200 amp service enough for house + shop?

[Slyder]

(Tried searching but wasn't able to find an answer based on my situation...)

My new-to-me house came w/ a 36 x 48 detached shop that while structurally complete is neither wired nor plumbed. Originally I was planning to have a second meter added just for the shop, however my local power co. advised that the pedestal serving my house would need to be upgraded; that combined w/ the cost of a new meter would run me $1800, and that's not even to get wire back to the shop.

My electrician friend figures I'd be marginally OK to run a subpanel from the house (200 amp service) back to the shop, but I want to get a better sense if I'll have enough capacity going that route.

The house is 2700sqft, gas heated via heat pump plus a furnace. All appliances are gas w/ the exception of our washing machine. Our well is shared w/ the neighbor and runs off a separate meter so it's not on the 200 amp circuit.

In the shop, beyond the usual low draw items (lights, drills, etc) I'll have a 220v compressor (22.5 amps) and a 220v MIG welder (27 amps). I very rarely use the welder. There is an unfinished loft upstairs that I'll eventually turn into a game room (TV, microwave, etc).

That being said, will I be able to successfully run my house and shop off the same 200 amp service? If so, how close would I be to maxing it out? I realize that having a separate meter would be ideal but I'd like to avoid the $1800 and extra monthly charges if they're not really necessary.

Thanks in advance,
- Chris

 

[lametec]

In short, yes.

All depends on your usage, obviously. I doubt you weld and, use the compressor, watch TV and pop popcorn at the same time.

 

[pattenp]

How much breaker space is available in your main service panel? What's the number and amp of breakers in the main? The odds are you will be fine with running power to your shop off the main in your house.

 

[Rosco]

I would say yes, as long as you know there will be limitations and also you need to have 2 open slots on the 200 amp panel available.

 

[Slyder]

In short, yes.

All depends on your usage, obviously. I doubt you weld and, use the compressor, watch TV and pop popcorn at the same time.

Right, I'm sure I'd be able to overload it if I really wanted to intentionally max it. I'm mostly curious if I'll even be approaching the upper bounds based on standard usage given the devices/appliances I'm working with.

How much breaker space is available in your main service panel? What's the number and amp of breakers in the main? The odds are you will be fine with running power to your shop off the main in your house.

My main panel is more-or-less full already but my electrician advised that he could replace many of the standard size, low amp breakers w/ their smaller (peanut?) equivalents in order to free up room for powering the shop.

 

[pattenp]

As long as you don’t crank up the marijuana grow lights in the attic at the same time you’re welding and the compressor is running you’ll be ok.

 

[hfdff]

I'm not an electrian but as long as you have space in your main panel you should be ok with a subpanel. I recently wired my metal building w/ an 100amp sub panel and havent had a problem. I also have 200amp main service.

 

[Grinder Bill]

Unless you plan on running several of your high current devices at the same time you should be good to go. And you may be able to run a second cable from your side of the meter to a second panel in the shop, which is what my setup is...

Rural location, originally a 50/75A 220V breaker at the pole, upgraded (free) to 75/100A 'cuz it was tripping mid-summer when the house AC was running full time/dryer on/septic pump kicks in.

1600sqft house panel has a 200A main breaker and feeds the 220V rangetop, 2 ovens, AC, dryer, and septic pump. 110V circuits include furnace, boiler, suntan bed, washer, dishwasher, 2 fridges, 2 freezers, 3 big screen tv's, and 2 block heaters in the winter (go figure... a 2 car garage, big shop and big barn and the trucks live outside year-round....) We use a lot of juice.

1600sqft shop has a 70A main breaker. 220V loads include mig, tig, metal lathe, milldrill, air compressor, deep well water pump and dugout/stock waterer pump located about a km away.

Have yet to trip the new 75/100A pole breaker (3 years), but the lights in the house flicker when I'm tig welding 1/4" aluminum, which isn't often.

 

[theoldwizard1]

The house is 2700sqft, gas heated via heat pump plus a furnace.

So you have an electric heat pump and a gas furnace ? Does the heat pump have a resistance heater built in ?

I would limit the sub-panel to about 70-80 amps. You probably could get by with 50 amps. Even with the compress running and a 10" table saw and vacuum, you should have plenty left over for lights, TV, etc (maybe not the popcorn popper) on 50 amps.

 

[Slyder]

Have yet to trip the new 75/100A pole breaker (3 years), but the lights in the house flicker when I'm tig welding 1/4" aluminum, which isn't often.

How much do the lights dim when you fire-up the girl in your avatar?? Dayum!

So you have an electric heat pump and a gas furnace ? Does the heat pump have a resistance heater built in ?

The house was built in '06 w/ a gas furnace, but also wired for a heat pump. The original owner added a heat pump the next year, so the furnace now simply circulates air from the heat pump and acts as a backup. I'm not too familiar w/ the heat pump yet.

