[lil_TXRanch]

Ok, so here's my situation.

I am having a 30' x 50' x 12' workshop erected on the property I own and I need to get power to it.

I have determined that I will need 150 amp sub-panel out at the shop, which includes my anticipated future loads:

• Three 240 volt loads (50 amp compressor, 40 amp welder, 40 amp A/C unit)
• Three 20 amp loads (Five 8' Florescent lights per breaker)
• One 15 amp breaker for lighting over workbench area
• One 15 amp breaker for outside lighting/receptacles
• Five 20 amp breakers for branch circuits (4 receptacles per breaker)

Does this sound like an appropriate load calc??

The problem:

The shop is ~400 feet from the meter pole. The way the electrical is set-up is that my meter loop is 200A which feeds the 200A panel inside our home.

What I think I need to do is upgrade the meter loop to a 300A panel, then run a 200A breaker to the house and a 150A breaker to the shop, does this sound reasonable or correct?

I believe, based on my rough voltage drop calc, I'm going to have to use 3/0 wire from the meter to the shop (~400 ft), does this sound correct?

I would run 3 3/0 wires through 2.5" conduit, not sure on the size ground; only two 90 degree turns in conduit.

I'm also going to have the concrete guy lay in grounding wire into the slab to connect to the shop sub.

This is kind of where I'm at, as pricing out the electrical stuff is the last step I need to price out. I'm confident that I can get the work done and the only thing I may hire out to an elctrician is to upgrade the box at the meter.

Thanks ahead of time for you input, questions, corrections, and so forth.

-Patrick

P.S. Having the utility come out and drop another meter by the shop is cost-prohibitive due to the monthly service charge, regardless of power used or not.

[tkrussell]

Yes you can have a 320 amp service meter with two disconnect built in, a 200 amp and a 150 amp.

150 Amp equipment is an odd size, you can get a meter with two 200 amp breakers built into a 320 amp meter.

If you plan to use PVC conduit, then the two 90 Deg sweeps should be steel rigid conduit, as the PVC sweeps will be damaged by the friction of pulling the conductors that distance. I would try to incorporate handholds at each end of the pull to eliminate having to pull that distance of wire through sweeps.

The feeder will need an equipment ground in addition to the 2 hots and one neutral, size to be determined. Since the feeder will need to be oversized to reduce voltage drop, the equipment ground will need to be increased proportionally.

Now onto the voltage drop. Assuming the #3/0 you mention is copper, the max distance that #3/0 copper can deliver 150 amps at 240 volts and keep the voltage drop to 3% is 273 feet. So that does not sound like the correct wire size.

There is no "rough calculations" when calculating voltage drop.

Exactly how did you come up with #3/0?

And is it copper or aluminum?

How much of the load will run at the same time?

What is the exact load of each unit in amps?

If the feeder is not sized properly, you will have problems starting the air compressor motor, the AC, etc. and can do damage to these units.

The most important value needed to do voltage drop calcs is the load amps.

[lil_TXRanch]

Yes you can have a 320 amp service meter with two disconnect built in, a 200 amp and a 150 amp.

150 Amp equipment is an odd size, you can get a meter with two 200 amp breakers built into a 320 amp meter.

Excellent, that's kind of what I figured.

If you plan to use PVC conduit, then the two 90 Deg sweeps should be steel rigid conduit, as the PVC sweeps will be damaged by the friction of pulling the conductors that distance. I would try to incorporate handholds at each end of the pull to eliminate having to pull that distance of wire thru sweeps.

Perfect. So would the 2.5" PVC I mentioned be the appropriate size?

I assume there's a special fitting that is best to link the PVC with steel??

Hand holds?

The feeder will need an equipment ground in addition to the 2 hots and one neutral, size to be determined. Since the feeder will need to be oversized to reduce voltage drop, the equipment ground will need to be increased proportionally.

What size ground do you calculate as appropriate?

Now onto the voltage drop. Assuming the #3/0 you mention is copper, the max distance that #3/0 copper can deliver 150 amps at 240 volts and keep the voltage drop to 3% is 273 feet. So that does not sound like the correct wire size.

There is no "rough calculations" when calculating voltage drop.

Exactly how did you come up with #3/0?

And is it copper or aluminum?

By "Rough" I meant I searched online for a voltage drop calcualation, plugged in some figures I had and came up with 2.96% drop. It's rough because I went into it knowing that it wouldn't be that easy.

Would 4/0 work, something bigger? Is there another, cost-effective, alternative to running power that distance without using the utility?

How much of the load will run at the same time?

What is the exact load of each unit in amps?

The only things I could imagine running continuosly would be the lighting circuits and A/C, figure greater then 3 hours, so 125% of the load, would give you a combined amperage of 144.

I figure during that time you would also see some of the branch circuits used, with the compressor being the only other large load that would kick in for a short amount of time.

If the feeder is not sized properly, you will have problems starting the air compressor motor, the AC, etc. and can do damage to these units.

The most important value needed to do voltage drop calcs is the load amps.

Agreed which is one of the reasons I'm seeking help, know very little about voltage drop and sizing of SE wiring.

[lil_TXRanch]

And as always, thanks for all your help!