200 amp sub panel in detached garage

[sabercatt]

Just wanted to see what size wire I need to run to a sub panel in my detached garage. seems to need 4/0 4/0 4/0 2/0 aluminum but wanted 2nd opinion. layout is this:

400 amp service -> 2 200amp panels inside house -> 1 panel for house / 1 panel for feed to garage.

200 amp breaker in garage panel fed 175 feet (100 feet inside house and 75 feet underground to building) to detached garage 200 amp sub panel.

4 wire with grounds and neutrals bonded at main and separated at sub. 2 ground rods at sub.

this sound about right?

thanks

 

[wyliesdiesels]

First we need to know what your loads are.

Do you really need 200a?

Is this a one man shop?

And 4/0 AL is too small for 200a.

 

[Stuart in MN]

Also, mention what type of AL wire you are planning on using.

 

[ard]

250 mcm gives you 182 ft, 3% drop, 200A, in conduit.

3/0 copper gets you 205 feet

 

[sabercatt]

I currently don't need 200a but who knows what the future will bring and I already have 400 amp service with an unused 200 amp panel. I was lookin at 4/4/4/2 urd direct burial.

 

[bjcouche]

A 200A service to a shop is way overkill, so unless you just won the lottery, save a bunch of money on the wire and spend it on tools, beer, women, etc. A one or two man shop will be hard pressed to utilize 90-100A. I have a buddy that has an 70A feed to his shop. 2 men work in there every day and they have 2 knee mills, 2 lathes, 1 3hp air compressor, and a Haas CNC machining center. They run multiple pieces of equipment simultaneously without issues. So unless you are doing commercial welding, 90A will suit you fine. If you have a 300A panel on hand, you can certainly use it. You would feed it with a breaker and cable sized for 90A and then place a label on the main 200A breaker handle as "disconnect". I would also put a label on it indicating it is a 90A feed, and where it was fed from too but that's just me. Also URD cable, unless it's dual rated, cannot poke through to the inside of your building, even in conduit. URD is only useful outdoors by the power company and not allowed indoors.
Brian

 

[sabercatt]

I understand where your coming from, but it will eventually feed all the lighting around my pond, the fountain in the pond, the 15-20 overhead lights, fridge, freezer, a/c, welders, r/v outlet, etc. I think its a good selling point if I ever move as well. i'd rather spend a bit more up front than regret it later.

 

[sabercatt]

i was not aware that urd is not allowed indoors so that is good info. my other option is to have a second meter and come in from the pole by the building. unfortunately my current service entrance is on the wrong side of the house for this project.

 

[wyliesdiesels]

Have you done a load calc?

And many PoCos charge higher/commercial rates for additional meters on the same property.

Inwould check with your PoCo before committing to a second service.

 

[matt_i]

Supposing you had a 200A panel already setup do you think you can ever draw 100A continuous (on 240vac)? That would be like $3-4 per hour in electricity....

I would try to write down a hypothetical situation where you can draw 24kW first.

I disagree about the potential selling point of a 200A feed to a shop unless its a commercial shop. Imo 100A is going to be past the 99% customer's needs.

 

[ard]

i was not aware that urd is not allowed indoors so that is good info. my other option is to have a second meter and come in from the pole by the building. unfortunately my current service entrance is on the wrong side of the house for this project.

Wait, because you can't run URD inside you are now talking about a second service?!?!?

Settle down, man.



Run PVC conduit, THHN, done.

(Other solutions include one cable on the interior, then to a junction box on the outside, then depart that box with URD into the ground.)

Also, you need 'something' to connect that 'second 200A panel' to the wire you are running. AKA 'a breaker'. Can you buy a 200A breaker for your 200A panel? Find out.


I am not one to argue people down from overkill- you want it, fine. Just dont be stupid about it..... Like put in 250mcm AL, then find out the largest breaker for the panel is ...less. Dunno, just thinking out loud...


What is the brand and number of your 200A panel? Lets go from there.

 

[Bib Overalls]

I have 70 amps in my shop. I keep thinking it is not enough and planned to upgrade when I added a 3.5 ton heat pump. My A/C guy said don't bother unless the lights momentarily dim when the unit powers up. Has not happened yet.

 

[sabercatt]

square d. already have an extra 200 amp breaker left from another project that will work. that project i pulled 160 amp continuous for 5 months straight and i may do a partial bit of that again in addition to my other more normal loads. just my welder alone will pull 60+ amps when welding thick aluminum.

 

[wyliesdiesels]

Wait, because you can't bury URD you are now talking about a second service?!?!?.....

Straight rated URD can be buried.

However, It CANT go inside buildings...

 

[ard]

URD can be buried.

It CANT go inside walls...

Fixed.

Cant go in the crawl space either I think...

 

[wyliesdiesels]

Fixed.

Cant go in the crawl space either I think...

yeah i shouldve said cant go inside buildings....

 

[Matt Matt]

Supposing you had a 200A panel already setup do you think you can ever draw 100A continuous (on 240vac)? That would be like $3-4 per hour in electricity....

I would try to write down a hypothetical situation where you can draw 24kW first.

I disagree about the potential selling point of a 200A feed to a shop unless its a commercial shop. Imo 100A is going to be past the 99% customer's needs.

I pretty much agree 100%!
But... if there is a 300 amp welder, an air compressor (which kicks in when ever it needs to) air-conditioning or Electric heating and one other large load, I would pull a 200 feed.

But, I personally find it a bit overkill too, without a load calculation.

