JD, First of all, I commend you for taking the time to ask hard very legimitate questions and trying to GET THIS RIGHT, safe and NEC proper as most of the untrained but still "know it all" Billy Bobs of the world dont care as long as it works and pooh pooh the NEC and trained experienced professional electricians and engineers.......Also, unlike some, you ask advice and follow up questions AND ACTUALLY READ AND LISTEN to responses. As I always say, however, dont just take my word for it, consult the NEC and more current professionals AS IM LONG RETIRED AND RUSTY. Still, I give what I recall as the best professional (albeit rusty) advice and try my best to help protect life and property. Im here to try n help NOT feud lol answers
I CAN TELL YOU WHERE YOU WENT WRONG but dont take offense as you're at least trying to GET IT RIGHT and are rightly concerend for your own as well as the buildings safety.....
You done good by running 4 wires (2 Hots, Neutral, Equipment Ground) to those out buildings
BUT AT THOSE PANELS YOU DO NOTTTTTTTTT I REPEAT DO NOTTTTTTTTTTTTT BOND NEUTRAL BUSS TO EQUIPMENT GROUND BUSS, THEY ARE TO REMAIN SEPARATE AND ISOLATED. When you bond them you defeated the whole purpose of running 4 instead of only three wires in the first place like was done days past !!!!!!!!!!!!!! Some panels suitable for use as Service Entrance have a tie bar to conenct Neutral and Ground busses when they are the main panel but the ability TO NOT ATTACH them when used as a sub,. Of course, some panels intended ONLY for mains have but one common buss where BOTH Neutrals and Grounds attach.
NOTE 1, I'm sure youre already aware the main service entranced Panel DOES BOND THE NEUTRAL BUSS TO THE EQUIPMENT GROUND BUSS but once more DO NOT DO THAT AT THE SUBS, those 2 busses are kept separate and electrically isolated.
NOTE 2, HOWEVER, as its a non current carrying metal enclosure, the sub panels case/frame DOES BOND TO THE EQUIPMENT GROUND BUSS REMEMBER there may be a screw into the frame to accomplish that
THE THEORY FOR THE ABOVE and why I think Im still right regardless of being NEC stale is.
1) THE EQUIPMENT GROUNDING CONDUCTORS ARE SUPPOSED TO ONLYYYYYYYYYYY CARRY FAULT CURRENT (via a dedicated low resistance fault current return path) so the breaker will trip fast and deenergize maybe a hot case you might touch.
IT CAN SAVE YOUR LIFE 2) The (insulated so you dont touch it) Neutral GrounDED Conductor is for ONLY carrying normal return current NOT fault current. 3) If you mix n match and substitute one for the other and the right set of wrong things (opens, shorts etc) happen an appliances outer metal case you touch becomes the same as the insulated (NOT supposed to touch) Neutral and your body could be in paralell with a live current carrier I DONT LIKE THE SOUND OF THAT DO YOU?????????????
EQUIPMENT GROUND IS NOTTTTTTTTT NEUTRAL EQUIPMENT GROUND IS NOT SAME AS EARTH GROUND THE NEUTRALS ARE EARTH GROUNDED FOR SURGE AND LIGHTNING PROTECTION (Why engineers and electricians call them GrounDED Conductors)
When you re bonded Neutral to Ground at your subs YOU HAVE NEUTRAL CURRENT FLOWING IN PARALELL WITH THE EQUIPMENT GROUND and are making them the same.....Thats very very WICKED and badddddddddddd lol
SHOCKING LIVESTOCK ISSUES
There are indeed NEC exceptions for ag buildings used to house livestock BUT IM NOT CURRENT ON ALL THAT but can tell you this.
When wires like hots and neutrals and grounds are ran close by, mutual magnetic inductive couling and the capacitor affect may well elevate voltge on the ground wire AT A VOLTAGE HIGHER THEN MOTHER EARTH at some location away from the panel, so when old bossys nose touches a metal waterer SHE FEELS A SHOCK. Therfore if theres a ground rod right at the waterer wired to the case/frame that brings the case voltage back down to the same as the waterer so no shock for old bossy......
HOWEVERRRRRRRRRRRRR those ground rods DO NOT and are NOT to be substituted for the required buildings electrical service GroundING Electrodes. Right at the buildings service entrance you need its own suitable GroundING Electrode DONT USE THE WATER GROUNDS FOR THAT
NOTE AND DISCLAIMER like I said Im rusty on the Ag livestock building exceptions but best I recall thats why they have an exception to the otherwise SINGLE POINT GROUNDING METHOD
If I had the exact answer to the ag shock problem you know Id tell you but I just dont have time today to read up on it sorry, but think the above theory is correct and why a ground rod at a waterer prevents shock and may be permitted even if it defeats otherwise single point grounding BUT I STILL KNOW THOSE ARE NOTTTTTTT FOR USE AS THE SERVICE GROUNDING ELECTRODE........
PS You mentioned a panel with ONLY ONE BUSS, those are intended ONLY for main service entrance use where Neutrals and Grounds all tie together NOT SUITABLE AS IS FOR A SUB. However if you can modify it so all the grounds (and case/frame) tie together and the Neutral Buss is insulated off the case/frame it can work.
WHAT TO DO????? See if you can isolate the Neutral Buss in the subs insulated off the case frames, but the case/frame still tie to Ground buss remember..........
WHEWWWWWWWWWWWWWWWWWWW youre working me JD but Im glad to help. You sure do help others here..
John T (NO warranty, dont take my word alone for this, Ive been wrong before lol, so if a professional can help out here let me know but please sight some NEC authority (NOT just Billy Bobs method) so I can read up on it)