Quick - Electrician needs to know how many amps I require!!!

So, SWMBO and I are building a house, like, in the next week or so we will be breaking ground. In an attempt at foresight, I asked for a "220" circuit for the garage months and months back when we were still planning. I have no welder, or lift, or 3 phase tooling or anything of the sort, but am hoping to at least add a decent size 1ph lathe, maybe a big compressor, and a model-yet-undecided-upon welder to the arsenal. The electrician bidding on the job has asked the contractor what amperage to build the circuit to, which the GC then passed on to me. I have no idea, I never have even laid my first weld yet, so it will all be new to me, but I always hear guys saying "Wish I had thought to add 220 when I built the garage" right before taking another sip of their beer and going back to staring aimlessly at the project car.

So, whats the right answer? I dont foresee myself trying to get a flux capacitor up and running, but a big compressor or a welder or both are definitely on the table. I dont know what a typical amperage:$ ratio looks like, but money is definitely an object in this build - I need the cost to stay reasonable, so no "able to jump start a battleship" ideas. HALP!!!!

Tell him to put a 30 amp 6 breaker sub panel in the garage. That way you can run a couple circuits from it later in plastic conduit. If you plan to have a large concurrent load - like your powder coating oven is baking while you run the lift and TIG weld aluminum... make it 50 amp.

The plug on most new 220v stick welders is 50A, I would build to that. In electrician speak you want a stove (50A) vice dryer (30A) for the wiring. Plan big and even an electric car charger would be fine. I would second the sub panel too, as well as additional lighting.

I'm not an electrician but I have a couple things for you to think about. is the garage attached or separate? if the garage is attached you could consider running a separate conduit for 220 and have the wires pulled later when you need it , and concentrate on having room to grow on the house service side. if the garage is not attached, you want to make sure the conduit is large enough to pull some heavy gauge wire later on. how many amp service do you have running to the home? I think 200-400 amp is pretty typical for a 3 or 4 bedroom house. I doubt you will ever need to use multiple 220 tools at the same time so do a little research and see what the max amps you think you'll need for the welder plus lighting plus some head room for your tunes and whatever else you might need running. if you set up a 400 amp box in the house and then a 100-200 amps to the garage you would be in pretty good shape with some overhead. it really depends on the size of the garage, house, and the lighting requirements. the biggest draw will be for the welder and the lights simultaneously. another thing to think about is for small gauge steel you really don't need a ton of power for your welder. plenty of people do fine with 120v set up but I agree, if you are building a home, over build the electrical

I have a 100 amp main panel in the house and a 60 amp panel in the garage.

If this is going to be a working garage, then I would recommend you do the same. #phase does not enter into the equation since it is generally not available to a residence.

100 amp. You will use it, you know you will

TRoglodyte wrote: 100 amp. You will use it, you know you will

This.

Welder, A/C, 5hp air compressor, if they all are running at once the amps add up quickly.

in this case,, bigger is always better

Thanks guys, I think I'm gonna go with a mix of the ideas here -70amp on a sub panel...hopefully will provide plenty of punch and expandability without adding too much $$$

4cylndrfury wrote: Thanks guys, I think I'm gonna go with a mix of the ideas here -70amp on a sub panel...hopefully will provide plenty of punch and expandability without adding too much $$$

I'd do a 100-150 amp sub panel. The cost at time of construction will be minimal and you can never have too much capacity. More is always better.

psreynol wrote: I'm not an electrician but I have a couple things for you to think about. is the garage attached or separate? if the garage is attached you could consider running a separate conduit for 220 and have the wires pulled later when you need it , and concentrate on having room to grow on the house service side. if the garage is not attached, you want to make sure the conduit is large enough to pull some heavy gauge wire later on. how many amp service do you have running to the home? I think 200-400 amp is pretty typical for a 3 or 4 bedroom house. I doubt you will ever need to use multiple 220 tools at the same time so do a little research and see what the max amps you think you'll need for the welder plus lighting plus some head room for your tunes and whatever else you might need running. if you set up a 400 amp box in the house and then a 100-200 amps to the garage you would be in pretty good shape with some overhead. it really depends on the size of the garage, house, and the lighting requirements. the biggest draw will be for the welder and the lights simultaneously. another thing to think about is for small gauge steel you really don't need a ton of power for your welder. plenty of people do fine with 120v set up but I agree, if you are building a home, over build the electrical

adding an empty conduit is a fantastic idea.

Go 90 amp sub panel. If its an attached garage and close enough to the main panel you will just have a main breaker less sub which is cheap. 90 amps is ideal because this let's you use 2ga aluminum which is cheap relative to the larger gauge aluminum or copper required for 100amp. 80amp breakers/panels seem to be more availabke but at a electrical supply place he should be able to get 90.

Might as well just go with 100 amp service. That way should you end up with 3ph machine tools, you can have plenty of power to run a converter alongside everything else (compressor, welder, etc.). Also spend the extra money and wire all the 110 circuits 20 amps(12 gauge), that will give much better performance with 110 volt welders and bigger 110 motors.

A 60 amp subpanel is going to be more than enough for most people, but since this is new construction a bigger subpanel won't add that much to the cost. Nocones mentioned 90 amps - this is actually a common thing due to how the NEC is written; #2 aluminum wire is OK for 100 amps if you use it for an incoming service from the electric utility, but it's only good for 90 amps if it's used for a branch circuit from your main panel to a subpanel. What you use is a 100 amp subpanel with a 90 amp main breaker in it.

