200 amps at 100 feet, residence - size and wire count

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wdg

Member
Location
Science Hill, KY Pulaski county
History
We are building a house with service from the road to a 400 amp meter can. The can has two 200 amp breakers, one to serve the shop and the second to serve the house so the shop and house breaker boxes are sub-panels.
I'm okay with the shop as that breaker box is on the other side of the wall of the meter can.
Our state/utility is still using 2014 NEC for code compliance.

My Questions
The 200 amp service from the breaker in the meter can to the house will run 100' underground.
1) Will 4/0 Alu support the house or do I need to step up to 250 kcmil?
2) Since this is a sub-panel, do I need to pull 4 conductors or can I set two ground rods at 6' at the house and delete the ground back to the meter can?
3) Can I do this in 2" PVC?

I appreciate in advance the help. In the work I do, electrical overlaps into it every day but I'm still learning my way around the NEC and in this case, don't want to dump a bunch of money and effort on wire too small.
I would appreciate code references in any response to help in my continued learning.
Again, thanks to all.
 
electrofelon

electrofelon

Senior Member
Location
Cherry Valley NY, Seattle, WA
wdg said:
History
We are building a house with service from the road to a 400 amp meter can. The can has two 200 amp breakers, one to serve the shop and the second to serve the house so the shop and house breaker boxes are sub-panels.
I'm okay with the shop as that breaker box is on the other side of the wall of the meter can.
Our state/utility is still using 2014 NEC for code compliance.

My Questions
The 200 amp service from the breaker in the meter can to the house will run 100' underground.
1) Will 4/0 Alu support the house or do I need to step up to 250 kcmil?
2) Since this is a sub-panel, do I need to pull 4 conductors or can I set two ground rods at 6' at the house and delete the ground back to the meter can?
3) Can I do this in 2" PVC?

I appreciate in advance the help. In the work I do, electrical overlaps into it every day but I'm still learning my way around the NEC and in this case, don't want to dump a bunch of money and effort on wire too small.
I would appreciate code references in any response to help in my continued learning.
Again, thanks to all.
Click to expand...

Its very unlikely you will need to upsize the wire for that length for a residence. Yes you will need 4 wires as the NEC removed the exception for rebonding the neutral for remote structures. I would pull 4/0, 4/0, 2/0, #4 Al (maybe #6 CU for the EGC, but remember it has to be green). 2" should be fine.
 
kwired

kwired

Electron manager
Location
NE Nebraska
Voltage drop is dependent on amount of current and conductor size/type. Just because you have a 200 amp overcurrent device on the supply to the dwelling doesn't mean it draws 200 amps. Many never come all that close to drawing 200 amps, which means the amount of voltage drop you see is less then it would be if it were drawing 200 amps.

Other factors to consider though is how much of a surge in current is there when say the AC compressor starts, and how far and what size conductors are there between the meter and the source. Starting of that compressor may give enough drop to cause an annoying flicker in lighting though it only lasts a second or so and then voltage is acceptable again. 100 feet on a 200 amp dwelling service is usually not a concern for voltage drop, unless the load calculation is toward the upper end of 200, but if it were another 100 feet from the meter to the source you might want to look harder at just what you have there as it is starting to get long enough to raise concerns.
 
R

ramsy

Roger Ruhle dba NoFixNoPay
Location
LA basin, CA
Occupation
Service Electrician 2020 NEC
wdg said:
History We are building a house with service from the road to a 400 amp meter can. The can has two 200 amp breakers, one to serve the shop and the second to serve the house so the shop and house breaker boxes are sub-panels...
Click to expand...
Why can't PoCo's service drop hit riser at 1st structure?
100ft+ drops are not unusual, if available. Cost may equal Zero.
 
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