Hi,

My name is Jeff, I am over 50 from the construction trade. 3 years ago I wired a lock off basement of some 1600sf w/ bdrm, kitchen, bath, theatre room, lots of lighting and more (all 120v circuits). I passed all inspections with no problems and even a few cudos from the inspector. So I have some experience.

I am in the planning stages for rewiring some out buildings on a property I recently purchased. I am having trouble understanding voltage drops and I really want to do this right. So here goes. From the main panel to the nearest corner to out buildings is 100’. Currently at that corner there is a 3wire #6 from the main panel to a fused disconnect to run a well pump, in ¾” emt for the metal ground. From that corner to the middle out building is approx. 130’ and then 40’ to each bldg from there. Each out building is approx. 22’ by 100’ greenhouse, with approx. 8’ between for a total of 270’ to farthest building from main panel. Metal frame with thick plastic (pvc) type covering, plywood ends w/ garage doors. In each building will be a propane space heater 2.8amp motor, 1500 watts of lighting, 2 receptacles for occasional power tools or fans or whatever (1-20amp circuit and 2-15amp circuits).

Here is my plan (all copper):
Replace well circuit w/ 3wire #2 + grnd, to Sub panel #1 off 100amp breaker @ main panel (100’ run). This panel will run the well and 2-20amp receptacle circuits for now. Go from this panel to Sub panel #2 w/ 3wire #2 + grnd off 100amp breaker @ Sub panel #1 (130’ run). This panel will feed the 3 out bldgs described above by placing 4circuit Sub panels #3 and #4 in the other bldgs. Both runs are 40’ of 3wire #6 +grnd. I was planning a grnd rod at panel #1 and #2, do I need them at #3 and #4 as well? Also is the fused disconnect for the well still required if the breaker will be right next to the motor controls?

My calculation is that I can run 32-40 amps out of Sub panel #2 with this Plan. The actual would probably never be more than 20-23amp draw at any given time.

Does this seem OK and to code before I pull permits, and I don’t know yet what size the grnd wires should be. I welcome your input please.

Generally your plan sounds fine.let me see if I can address your questions.

The equipment ground for the 100 Amp feeder needs to be min # 8 copper.

Yes, ground rods are needed for each panel in each separate building.

A fused disconnect for the pump is not needed to protect the pump circuit you can rely on the circuit breaker in the panel. A service disconnect, nonfused, may be needed at the pump location to service the pump and have a switch in site of the motor. If the fused disconnect acts as the service switch, then fine, leave it.

TK,
Thank you for your response, I appreciate the input very much.