I do have running to my garage/shop a bit more than 100 A(but, I have four feed lines from the main panel, 1 60 amp sub panel, 1 stove outlet, 1 15A split for 4 outlets and 1 15 single for lighting). But, I actually have a manufacturing facility out of my garage/shop, and I am a one-man shop.

 

[ard]

square d. already have an extra 200 amp breaker left from another project that will work. that project i pulled 160 amp continuous for 5 months straight and i may do a partial bit of that again in addition to my other more normal loads. just my welder alone will pull 60+ amps when welding thick aluminum.

OK

Is it a 'crawl space then out and into the ground' situation?? Personally I'm a conduit fan- especially the underground bits.

Go for it. 250kcmil aluminum. Or 4/0 CU. I think the AL will be at 50% with 2" PVC.

Or bury the URD, and mount a junction box on the exterior wall to splice. Run the URD in conduit until below grade. In the house, use a cable rated for inside- I think SEU?

 

[Matt Matt]

OK

Is it a 'crawl space then out and into the ground' situation?? Personally I'm a conduit fan- especially the underground bits.

Go for it. 250kcmil aluminum. Or 4/0 CU. I think the AL will be at 50% with 2" PVC.

Or bury the URD, and mount a junction box on the exterior wall to splice. Run the URD in conduit until below grade. In the house, use a cable rated for inside- I think SEU?

Yep! .

 

[wyliesdiesels]

OK

Is it a 'crawl space then out and into the ground' situation?? Personally I'm a conduit fan- especially the underground bits.

Go for it. 250kcmil aluminum. Or 4/0 CU. I think the AL will be at 50% with 2" PVC.

Or bury the URD, and mount a junction box on the exterior wall to splice. Run the URD in conduit until below grade. In the house, use a cable rated for inside- I think SEU?

SER not SEU

 

[pattenp]

I'm not getting into whether you need 200A or not, but if it was me, I'd use 4/0-4/0-4/0-2/0 Mobile Home Feeder (MHF). The MHF can be run inside the building in conduit and be direct buried where outside. The 4/0 Al is rated at 180A per the NEC when used as a branch feeder, but seeing there is not a 180A breaker made you can go to the next standard size which is 200A. The bottom line is if this is being inspected your inspector may not allow the 200A breaker on 4/0 Al and make you use a 175A breaker. If that's the case then 250 kcmil size is needed for 200A and you'll need to find individual wires of aluminum RHH/RHW-2/USE-2 rating that can enter the building and also be direct buried if not running conduit the whole way. If doing conduit the whole run then use aluminum XHHW-2.

Examples of wire:
https://www.wireandcableyourway.com/XLP-USE-2-RHH-RHW-2-Aluminum/
https://www.wireandcableyourway.com/XHHW-2/
https://www.wireandcableyourway.com/Mobile-Home-Feeder/

 

[ard]

This is OT, but what size wire do you think his POCO used for his "400 Amp" service?

250? 350?

Would be interesting to see....

 

[Norcal]

This is OT, but what size wire do you think his POCO used for his "400 Amp" service?

250? 350?

Would be interesting to see....

Does not really matter as they are under different rules then we are.

 

[zmotorsports]

Supposing you had a 200A panel already setup do you think you can ever draw 100A continuous (on 240vac)? That would be like $3-4 per hour in electricity....

I would try to write down a hypothetical situation where you can draw 24kW first.

I disagree about the potential selling point of a 200A feed to a shop unless its a commercial shop. Imo 100A is going to be past the 99% customer's needs.

Not trying to deter you from running a 200-amp service because that is what I ran out to my detached shop and it is just my son and I in the shop working 90% of the time. The other 10% it is only one of us.

That being said, I know it is overkill and definitely cost me more to run than a 100-amp service but luckily my shop is only about 50 feet behind the house.

As to the comment about it adding to the resale, I highly doubt it. When I sold my last home and shop of all the people that came to look at it and most people wanted the shop as the house was just a modest smaller home, no one even asked about how much power I had run out there. Those that I could tell were interested when looking at outlets both 110volt and 240 volt I explained I had a 125-amp service ran to the shop and I could tell they didn't have a clue but were excited to see the welder outlets and all of the 110volt outlets. It wouldn't have mattered whether I had a 100-amp or a 400-amp service on resale. Detached garages are a poor investment anyways as you only get pennies on the dollar when selling.

Mike

 

[bjcouche]

If you really think you want that 200A service, then do two things first. Do a load calculation, both on your shop (and stuff fed from your shop) and your house. Next contact your power company to figure out what the costs are for adding a _second_ service to your property for your shop. As others have said, some power companies simply won't do it, others will do it but charge you big bucks for it and then charge you commercial rates or minimum monthly service charges. Other power companies will give you a second service without any fuss. Either way though, if you get a second service, it's very likely the second service is just going to be tapped onto your existing transformer... If the poco is going to add a second transformer then you'll know it by the line item in the bill when they charge YOU for the transformer.
Brian

 

[Markfothebeast]

Our old home had a 60 amp lug fuse main just last year and we replaced everything from the top of the pole down. Ran 100a to house and 100a to garage.

I'll most likely never exceed 100a in the garage even if I turned on all my tools, lights, and air compressor at once.

The neighbors somehow manage to operate on 60a or 100a service running a large buzz box AC welder, 60a hot tub, appliances, central air, a barn and 2 houses.

Sent from my SM-G920V using Tapatalk

 

[sabercatt]

This is OT, but what size wire do you think his POCO used for his "400 Amp" service?

250? 350?

Would be interesting to see....

I think its 350, but I didn't measure it and it wasn't marked.