Running 125amp sub panel 300ft

[Hobby_Man22]

Still on the fence about where to put my building. First of all how many 125amp sub panels can you connect to a 200 amp main panel? Then the second question is would it be cheaper to have the power company drop another line in? Or is 250-300ft too far? I thought they did this for free.

 

[Hobby_Man22]

I know 2 gauge thwn wire is rated at 130 amps. I don't know what gauge it would have to be for a 300ft run underground though.

 

[mrobins297aaa]

I think you can put as many 125 amp sub panels as you want, your still limited by the 200 amps of the main.
I have two 100 amp sub panels off of my 200 amp panel.

 

[mike93lx]

You want to use a voltage drop calculator to determine gauge required.

If you are considering running copper, I would strongly recommend rethinking that. Aluminum will be a fraction of the cost

 

[mrobins297aaa]

I'm about 170' to my barn from the main panel and I ran four 2/0 al for 100 amp panel in the barn.
In hind sight I think I could have went a little smaller on the wire gauge.

 

[Hobby_Man22]

I'm about 170' to my barn from the main panel and I ran four 2/0 al for 100 amp panel in the barn.
In hind sight I think I could have went a little smaller on the wire gauge.

Better to go overkill and do it once. For some reason electricians aren't always happy to come back out 6 months later to do the job again.

 

[Hobby_Man22]

I'm about 170' to my barn from the main panel and I ran four 2/0 al for 100 amp panel in the barn.
In hind sight I think I could have went a little smaller on the wire gauge.

Is it a big deal to run this length underground? I would think they would just use gas powered trencher and make quick work of it.

 

[mike93lx]

Is it a big deal to run this length underground? I would think they would just use gas powered trencher and make quick work of it.

Never lived somewhere with rocks in the soil, huh?

Nothing is easy about trenching 300' in places like New England.

 

[mike93lx]

Better to go overkill and do it once. For some reason electricians aren't always happy to come back out 6 months later to do the job again.

Are you trying to reply to my comment about aluminum wire?

 

[Hobby_Man22]

Are you trying to reply to my comment about aluminum wire?

huh? No.

 

[Hobby_Man22]

Never lived somewhere with rocks in the soil, huh?

Nothing is easy about trenching 300' in places like New England.

No rocks here. Just clay. Texas gumbo they call it.

 

[mrobins297aaa]

Is it a big deal to run this length underground? I would think they would just use gas powered trencher and make quick work of it.

it wasn't a big deal for me but I don't have rocky soil

 

[Bert_]

I can trench 300' in an hour, it's not a big deal. You can run secondary 2-300 ft without an issue. Might need to bump the wire up a size.

 

[tez929rr]

Still on the fence about where to put my building. First of all how many 125amp sub panels can you connect to a 200 amp main panel? Then the second question is would it be cheaper to have the power company drop another line in? Or is 250-300ft too far? I thought they did this for free.

Another line means another meter and monthly meter charge.

 

[Bluearmflames]

300’ assuming maximum panel utilization, puts you at 2/0 copper. That’s assuming you are drawing 125 amps at the panel…

 

[theoldwizard1]

First, why do you think you need 125A ? Most DIY garages/shed can do fine on a 60A feed. The size of the main breaker does not matter. Worst case if you exceed the 60A feed in the main panel you will have to walk 300' to reset it.

Many POCOs will not install a second drop and meter unless it is for commercial or farm/ranch use.

 

[MushCreek]

4/0 in aluminum. Just google 'wire size calculator' to work this stuff out.

 

[1jeepfan]

I live in Texas and the local power company was more than happy to add a meter for my shop. But it wasn’t free!

 

[safnd2021]

I ran 250 ot triplex for 200 amp service 300 ft out to my building no problems ata ll

 

[Rusty Wrench]

I'm about 170' to my barn from the main panel and I ran four 2/0 al for 100 amp panel in the barn.
In hind sight I think I could have went a little smaller on the wire gauge.

Similar. 200' 3/0 direct burial aluminum to a 100A panel.
Can run 6.5kW heater, 25A compressor, 25A BendPak + shop lighting simultaneous. No trips.

Edit: for 300' I might bump to next wire size. This' where you might want a sparky.

 

[mike93lx]

I ran 250 ot triplex for 200 amp service 300 ft out to my building no problems ata ll

Hopefully you added a ground wire, or did that work a long time ago

 

[Skooterj]

I looked into having my POCO drop a separate service at my garage. The will install it for free, but it has a minimum service fee of $35 a month. So if I never turned a light on, it would still cost me $420 a year. I had a electrician quote me out $1200 to run 100 Amp service out of my main panel in my basement to the garage, install a new box and wire it all. Return on investment less than 3 years. If I do it myself, I figure I can do it for less than $600...

 

[dcg9381]

Is it a big deal to run this length underground? I would think they would just use gas powered trencher and make quick work of it.

Depends on your soil. Here's what I used. It wasn't quick or cheap.

 

[Rusty Wrench]

That's a badass attachment.

