Upcoming wire pull and conduit calcs

J

Jeronimo

Member
Location
NorCal
Occupation
Wireman
Hello everybody. Long time lurker

I've had to leave my former union employment and strike out on my own which is exciting... I'll be getting my contractors license soon. I have the money set aside and I have to complete one larger job before I can take time off and get it all done.

I have some trepidation about my calculations and would like to hear anybody else's raw input:

200A split phase resi service
345' underground from owner-owned pole im installing to utility spec.

Customer like the price of aluminum:

Using the 2020 nec

2" pvc sch 40
2x 350kcMil phase
1x 3/0

Calculated voltage drop

2-k-I-L
---------
Cm|Vd

My math works (tight tolerances on the 40% conduit fill)

But I just downloaded southwire's app and it's giving me waaaay different numbers

Can you tell me what you get?
 
Jeronimo said:
Hello everybody. Long time lurker

I've had to leave my former union employment and strike out on my own which is exciting... I'll be getting my contractors license soon. I have the money set aside and I have to complete one larger job before I can take time off and get it all done.

I have some trepidation about my calculations and would like to hear anybody else's raw input:

200A split phase resi service
345' underground from owner-owned pole im installing to utility spec.

Customer like the price of aluminum:

Using the 2020 nec

2" pvc sch 40
2x 350kcMil phase
1x 3/0

Calculated voltage drop

2-k-I-L
---------
Cm|Vd

My math works (tight tolerances on the 40% conduit fill)

But I just downloaded southwire's app and it's giving me waaaay different numbers

Can you tell me what you get?
Click to expand...
It will depend on what value you use for the current. Using the full 200 amps is unrealistic and would be waste. I would probably use something around 80 to 100 amps for a run of the mill house, depending on various things.

Be careful with that wire combination, there is a moderate risk of jamming if it is not plexed. I know it's a big price jump but you might want to consider going up to two and a half inch conduit or ordering in Plexed conductors. Unfortunately 350 urd is a hair over 40% fill
 
I'm with Electrofan, I would not likely increase my wire size that much for voltage drop, unless the panel is that loaded. Perhaps us 300 Aluminum
 
I agree with electrofelon and would change one of two things. Either smaller conductors or a larger raceway.
 
agree with rob and electrfelon. I didn't do any calculations but did you take into account you might need to be using Sch 80 where your PVC is exposed.
 
Larger pipe would give a better pull even with a tugger. Also account for the sched 80 on exposed up the pole.
Question your POCO is allowing you to go from your private pole to underground without having meter and disconnect at the pole?

You might need to calculate for 4 wire after that first disconnect. Around here POCO wouldn't allow it without the meter and disconnect at the pole when transition from the the POCO wire to the Private underground.
 
Fred B said:
Larger pipe would give a better pull even with a tugger. Also account for the sched 80 on exposed up the pole.
Question your POCO is allowing you to go from your private pole to underground without having meter and disconnect at the pole?

You might need to calculate for 4 wire after that first disconnect. Around here POCO wouldn't allow it without the meter and disconnect at the pole when transition from the the POCO wire to the Private underground.
Click to expand...
There will be a meter main at the pole

250.142 for 3-wire setup
 
Strathead said:
I'm with Electrofan, I would not likely increase my wire size that much for voltage drop, unless the panel is that loaded. Perhaps us 300 Aluminum
Click to expand...
Its a "hobby winery. And 3 story vacation home. 2x level 2 car chargers, tesla wall, and 200A SPAN panel

I think I'm ok going with the larger conductors
 
electrofelon said:
That's will be much easier. Have you looked into going with 350 URD("wesleyan").? Might even be cheaper than single conductors. It will have a 4/0 neutral.
Click to expand...
i gave him the option - it's very limiting in terms of serviceability/replacement but yeah he'll save about $1300 in conduit alone
 
Jeronimo said:
There will be a meter main at the pole

250.142 for 3-wire setup
Click to expand...
But your underground will be on load side with a meter/main at the pole, so you can't use 250.142(A) Supply Side Equipment for 3 wire. So you have to use:
250.142(B) Load-Side Equipment.
Except as permitted in 250.30(A)(1), 250.32(B)(1), Exception No. 1, and Part X of Article 250, a grounded (Neutral) circuit conductor shall not be connected to non–current-carrying metal parts of equipment on the load side of the service disconnecting means or on the load side of a separately derived system disconnecting means or the overcurrent devices for a separately derived system not having a main disconnecting means. NFPA 2020

So with 120/240 single phase you would have 2 hot a neutral and a separate grounding conductor from the meter/disconnect to the panel in the dwelling. Also a Grounding Electrode System at the pole structure and at the dwelling.
 
You must log in or register to reply here.
Top