How much power?

[BrianS]

This spring I will be building a new home complete with a detached garage for my toys. I'm debating the amount of power I will need both in the house and in the garage.

Currently I have 200 amp service spec'd for the house with a 100 amp sub-panel in the detached garage.

I was quoted about $1500 to take that to 400 amp house service with 200 amps at the garage.

I currently don't have any power hungry devices but I may in the future. I was considering putting the PEX in the slab for future radiant heat and since we don't have natural gas I would need an electric boiler. My research seems to show those things need tons of power, like 3x40amp breakers.

Also may have a compressor and other power tools out there.

Is 100 amps going to be enough?

 

[t. jones]

Is the house electric heat? You probably need more power in garage than house. That said I get by with 100 amp house feeding 40 amps to garage, just can't run 2 machines at once. I have gas heat in both. Thanx Trevor

 

[Norcal]

This spring I will be building a new home complete with a detached garage for my toys. I'm debating the amount of power I will need both in the house and in the garage.

Currently I have 200 amp service spec'd for the house with a 100 amp sub-panel in the detached garage.

I was quoted about $1500 to take that to 400 amp house service with 200 amps at the garage.

I currently don't have any power hungry devices but I may in the future. I was considering putting the PEX in the slab for future radiant heat and since we don't have natural gas I would need an electric boiler. My research seems to show those things need tons of power, like 3x40amp breakers.

Also may have a compressor and other power tools out there.

Is 100 amps going to be enough?

There is only one way to know your needs, you need a load calculation.

 

[malibu101]

Excuse me for not commenting on many of the things you're asking about.
But, let me comment on the electric boiler. If you go with one of any reasonable size you will want/need more than 100A single phase to satisfy it and and the other stuff that may be used at the same time.

 

[rodnok1]

My locals wanted to know why I put 200 amps to both house and pole barn(storage don't ya know, I said well hell I do want to run an air compressor, weld and maybe put a heater in it to be able to fix a tractor in the winter and it's 350 feet from the splitter box. Put the 200 amp into both if you can afford it, what if you want to put a Rv and a hot tub inot the barn?

 

[rburke65]

Need a load calculation like norcal said. If you are going to have electric heat, then I'd be leaning to the 400 amp in the house and 200 to the garage, then you would be in Fat City with no need to worry!

 

[JBurgess]

I have never met anyone who said "I wish I had put in a smaller electric service". I have however met many who wish they had put in a bigger service the first time.

Having a bigger service can other benifits besides more power available, the utility usally runs bigger wires to the house and sometimes puts in bigger transformers. This helps prevent things like the lights dimming in the house when your compressor starts.

If your utility does not charge more per month for the 400 amp service, you should strongly consider it.

 

[Ezzie]

I did it the other way around. 100A to the house, 200A to the shop (but I have natural gas to use for heat, hot water and stove. The only significant load in the house is an electric clothes dryer.

 

[Iroc-Z]

You guys are sure talking about allot of power. Do you realize how much power 200 amps is? I put a two 100 amp sub panels off my 150 amp main panel in my house. One right next to the original panel and the other is in my garage. I talked to my electrician about upgrading to a 200 amp house panel and he asked why. He said if your pull 150 amps of power though your house that would be like a 600-700 dollar a month electric bill. He said most houses use 200 amp panels because they are cheap and readily available. Just my .02 cents.

 

[BrianS]

The house will probably be geothermal which obviously requires less power than electric heat. I'll also have propane available, but no natural gas.

I guess the heat for the detached building is what I need to decide on. Initially it won't be heated but I plan to add it in the future, just not sure how I plan to do it.

 

[NUTTSGT]

I have a 200 amp in the house and a second 200 amp in the garage, on separate services. The garage electric bill generally runs me 25-30 bucks a month, including using a welder and 220V compressor.


I also am in Ohio and have AEP.

 

[W_A_Watson_II]

I have 400 amps to the Shop and 400 amps to the House. However I started out as a single 400 amp feed, 200 each, but the electrical run to he shop from the house would have been over 300 feet and the quick cost solution was to run a separate feed, so I went for 400 amps, the 400 at the house is overkill now.

 

[AZ Garage]

The only time I've seen homes with 400A of power required many A/C units and were over 3K sq. ft..

 

[tdkkart]

A prime reason for a 200 amp service is to have a large enough breaker box to get all the breakers you need for a reasonably well layed out and electrically seperated shop.
By the time you put in 1 or 2 welder outlets, a couple compressor outlets, a couple breakers for you heating system, maybe a couple 220v breakers for machine tools or woodworking tools etc, you've got a pretty full 200amp box and you haven't even done lighting and standard 110v receptacles yet.
My shop is only 30x40 and I have the majority of a 200amp box full, might have 8 slots left, and I may end up with another 220v circuit for my heat, and another for a 3phase rotary converter sometime in the future.

 

[W-Cummins]

I have never met anyone who said "I wish I had put in a smaller electric service". I have however met many who wish they had put in a bigger service the first time.

Well I did and I'm glad I did. I re-rated my main breaker and installed a smaller service.

Having a bigger service can other benifits besides more power available, the utility usally runs bigger wires to the house and sometimes puts in bigger transformers. This helps prevent things like the lights dimming in the house when your compressor starts.

Well they might run new wire to your feed if they think it's needed, but they will almost never change the transformer. Transformers cost money to run, and unless they know your going to be pulling the amps they will not just change it. The power co knows that the 98% of home owners that think there home is in need of 400 amp will NEVER pull any where near that much power. In the neighbor hood I used to live in had 5, that's ~5~ houses on one 12kva can. Yes they were older smaller homes but they had 100 amp services. So the power co thought they could feed 500 amps of "potential" amp load with one 12kva transformer. The power co also gets away with using wire that would make the NEC cry to feed your house. On my service the power co has 25kva cans for the main transformers, but I have to have (NEC) a 75kva transformer just to feed my subpanel.

William....

 

[PassnThru]

Put the 200 amp into both if you can afford it, what if you want to put a Rv and a hot tub inot the barn?

We will be invited to the party, right??