My electrician used a ditchwitch for direct bury cable. I've learned since the irrigation installers around here use a vibrating/slicing attachment to pull pipe through soil without opening a trench. By request they will pull electric conduit. It wouldn't have worked for me because our local code requires 30" deep with the locating tape 12" above that. But maybe an option for you.

 

[AP514]

Hell if your going 300 ft go at least 90 AMPs..
IMO 60 amp is wasting your money. It leaves you Zero upgrade room...
Also I went Copper for the WIN ...(Oh here comes the comments on that..:0 )

 

[mike93lx]

Hell if your going 300 ft go at least 90 AMPs..
IMO 60 amp is wasting your money. It leaves you Zero upgrade room...
Also I went Copper for the WIN ...(Oh here comes the comments on that..:0 )

There is no win in running copper over aluminum, but it is your money to do with as you please

 

[Hobby_Man22]

I did say 125 amps didn't I? Says it in the title.......

 

[mike93lx]

I did say 125 amps didn't I? Says it in the title.......

Old wizard suggested 60a was enough. That's how that sidebar got started.

 

[Hobby_Man22]

How can he suggest anything? I didn't even say how big the building was or what i'm putting in it.

 

[The Cobbler]

have you done load calculations to see what your draw is going to be? until you have that, the rest is basically irrelevant

 

[Hobby_Man22]

Yes. 125amp will be sufficient for now and whatever dumb idea I come up with in the future.

 

[Bert_]

A 2/0 aluminum would be a nice size. At 100a load the voltage drop is pretty reasonable. It's pretty rare to load a feeder to 100% and if you do it's probably only for a few minutes.

Nice thing about 2/0 is it will fit the breakers without having to reduce it and it will fit in the panels better too.

If you plan to load it heavy you could use 4/0 but there will be more hassle.

 

[Hobby_Man22]

Im liking this idea. Just put the second building 300ft away put a vehicle lift inside it and just buy another air compressor for that building too. That was the reason for connecting the two buildings was to make it so all my tools stay in one building, but I guess it's not that big a deal to just have a second smaller toolbox another compressor etc.

 

[csp]

How can he suggest anything? I didn't even say how big the building was or what i'm putting in it.

What does the building size have to do with electrical amperage needs?

I'm not going to lie, given what I've seen in your other threads I'm not convinced you know what your electrical needs are even if you do know what you're putting in it.

 

[dcg9381]

How can he suggest anything? I didn't even say how big the building was or what i'm putting in it.

FYI: We're kinda asking you: "Whatcha gonna do with it, IE - what's in it"?
Everyone here is trying to give you good advice. If you don't want to disclose, and just say, "I need 125A" - I get it, but you *might* be missing advice where you can step up to 150A or step down to 90A for some very marginal money.

FYI, I have a 2400 sqft shop in Texas, same state as you. I "get by" with 90A pretty darn well. And that shop has 2 ACs, a refrigerator, and a hot tub. I have a 240V MIG welder, run a 1.5 HP pump for our home, and have multiple RV connections.

Clarification appreciated, if you're willing to provide it.

 

[mike93lx]

Sometimes people don't want to share details. If the guy is sure 125a is the right number, so be it. We aren't saving the world here

 

[brownbagg]

are you going be pulling 125 amps at one time

 

[Hobby_Man22]

Sometimes people don't want to share details. If the guy is sure 125a is the right number, so be it. We aren't saving the world here

I like to think I'm pretty straight forward with my questions. Yes I don't like to spill out all the details all the time. Might as well post my address and send some of you guys out there to look for yourself

 

[Hobby_Man22]

Some people don't want to just get by. Some people want to not have to worry about it. I think it's dumb to have to remember to turn the air compressor off because if it kicks on when I'm using the welder it's gonna be dark in the shop. Then you have a friend show up one day and you have to explain this to him and he reminds you you're a cheap sob. Personally something like an electrical panel that's gonna be usable for the next 50 years isn't something to be cheap on. Now if you want to buy heb branded dr pepper vs the real brand now we're talking. To each their own......

 

[frankd]

Some people don't want to just get by. Some people want to not have to worry about it. I think it's dumb to have to remember to turn the air compressor off because if it kicks on when I'm using the welder it's gonna be dark in the shop. Then you have a friend show up one day and you have to explain this to him and he reminds you you're a cheap sob. Personally something like an electrical panel that's gonna be usable for the next 50 years isn't something to be cheap on. Now if you want to buy heb branded dr pepper vs the real brand now we're talking. To each their own......

It's not the cost of the panel. It's the 300ft of wire that's gonna get you. I recently added a sub-panel to a separate storage building. Mine was only about 100ft from the house. I rented what I thought was a large enough trench digger from home depot but the soil is very hard and rocky so we had quite a bit of trouble digging the trench. It doesn't sound like you'll have that issue.
If the local electric company will run a separate meter to your garage, then I'd have them do that. If not, I'd go with aluminum wire over copper. I used 6 gauge aluminum xhhw-2. I felt like I only needed 50 amps but if you're looking for 125, you'll probably need to go with 2/0.
I paid just over $100 for the wire. If I had gone with copper, it would have been well over 3 times the price.