Is 100 amps enough power?

Justin C · Jun 13, 2011

Hi guys i am still planning on my new garage and after talking with my electrition he says i should be ok with running a 100amp panel for the garage. I will be running my air compressor 230 volts hope to get a new one soon, I just plan on using power tools. So what is everyone else using for power 100,125 150 or 200 for there power?

paullie · Jun 13, 2011

100 should be fine, it's what i got

Motofixxer · Jun 13, 2011

100a should be plenty for most cases. Unless your running everything all at the same time. You know like your mig welder, tig welder, compressor, lift, table saw, miter saw, powder coating oven, base board heater, G73 240v heater, oh and the A\C to cool down all the heat produced from the previously mentioned multitasking. :bowdown:

Think of most households have been 100a for many years, how often are there problems, not very.

vhol5 · Jun 14, 2011

A well equipped shop, with just a few 220v circuits, will fill the panel fast!
Leave room for growth...

bobadame · Jun 14, 2011

I ran my shop for years off a 60 amp breaker from the house. This fed into a 100 amp box in the shop. I ran a 220, 5 horse power compressor, an old Miller gold star tig welder a mill, a couple of lathes, grinders a drill press etc. Just not all at once. I never once tripped the 60 amp breaker.

larry_g · Jun 14, 2011

Justin C said:
Hi guys i am still planning on my new garage and after talking with my electrition he says i should be ok with running a 100amp panel for the garage. I will be running my air compressor 230 volts hope to get a new one soon, I just plan on using power tools. So what is everyone else using for power 100,125 150 or 200 for there power?

Justin
Asking this is like asking is 100 hp enough power. Yet you don't give any information of what you powering. Some of us have full machine shops and large panels some of us have a single 20amp circuit. The only way you can get a decent answer is to list out what you will have in the garage needing power, and an estimate of how many powered machines will be running at any one time. Otherwise you will get a bunch of replys that hit all over the place.

lg
no neat sig line

NUTTSGT · Jun 14, 2011

My garage has a 200 amp service that is separate from the house. Why? Because it was a business before I bought it, so I left it that way. If I was running service for a new garage without the possiblity of having it separate, I'd be good with a 100 amp service.

Now, one thing you may want to keep in mind, if you have Geothermal or are using all electric, an electric instant-on water heater, you may want to consider what the load is in your house, enough room (to grow)in the panel for your 100 amp garage service. You may want to consider a separate service for your garage taking into consideration what you are doing out there. I don't know what the power company in your area is like, cost for electric, allowable meters on your property or cost to put in a second service.

But it is something to keep in mind.

BTW, my service to the garage costs me about 30-38 dollars a month, depending on what I'm doing out there.

fefarms · Jun 14, 2011

a 100 amp feeder circuit or a set of 100 amp service conductors is plenty for a one man shop not using electric heat or serious amounts of air conditioning.

In contrast, in my opinion, a 100 amp PANEL is too small. Considering the number of specialty circuits you may want, and the wire bending space you'd need for welder or compressor circuits, why fight with a small panel? At the big box stores there's a negligible difference in price between a 100 amp and a 200 amp panel.

If the garage is supplied by a feeder, overcurrent protection for the feeder is at the source and you can freely use a larger main breaker panel. If the garage has its own service conductors, then you'll need a separate disconnect to protect them, if you use a panel with a main breaker larger than the ampacity of the service conductors.

Falcon67 · Jun 14, 2011

I plan to feed my new shop with 70~100A but I'll probably use a 200A panel so I have plenty of circuits. The 100 and 150s may be a little short.

FWIW - I have LOTS of power tools. I did a test in the old shop, with more machines running than one person would plus lights and 230V compressor running. I barely made it to 45A draw. That was running the mill, lathe, drill press, grinder, every light in the place and the compressor all at the same time. Electric heat full blast added 20A.

gatchel · Jun 14, 2011

100 is fine. That's what I used also (fed with a 90 amp breaker...)

My buddy was a garage with lots of lighting, a welder, compressor, lift, plasma cutter, bench grinder, brake lathe, computer, etc....all fed from a 60 amp breaker in the house and has never tripped the breaker in 15 years.

Steevo · Jun 14, 2011

I put 100A service into my 24x40 shop, and filled it to the max with convenience outlets for 120v and 240v all over the shop, plus lots of lighting.

