What amperage to update to?

[-Brent-]

Fellas, got some questions about updating the electrical in the house and garage we're buying. I'm a novice when it comes to this stuff so any help is appreciated.

Anyhow before we move in, we're updating the electrical service from 70 amp and adding a sub panel in the garage. The electrician recommended 125 in the house and 80 in the garage but after speaking with a few people they said to bump it up to 200a (house) and 100a (shop) to allow for future updates.

That being said, I want the garage amperage to be sufficient to handle any piece of equipment I grow into. I've got a decent selection of fab tools now but I'll be adding a plasma cutter, welder, a larger compressor, 4 post lift, etc. as time goes on. While I know that they all won't be running at the same time I want to be able to add shop items without any limitations, electrical service-wise.

As far as the home amperage with his recommended 125. I couldn't see any reason not to go with it other than the three men I've spoken with (my dad, the city's bld inspector and a friend of mine) all said to go to 200 amp.

The electrician is my friend and I know he's got my best interests in mind but he's pretty adament that I'll only need 80 in the shop and 125 in the house so I am conflicted.

Any of you have an opinion?

Thanks in advance, Brent.

 

[chickenhauler]

There's not many houses that actually need more than 100 amp, and most garages would be fine with 60 amp. But since you are already upgrading, and do plan to add the mentioned toys, I would go with 200 in the house and 100 in the garage.

If you will have separate meters at both the house and garage, I'd just do 125 at the house, and 100 at the garage.

 

[-Brent-]

Thanks. No seperate meters. The house is getting the meter and from there we'll go to the house and shop panels... I believe.

 

[Stuart in MN]

I suppose it varies around the country, but these days a 200 amp residential electrical service is almost universal for new construction. If I was going to go to the trouble and expense of updating my house, that's what I would get.

A 100 amp subpanel in the garage fed from a 200 amp main panel in the house is nice, but 90% of the time, even with all the equipment you have planned, it's going to be overkill. If you have the budget, go for it, but the 80 amp your friend is suggesting (or even 60 amps in my opinion) will probably be more than adequate.

 

[MrMark]

I don't know why you wouldn't go with the 200 amp if doing a replacement. It's not much more, maybe no more if the POCO supplies the wires to the new panel. Does your house need it? Of course not, you probably could do fine with a 60 amp panel unless the house is huge and you are in an area with heavy AC and you don't have natural gas. The house has been working all these years on 70 amp panel, which is really 140 amps with a fully diversified load with the two hot legs, so yeah, 200 amps is tremendous overkill, but it is the defacto standard and it is CHEAP.

 

[Mad40er]

We just had our service upgraded to 200amp from 100.

We have a 200A main panel at the meter, and a 100A sub in the house.

I will be feeding a 100A panel to the garage which will be fed from a 70A breaker.

My electrician said not much more is needed, as even with a compressor and welder almost hitting that, there is not much chance of running everything at the same time.

Chances are that your service provider already has provision to supply 200A to your house, but if you want 300A, they may charge you silly money to provision that.

 

[theoldwizard1]

A 100 amp subpanel in the garage fed from a 200 amp main panel in the house is nice, but 90% of the time, even with all the equipment you have planned, it's going to be overkill.

One thing people are forgetting is that a plasma cutter REQUIRES air pressure, meaning both pieces of equipment will be pulling power at the same time.

That being said, I think your fine with 200 for the house and 100 for the garage.

 

[Falcon67]

Having done this a couple of times with smaller panels, you'll be money and hassle ahead to just go 200/100.

 

[-Brent-]

Thanks, all.

I don't want gross overkill but it sounds like 200a in the house w/ a 100a, while it's more than I need, is not a gross overkill plan. I don't plan on running a full blown machine shop but I want to be able to support any machine that finds its way into the garage.

I've heard a few times that things won't be used at the same time but I think about my old, shared shop rental when the heater, compressor, and plasma would run at the same time. If it wasn't the plasma, it was a chop saw or lathe and the other stuff kicking on. I don't know the actual draw of those things but I know took some juice to operate them and that's what I want to be prepared for.

Again, thanks. You're all helping me get some better understanding.

 

[ddawg16]

I have 200A at the house with a double breaker feeding the garage with 50A.....prior to that it was 30a....NEVER tripped it......

Well....except when I ran the ground rod through the PVC pipe connecting the garage to the house....at least the circuit breaker worked and my son who was holding the ground rod did not get shocked....

 

[rodm1]

Having done this a couple of times with smaller panels, you'll be money and hassle ahead to just go 200/100.

I agree it won't be much more just extra on materials. At minimum go 125/100. I did a 200/200 in mine I wont ever out grow it.

 

[Steevo]

I used a 100A panel in my shop, not because I will need 100A of service at any given time, but because it had the room for all the breakers needed to get all of the circuits I wanted.

I have a lathe, mill, drill press, bandsaw, MIG welder, water heater, parts washer, etc. etc.
Probably only ever run one or two of them at any time.

 

[jvitez]

At a minimum, do 200 amps to the house. I agree with the other replies. Once going to the expense and hassle of upgrading, why not do a bit more? It's a tiny increase in cost over 125 amps, and will forever stop the "coulda, shoulda, woulda"s.

Now the garage? Add up the wattage, not amperage, of everything you think you could ever see running at the same time. Divide by 240. There's the minimum amperage you need to supply. 60 amps is already 14,400 watts, 100 amps is 24,000 watts, or one monster amount of power. The big addition is always electrical heating. Do you every foresee adding it? If not, 14.4 KW may be enough. Do the calculation, and don't guess!