Thanks for the responses fellas, sounds like adding a sub-panel off my house panel will not be a problem... unless I start welding while sitting in a hot tub while my wife dries our laundry and pops popcorn as she waits for me to get electrocuted.

- Chris

 

[toyotadriver]

So you have an electric heat pump and a gas furnace ? Does the heat pump have a resistance heater built in ?

I would limit the sub-panel to about 70-80 amps. You probably could get by with 50 amps. Even with the compress running and a 10" table saw and vacuum, you should have plenty left over for lights, TV, etc (maybe not the popcorn popper) on 50 amps.

You can install a heat pump with a gas backup...it's called a dual fuel furnace. Works good.

For the OP, the 200 amp service will do what you need. I have an all electric house and it has 200 amp service. It also has a heat pump with electric strips. I also run a welder and air compressor. I've never had an issue. You'll be fine unless you add a lot more high power draw tools in your shop.

 

[ForceFed70]

If it get's below 15*F in your neck of the woods, you need to have a backup heater as heat pumps do not work efficiently below 15*

200A should be lots. Most homes in my area only have a 100A panel to start with.

 

[Cobra6]

You can probably get by with this -
My house is ~2950 sq. ft, but part of it was an addition with a subpanel, so I have 3 electric heat pumps, plus a pool with a pump that runs 24/7 in the summer.

All the electricians said ~3000 sq. ft was a good general rule for the top end of 200 amp service.

since I built a 24' x 36' shop which will have a large compressor, 18K BTU TTW heat/AC, lift, water heater, etc., I upgraded to 400 Amps. 400 A service was already there from the utility company. I have a 200 A panel for my house, a 100 A panel for my pool pump and crawler, and 100A panel to my garage.

 

[jvitez]

The obvious answer: do a proper heat loss calc. There, I had to say it. LOL!

But seriously, do some math first. It's a lot cheaper than redoing work, or forever saying "coulda, shoulda, woulda....."

Do a proper NEC load calc for your house. Now add up everything in the garage you would conceivably use at the same time, and anything you might want to add later. Calculate everything in watts, not amps. Now add the two. It will show you exactly if 200 amps is enough. It probably will be.

Watts=volts x amps, so 200 amps x 240 volts=48,000 watts total capacity. By the info you give and some quicky calculations, if you're not planning on using the welder and have the compressor running at the same time, a 60 amp subpanel would probably suffice at 14,400 watts total, even with a future games room addition. That is unless you're planning any electric heat. Nothing ups the demand like electric heat.

 

[StaggeringGoat]

As long as you don’t crank up the marijuana grow lights in the attic at the same time you’re welding and the compressor is running you’ll be ok.

My new 40x60 shop condo only has 125 amp service (3 phase), and it was a former marijuana grow shop with TONS of lighting and cooling equipment. All the neighbors have pretty big businesses going on in their units and they only have 125 amp service as well...

 

[W_A_Watson_II]

I have 400 Amps to the House, and a separate 400 Amps to the Shop, but that wasn't the original intent when we built.

Was supposed to have one 400 Amp Service to the Meter on the House, then feed the House with 200 Amps, and the Shop with 200 Amps. When they got to the burring point to feed power to the shop, they had failed to pre-order the proper size buried cable, and I was limited to a smaller size, and with the 300+ foot run was facing a voltage drop with it.

So I left the 400 Amps already ran to the House in place, and had a separate feed/Meter installed for the Shop. Was going to go with 200 AMPs, but for only the cost difference in the meter base, decided to go big. Never can have too much can you?

 

[StaggeringGoat]

Think of it this way, 200 amp service is 48,000 watts. That's enough to power 800 60w light bulbs. Do you ever use that much power at once?

 

[Aceman]

I'm not an electrian but as long as you have space in your main panel you should be ok with a subpanel.

I'd be so lucky if it were only that simple.

 

[volleyball]

I think your service with a 100a sub to garage is plenty but a couple of questions. How many people in the house? How many using high power equipment? If you have 2 teen girls in different bathrooms, you better do your welding after they are done.
Are your bills high now? Mine are low so I don't worry about overload. Not likely I will be in the hot tub while welding and running the sand blaster.

 

[Falcon67]

Think of it this way, 200 amp service is 48,000 watts. That's enough to power 800 60w light bulbs. Do you ever use that much power at once?

Are you sayin' he's 800 bulbs short of a full load???

 

[Jack Olsen]

I have a 2400 sf house. Air conditioning is on all summer. There are big screen TVs in the house. I weld. I run a lift in the garage. The whole deal is done on 100 amp service. Everything runs at the same time and I've never had any issues (except my freakin' electric bill ).

 

[Trey T]

agree! 200A box is a lot of power.

In short, yes.

All depends on your usage, obviously. I doubt you weld and, use the compressor, watch TV and pop popcorn at the same time.