And, for the record: the standard voltages in the US these days are 120/240, not 110/220.

110, 111, whatever it takes.

I am an electrician. 200 amp single phase is common and plenty for your house. From the main panel run a 1" conduit to the garage and put in a 60 amp sub panel. The only reason I would consider increasing the amperage is if the furnace and water heater are not gas but electric. I once put a 400 amp service in a house but that was 6000 square feet and a 4 car garage. As far as 3 phase for residential, it is extremely rare. I have a 100 amp ( that I have not yet changed to 200), a 60 amp sub panel on my second floor and a 30 sub panel in my detached garage. My house is 2500 sq ft with a basement, 2 central air units a pool pump and 2 kids with every light in house on and I am fine.

I've got 200 amp service for the house and an 80 amp sub in the garage. Just finished the wiring in the garage. Get more outlets than you think you want.

wnick wrote: I am an electrician. 200 amp single phase is common and plenty for your house. From the main panel run a 1" conduit to the garage and put in a 60 amp sub panel. The only reason I would consider increasing the amperage is if the furnace and water heater are not gas but electric. I once put a 400 amp service in a house but that was 6000 square feet and a 4 car garage. As far as 3 phase for residential, it is extremely rare. I have a 100 amp ( that I have not yet changed to 200), a 60 amp sub panel on my second floor and a 30 sub panel in my detached garage. My house is 2500 sq ft with a basement, 2 central air units a pool pump and 2 kids with every light in house on and I am fine.

I'm not an electrician, but I used to sell to them. I was going to say, unless your house was really big, a 200a panel should suffice for anything you'd want to feed from it, nice to know I remember a little bit.

I would have though a sub with a main in the garage would be a good idea, but I'm curious as to what you, the professional, would say.

As someone mentioned, you might want to have the capacity to have a car charger if you chose to buy an all electric vehicle. My wife wants a Nissan Leaf at some point.

Does anyone know what is needed for a 220v home car changer?

I am also an electrician, this is is right.

You won't get three phase power without special conditions, so don't expect that. They would have to put a special transformer on the pole for you, and don't think that would be free.

wnick wrote: I am an electrician. 200 amp single phase is common and plenty for your house. From the main panel run a 1" conduit to the garage and put in a 60 amp sub panel. The only reason I would consider increasing the amperage is if the furnace and water heater are not gas but electric. I once put a 400 amp service in a house but that was 6000 square feet and a 4 car garage. As far as 3 phase for residential, it is extremely rare. I have a 100 amp ( that I have not yet changed to 200), a 60 amp sub panel on my second floor and a 30 sub panel in my detached garage. My house is 2500 sq ft with a basement, 2 central air units a pool pump and 2 kids with every light in house on and I am fine.

You would have to get the specs off of the charger. A cut sheet will tell you that, should be free from the manufacturer of your choice.

OldGray320i wrote:

wnick wrote: I am an electrician. 200 amp single phase is common and plenty for your house. From the main panel run a 1" conduit to the garage and put in a 60 amp sub panel. The only reason I would consider increasing the amperage is if the furnace and water heater are not gas but electric. I once put a 400 amp service in a house but that was 6000 square feet and a 4 car garage. As far as 3 phase for residential, it is extremely rare. I have a 100 amp ( that I have not yet changed to 200), a 60 amp sub panel on my second floor and a 30 sub panel in my detached garage. My house is 2500 sq ft with a basement, 2 central air units a pool pump and 2 kids with every light in house on and I am fine.

I'm not an electrician, but I used to sell to them. I was going to say, unless your house was really big, a 200a panel should suffice for anything you'd want to feed from it, nice to know I remember a little bit. I would have though a sub with a main in the garage would be a good idea, but I'm curious as to what you, the professional, would say.

100 amps seems to be the standard here. Mine is 100. Hard to add another 40 amps later with a sore toe from kicking yourself.

I looked up EV charging stations and it appears a 240vac, 30 amp circuit is pretty typical.

wnick wrote: I am an electrician. 200 amp single phase is common and plenty for your house. From the main panel run a 1" conduit to the garage and put in a 60 amp sub panel. The only reason I would consider increasing the amperage is if the furnace and water heater are not gas but electric. I once put a 400 amp service in a house but that was 6000 square feet and a 4 car garage. As far as 3 phase for residential, it is extremely rare. I have a 100 amp ( that I have not yet changed to 200), a 60 amp sub panel on my second floor and a 30 sub panel in my detached garage. My house is 2500 sq ft with a basement, 2 central air units a pool pump and 2 kids with every light in house on and I am fine.

^Agreed^

We have 200 amp service to the main load center, a 100 amp sub that handles an extension on the house w/ a small split HVAC system w/ heat pump and my little machine shop w/ a 5hp rotary phase converter, and the 60 amp sub in the garage. Main loads in the garage are either a 240 single phase 5hp compressor ~or~ a 185 MIG or 180 TIG machine.

When we built a new kitchen last year it got it's own 12 space sub panel and the electric oven got a run bac to the main load center.

So at this point there's the main and 3 subs and it's all clean and tidy.

4cylndrfury wrote: Thanks guys, I think I'm gonna go with a mix of the ideas here -70amp on a sub panel...hopefully will provide plenty of punch and expandability without adding too much $$$

Good luck finding a 70 amp breaker. I don't think they exist. Go with a 50 or 100 amp feed. You won't use close to either amount, trust me. Houses don't use much in the way of amperage, but they do however use a lot of circuits.