Garage sub-panel. 100a? 200a? How about 125a?

[plowhog]

I am putting in a detached garage and current plans are to set a 100a electric subpanel. It will connect to a 400a subpanel at the house. (Existing 200a panel presently being upgraded to 400a.) In the thread about my garage, many here advised to upgrade the garage subpanel to a 200a model, for just a "small increase in wire cost."

I asked my electrician about this. He said "don't do it." According to him, if I put a 200a subpanel in the garage, it would require using the "big breaker" slot at the top of the 400a panel. Using that "big breaker" slot in the 400a panel would then limit the 400a panel servicing the house to only 200a. To meet code I need more than 200a for the house.

He did say there is sort-of a happy medium. He said I could set a 125a panel in the garage instead of a 100a. With that config, it uses a regular breaker in the 400a panel which doesn't limit the house amperage in the same way. But I get a little extra "oomph" of power to the garage.

I'm new to this. Does that make sense?

 

[Deere Dude]

All I know is I put in a 100 amp service in my garage and works fine. A 100 amp breaker from the main house was simple.

But, it all depends on your usage at one time. I have a 50 amp plug for my welder, a bunch of 20 amps outlets for shop tools, a 30 amp for my camper, a 220 volt for an AC.

The thing is, I never run a drill press and weld at the same time. I am the only one running power equipment in the garage. The only two things that may take place at one time are the welder and the battery charger for the camper.

A 100 amp with a dozen spots for breakers will work fine, unless you have a few people working in there welding and using another high amp draw tool at the same time.

 

[jaxs]

Ask the electrician about burying wire capiable of 200 amps and installing the largest breaker that will fit "small breaker slot". That leave's the 200 amp option open should code change later and meanwhile cause less voltage drop to garage.

 

[RNeumann]

I am putting in a detached garage and current plans are to set a 100a electric subpanel. It will connect to a 400a subpanel at the house. (Existing 200a panel presently being upgraded to 400a.) In the thread about my garage, many here advised to upgrade the garage subpanel to a 200a model, for just a "small increase in wire cost."

I asked my electrician about this. He said "don't do it." According to him, if I put a 200a subpanel in the garage, it would require using the "big breaker" slot at the top of the 400a panel. Using that "big breaker" slot in the 400a panel would then limit the 400a panel servicing the house to only 200a. To meet code I need more than 200a for the house.

He did say there is sort-of a happy medium. He said I could set a 125a panel in the garage instead of a 100a. With that config, it uses a regular breaker in the 400a panel which doesn't limit the house amperage in the same way. But I get a little extra "oomph" of power to the garage.

I'm new to this. Does that make sense?

Not everyone was suggesting a 200a subpanel in the shop. Glad your electrician is bringing you back to a more reasonable amperage. 200a amps of 120v (100a breaker and feed) is more than enough.

 

[Stimw]

You don't say what you plan to run in the building. ??
At my last property I had a 200 amp main and I ran electric to a 40' X 50' shop. I put in a 100 amp panel and used the building for a business.
In 18 years I only had the 100 amp main trip once and that was when I was welding and a friend was using my Plasma cutter with the 5 hp air compressor going also.

 

[2458n]

That is good to see your electrician is working to keep you up to code, and up on power. Money well spent.

 

[Industrial Toys]

That sound insane! A 200 amp garage panel. Used to be, whole farms had 60 amp service. People usually think they need more then they do, as they don't usually use several heavy loads at once.

 

[plowhog]

My motor home draws close to 50 amps with everything running, which can happen on a hot day (3 a/c units, residential refrigerator, etc.) I designed a 2nd exterior/outdoor 50a hookup so our friends can park their motorhome adjacent to the garage when they visit.

For freeze protection, there are four ceiling mounted qmark heaters. Those are 220v/5kw each, not sure how that equates to amps.

I also have a 220v compressor (not sure of amps,) electric water heater (30a), car lift (30a), 2nd interior RV hookup (30a), 220V linear amplifier (not purchased yet,) and ceiling fans. Plus lights, plugs, etc.

Of course not all things would run at once. The motorhome a/c is high draw, but it would never be running at the same time as the high draw qmark heaters.

 

[jaxs]

My motor home draws close to 50 amps with everything running, which can happen on a hot day (3 a/c units, residential refrigerator, etc.) I designed a 2nd exterior/outdoor 50a hookup so our friends can park their motorhome adjacent to the garage when they visit.

For freeze protection, there are four ceiling mounted qmark heaters. Those are 220v/5kw each, not sure how that equates to amps.

I also have a 220v compressor (not sure of amps,) electric water heater (30a), car lift (30a), 2nd interior RV hookup (30a), 220V linear amplifier (not purchased yet,) and ceiling fans. Plus lights, plugs, etc.

Of course not all things would run at once. The motorhome a/c is high draw, but it would never be running at the same time as the high draw qmark heaters.

The spare amps doesn't sound insane to me. I say go for it.

 

[truckdiagnostics]

Put 200 amp in the shop or at least make sure you have the option! You may not use it but what about if you have to sell it. what will the next owner going to do. Things change if you don't have to 200 amp and you need it what are you going to do. will you be able to add more latter. I thought I would never use the 200 amps I have, I have the panel maxed out. I run a 50 amp powder coat oven, welder, 5hp compressor and lift. with only two in the shop, it is not hard to be using all those things at once. Then there is the lights, well pump and plasma cutter. it does not take much and adds up fast.