I'm not worried about exceeding the 100A capacity, since I can only operate one power tool at a time.

thrifty bill · Jun 15, 2011

+1. 100 AMP service is fine, but use a larger panel with lots of circuits.

Cuda · Jun 15, 2011

What size and type wire would I run for an underground feed of less than 100 ft from the main? Again with the 100 amp feed.

mrb · Jun 15, 2011

i want one of the new Square D 84 circuit panels....

Worsedog · Jul 3, 2011

mrb said:
i want one of the new Square D 84 circuit panels....

More is better

.

I also have 100 amps, but I use a 200 amp service panel for the circuit space. I have 2 1/2 tons of a/c, a 250 amp mig welder, 5 hp compressor and of course the assorted smaller stuff and have yet to pop a breaker. :3gears:

Motofixxer · Jul 5, 2011

Cuda said:
What size and type wire would I run for an underground feed of less than 100 ft from the main? Again with the 100 amp feed.

Simplest and cheapest that I have been told is SER which is Alum 2-2-2-4, sometimes known as Mobile home service cable. There appears to be some discrepancy in the main breaker for it. Sounds like 90a main for it is the consensus. But you might want to contact your local inspector, they will be the one making the decision.

Falcon67 · Jul 5, 2011

Cuda said:
What size and type wire would I run for an underground feed of less than 100 ft from the main? Again with the 100 amp feed.

I don't have the table handy to look at copper, but my 100A service will have to be 1/0 aluminum per the new codes.

Aceman · Jul 5, 2011

mrb said:
i want one of the new Square D 84 circuit panels....

I'd rather have two 42 spacer's than one 84. That's a lot of wire to stuff in one panel(and keep neat), plus if a breaker ever goes bad and takes the buss with it, I'd rather replace the guts in a smaller panel.

I tried to buy a Siemens 60-something-space panel about 2 years ago, but I think they told me it only came in a bolt-on.

Aceman · Jul 5, 2011

Motofixxer said:
Simplest and cheapest that I have been told is SER which is Alum 2-2-2-4, sometimes known as Mobile home service cable. There appears to be some discrepancy in the main breaker for it. Sounds like 90a main for it is the consensus. But you might want to contact your local inspector, they will be the one making the decision.

Please don't get that confused.

SER is a 4 wire cable with an outer sheath(looks like a big gray Romex) used most of the time indoors for feeding subpanels.

Mobile home feeder looks like quadplex(like aerial cable feeding a home) which is just 4 individual conductors twisted up like a candy cane, it has no outer sheath like SER. This is the stuff for underground.

Falcon67 · Jul 5, 2011

If I read table 310 right, you need #1 copper for 100A service and 1/0 aluminum for the same. How it is to be run will determine the type of wire used. I plan to consult an expert on that before I buy (not the one working the product aisle) a foot of anything. 2/2/2/4 is 75A feeder cable per 2008 and above. I'm not a Holiday Inn Expert but I know there is a big difference per the NEC between SERVICE cable and FEEDER cable ratings. 2/2/2/4 might be OK for a 100A mobile SERVICE but it's only 75A for a FEEDER. Somebody check me on that.

PS - Found a Square D panel that has a 100A main and 24 slots - it comes as a Value Pack with the main, 3 20A breakers and 2 30A doubles. Model # HOM24M100VP.

Norcal · Jul 6, 2011

Aceman said:
I'd rather have two 42 spacer's than one 84. That's a lot of wire to stuff in one panel(and keep neat), plus if a breaker ever goes bad and takes the buss with it, I'd rather replace the guts in a smaller panel.

I tried to buy a Siemens 60-something-space panel about 2 years ago, but I think they told me it only came in a bolt-on.

2-42 circuit panels will be a lot easier to wire then 1-84 circuit panel, it will be the same width tub w/ 2X the circuits, stuffing 10 Lbs of **** in a 5 Lb bag.

BTW I prefer bolt-on

mrb · Jul 6, 2011

meh. i like 84 circuit panel. maybe put wireway next to it nippled into the panel with branch circuit conduits landed in the wireway. if it werent for the cost of AFCIs (and copper now) it would be interesting to wire the next house with one circuit per receptacle or two.

and yeah i prefer bolt ons too.

Is 100 amps enough power?

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Super Moderator

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member