 

[-Brent-]

You're correct, Jvitez, guessing is no good. I talked to a friend with similar tools and hobby. We spoke about my machinery and what I plan to add and he said no less than 100a in the shop.

He runs 200a to his house and 200a in the shop. While a lot of people scoffed at him running 400a to the meter he says that not once has he had a spike in his draw, which was what used to give his wife fits at their old place when looking at the electric bill.

I'm not planning to go that big but I like that theory.

 

[madstat]

I'm going to side with Steevo, it seems the limiting factor here is not so much amperage but it is SPACE. With every update to the NEC it seems more and more things require dedicated circuits or changes to circuit design. I have a 100amp service to my house and my panel is chocked full simply to meet code for dedicated circuits to washer, dryer, dishwasher, disposal, microhood, furnace, sump pump, smoke alarms etc... all of a sudden there is no room in my panel or further upgrades. I don't think I ever use close to the 100 amps at any time but there is no space at all in my panel.

 

[MrMark]

I used a 100A panel in my shop, not because I will need 100A of service at any given time, but because it had the room for all the breakers needed to get all of the circuits I wanted.

I have a lathe, mill, drill press, bandsaw, MIG welder, water heater, parts washer, etc. etc.
Probably only ever run one or two of them at any time.

That is a good looking panel, you should be justifiably proud if you did that. I have to ask though, why all the red wires? Better than black?

edit: Is that your way of doing 240V? Trying to remember what I did. I think I just taped the white black so that I had two blacks going in to the double pole breaker. I have to look now. I think I like your way better.

 

[MrMark]

I see the feeder neutral is a black wire taped white. There is some rule on that where you can't do that for under a certain size wire. They want you to buy a white wire. I'm going to guess 4 awg and under you can't tape white black. Since this is a 100 amp panel you probably feed it with 3 AWG. So the rule is not broken, all correct?

 

[Norcal]

I used a 100A panel in my shop, not because I will need 100A of service at any given time, but because it had the room for all the breakers needed to get all of the circuits I wanted.

I have a lathe, mill, drill press, bandsaw, MIG welder, water heater, parts washer, etc. etc.
Probably only ever run one or two of them at any time.

Why didn't you flip the panel so the feeder cables are not so excessively long? Not trying to pee in your cereal but that panel is made for top or bottom feed, the main breaker operates side to side* so no code reason not to. It just makes for a cleaner job.

* The NEC does require if a breaker is mounted vertical, the "ON" position must be up which is why sideways mounted panels like they do in Canuckistan is not allowed.

 

[jvitez]

I'm going to side with Steevo, it seems the limiting factor here is not so much amperage but it is SPACE. With every update to the NEC it seems more and more things require dedicated circuits or changes to circuit design. I have a 100amp service to my house and my panel is chocked full simply to meet code for dedicated circuits to washer, dryer, dishwasher, disposal, microhood, furnace, sump pump, smoke alarms etc... all of a sudden there is no room in my panel or further upgrades. I don't think I ever use close to the 100 amps at any time but there is no space at all in my panel.

Just for clarity, the OP asked about total load. Panel rating is another matter entirely, just so others reading this don't get confused if they're new to electrical issues.

You can run any size wire with the appropriate breaker to any panel, as long as you don't exceed the panel rating. A 10/3 feeder protected with a 30 amp breaker can feed a 100 amp rated subpanel, no problem. It can feed a 4 space subpanel, or a 40 space subpanel just as well.

So there are 3 things to consider here:

1. total load the OP might use at the same time. This tells him what size wire he needs, and what size breaker needs to protect that wire in the main panel.

2. Knowing the amperage of the breaker/wire feeder, he needs to buy a subpanel rated for at least that load. Going over is no problem.

3. Number of spaces in the subpanel. This is relatively independent to the first two. You need to know how many circuits, but also how many double pole breakers you'll need. As always, leave yourself room for expansion when you're upgrading. I bought an 8 space panel for my basement workshop, then realized I needed 10 spaces after changing my plan, so I bought a 16 space one.

 

[StaggeringGoat]

He runs 200a to his house and 200a in the shop. While a lot of people scoffed at him running 400a to the meter he says that not once has he had a spike in his draw, which was what used to give his wife fits at their old place when looking at the electric bill.

He must not be using as much power then. The number of amps of service you have has absolutely nothing to do with your bill.

I had 100 amp power in my old shop and NEVER came close to using it all, and that was with a ridiculous amount of lights and electric heat.

 

[-Brent-]

He must not be using as much power then. The number of amps of service you have has absolutely nothing to do with your bill.

First, I've got to admit all this lingo is not common to me. So, my explanations of what was said may be "off." The electricity I understand and can use is in machine repair. As well, I worked on rough and finish carpentry and never took the time to understand the idiosyncrasies of electrical. I'm regretting that now.

Thanks for the conversation and input, folks. I'm getting it, slowly. As well, it should be said that there's a LOT of misinformation out there. So, for noobs, like me, out there be prepared throw out hearsay information.

 

[Jkaz]

I have a 200a House feeding to 100a garage. Everyone I talked to said it was more than adequate. My setup is heated/insulated and the previous owner had a limo repair business. I'm sure he had some heavy equipment. You should be fine.