipment is replaced. That would be my call anyway. Quote Link to comment Share on other sites More sharing options...
Denray Posted February 18, 2017 Author Report Share Posted February 18, 2017 Thanks everyone. More than 6 breakers at the garage sub, too. Quote Link to comment Share on other sites More sharing options...
Jim Katen Posted February 18, 2017 Report Share Posted February 18, 2017 They separate at the garage. So, cant clear a ground fault that way? Click to Enlarge 65.22 KB If they're separate, yes, the equipment grounding conductors won't do their job very well. Quote Link to comment Share on other sites More sharing options...
Jim Katen Posted February 18, 2017 Report Share Posted February 18, 2017 What's the safety problem in this case? If it was done "correctly" at the time, there should be a grounding electrode at the post and another at the garage. If the neutrals and grounds are tied together at the garage (as they should have been according to that era's requirements), then you'll probably get current travelling through the earth between the garage GES and the post's GES. In some cases people or animals might actually become part of that path. That's one of the reasons why the rule changed. Going off course here a little but the impression I get is that the rule was changed in the 2002 NEC (250.32) because incidental parallel conductive paths between the two buildings (steel water pipe, steel conduit, etc) would end up carrying neutral currents if the neutral were bonded to the grounding system in both buildings. It's the same problem that happens when an EGC is bonded to the neutral in two locations in a house: neutral currents will end up flowing thru the much smaller EGC and overheat it. Actually, the whole parallel-conductive-path-between-buildings concept was introduced in the 1999 edition. It was abandoned in 2008. The issue isn't so much one of overheating as having current in unexpected places. Electricity normally flows in the Earth for a variety of reasons. It's why some expansive industrial sites have multiple ground rods inserted at points along a long circular path on the property and are joined together along with all metallic structures and electrical systems onsite. It equalizes the local electric potentials of the Earth. JMHO. Marc True. But they install those systems because electricity flowing through the earth is not a desirable thing. Quote Link to comment Share on other sites More sharing options...
Jim Katen Posted February 18, 2017 Report Share Posted February 18, 2017 They separate at the garage. So, cant clear a ground fault that way? Click to Enlarge 65.22 KB Right. At least I think so. 250.32 B (exception 3) says that installation shouldn't have any GFCI devices in the garage. Marc Actually, that's talking about ground fault protection of equipment (GFPE), which is almost certainly not going to be present in this garage. It's fine to have GFCIs in there. Ground faults aren't going to be cleared because there's no low impedance path back to the neutral. Quote Link to comment Share on other sites More sharing options...
Jim Katen Posted February 18, 2017 Report Share Posted February 18, 2017 That will all be brought to modern standards when that rotten contaminated equipment is replaced. That would be my call anyway. Mine as well. Big time. Quote Link to comment Share on other sites More sharing options...
Jim Katen Posted February 18, 2017 Report Share Posted February 18, 2017 Thanks everyone. More than 6 breakers at the garage sub, too. Not an issue in a sub panel. Quote Link to comment Share on other sites More sharing options...
Denray Posted February 18, 2017 Author Report Share Posted February 18, 2017 So, having the post up the driveway for the main breaker doesn't make the house like a separate building that needs its own 6 or less breaker deal? Quote Link to comment Share on other sites More sharing options...
Jim Katen Posted February 18, 2017 Report Share Posted February 18, 2017 So, having the post up the driveway for the main breaker doesn't make the house like a separate building that needs its own 6 or less breaker deal? Sorry. You're correct. It needs 6 or fewer disconnects. Quote Link to comment Share on other sites More sharing options...
Denray Posted February 18, 2017 Author Report Share Posted February 18, 2017 OMG, I figgerd something out for once. [:-dunce] Quote Link to comment Share on other sites More sharing options...
Marc Posted February 19, 2017 Report Share Posted February 19, 2017 OMG, I figgerd something out for once. [:-dunce] Moving up in the world! Marc Quote Link to comment Share on other sites More sharing options...
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