Apprentice Looking For Some Insight

[crispysonofa]

Hello! what a great community this is and a wealth of knowledge! I have been working in the trade for almost 3 years doing mainly residential work. I have done plenty of service installs but haven't designed any myself as far as conductor sizing/load calculations. I am looking for some insight and making sure I am doing everything correctly. I want to get comfortable designing my own systems as I get closer to becoming licensed. I think the best way for me to learn is use real world scenarios. So today I started to try and design a 200 Amp 240v single phase 3 wire service for a barn that is not a dwelling. It exists 100 feet from the pole. I want to list what I think I could use and then you guys can tell me I'm wrong I am a little confused as to how I would do a load calculation for a barn. Would I use the dwelling calculation of 4VA/SquareFoot for lighting and general receptacle loads? I think I can use 2inch PVC with 3, 4/0 Alum USE conductors, my voltage drop would be 2.3% at 100 feet. I would use #4 bare for my ground rods. I understand that 2 inch is the minimum size and would most likely oversize them a bit (2.5 or 3). Also I'm not sure if Arc faults would be required in a barn or if I would use GFI protected circuits? I have my 2017 codebook handy I'm just trying to learn as much as I can. I really appreciate the insight!

 

[Coppersmith]

I started to try and design a 200 Amp 240v single phase 3 wire service for a barn that is not a dwelling. I am a little confused as to how I would do a load calculation for a barn.

If you have already decided it's a 200 amp service, you don't need a load calc. The purpose of the load calc is to decide the service size.

 

[Coppersmith]

It exists 100 feet from the pole. my voltage drop would be 2.3% at 100 feet.

If the pole you refer to is the utility owned pole, you don't need to calculate voltage drop from there. It's up to the utility to provide you the proper voltage at the "service point" (check definitions in your code book). They will provide the service drop from the pole to your mast. (Assuming they will go 100 feet, my POCO does a max of 100 feet.) You begin measuring voltage drop from the service point. For underground service, it's still their responsibility and they install the conduit from the pole unless you make a deal with them.

P.S. They usually use direct burial cable, so no conduit.

 

[crispysonofa]

Wow that was fast! Sorry I should have been more specific. Where I am from the meter usually goes on the structure that is getting the service and the customer is responsible for the underground service to the pole. We install and wire the meter socket which is why I calculated the voltage drop from the meter to the street. I heard my boss on the phone the other day with the POCO and they asked him for load sheets which is what got me thinking that I should know how to calculate the load. I understand that this data is required to determine the service size but I didn't see barns specified in the code and wasn't sure if I would use the dwelling calculation to be on the safe side? I really appreciate the input!