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How many amps does your shop need?


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#1 Drott-150

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Posted 13 December 2005 - 10:44 AM

I'm going to build a pretty big workshop on my lot (about 45' x 85') including a living space inside and plan on having a decent array of welders and machine tools along with normal things associated with a home - i.e. HVAC and possibly electric heat for the living area (about 1500 sqft), washer/dryer (all electric), general lighting, and maybe a Jacuzzi in the future. The large shop space will be heated with wood and or oil (no AC), so that shouldn't be factored.

Any ideas what level of service I should get (amperage wise)? They offer 200-350 amp service at a standard rate. Anything over 400 amps requires a load letter and a riser diagram (whatever those are) from an electrician. But apparently if I have the letter and diagram I can get 400 amps and over for no extra charge...if I properly understood the field rep yesterday anyway.

I need to decide here real soon, and as always big $$$ are at stake, so any advice from you experts would be real helpful. Thanks in advance!

#2 muduc

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Posted 13 December 2005 - 11:28 AM

I work in the construction industry commercial and some residential, and this is my recommendation but by no means am I an electrician or electrical engineer. Typically a 200 amp service will run a normal household and a descent sized garage. This gives you ample power to run all major appliances, and have 100 amps dedicated to the garage with one 220 plug in the garage. You mentioned multiple welders...I get the impression you are looking at a mini machine shop. In this case you are talking at least the 350 amp service. Just my opinion...trying to help. It's always better to have more than you need than not enough.

#3 gilligan

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Posted 13 December 2005 - 11:31 AM

How long do you plan on working in this shop? Is three
phase available? In the long run 3 phase is cheaper, so I have been told.
Keep in mind I now nothing about electricity, but I am from the school of
thought that you over build now because at some point in time you will use
those resources later. Really depends on what your short/long term goals
are. Are you going to be doing any of the work yourself? Are you going to
start up a buisness at this location?

This topic will probably be a hot one & may give you
more questions than answers!

Good Luck!!!
Gilligan

#4 junkdude

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Posted 13 December 2005 - 03:51 PM

200 amps is plenty. 100 will work if you don't run the big energy
hogs at the same time ie. not welding while the wife is in the
hot tub. BTW I had one of those big tubs it could blow a 50 amp
breaker with all the pumps and heaters running, Just a big waste
of electricity and water.

#5 Drott-150

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Posted 13 December 2005 - 04:22 PM

Thanks for all the advice so far, let me clarify a few of the questions brought up. I don't plan on having a business per se, but I do envision having a pretty well outfitted machine shop. I plan on having a nice arc welder (Mig/Tig/SMAW) capable of light and heavy welding, a lathe, milling machine (or two), shaper, grinder, bandsaw, drill press, and maybe a few other powered tools as the need arises. But for the most part I'll be working by myself, I won't have "employees" or anything, so it would be rare for more than one machine to be running at the same time. Although there may be times when someone is helping me, or that I might be running an automated CNC process on a mill while I work at another machine. Or maybe have something in a sintering oven while I work at another machine. So I suppose there are situations that could arise where a few machines are running simultaneously, but certainly not all at once as might occur in a commercial application.

Thanks so much for the help, I'm in "I'm my own general contractor rapid decision mode" right now!

#6 magicmikey

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Posted 13 December 2005 - 04:31 PM

One thing you might do is add up the biggest items that will be running simultainously. That might include the "residence" if you are willing to work through dinner. :D
mike

#7 W.K.TEDDYBEAR

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Posted 13 December 2005 - 04:33 PM

AM TRING TO GET AHOLD OF DAD(ELECT.DESIGNER-COMMERCIAL) TO TRY TO FIND OUT WHAT HE THINKS.
UNTILL THEN
WITH THE POS. OF ELECTRIC HEAT I WOULD THINK 200 AMP IS PUSHING IT. DAD HAD OIL HEAT AND REPLACED WITH HEAT PUMP WITH ELECTRIC BACK UP AND HAD TO HAVE SERVICE UPGRADED TO 200 AMP. HE USES NO GARAGE TYPE EQUIPMENT JUST HOUSEHOLD LOAD. SO FOR THE TIME BEING I WOULD THINK MINIMUM OF 350 AMP.BUT ON THE OTHER HAND THE POWER TO MILKBARN IS ON 50 AMP BREAKER AND I HAVE NOT BLOWN IT, YET! HAVE A LARGE FREEZER,7HP.60GAL.COMPRESSOR,MILLER 120/240 WIRE FEED,225 LINCOLN,BUT IF A WELDER IS ON I TURN THE COMPRESSOR OFF, IF I NEED AIR AT SAME TIME I HOOK UP 5HP 220COMPRESSOR TO AIR LINE TO KEEP PRESSURE IN BIG COMP. UP.THE 7HP TAKES 52AMP FOR START UP BUT IT WILL START AND RUN WITH 30 AMP SLOW BLOW FUSES FOR SHOP MOTORS AND HEATING SYSTEMS WITH OUT BLOWING FUSES.
I ALSO AM NOT AN ELECTRICANN OR AN ELECT. DESIGNER OR ANY OTHER QUALIFING OCCUPATION,I HAVE DONE A FAIR AMOUNT OF ELECTRICAL WIRING AND DID SPEND ABOUT 6 MONTHS WORKING AS ELECTRICANS HELPER BACK IN LATE 70'S MAINLY COMMERCIAL(WHY I PREFER CONDUIT OVER HOUSE WIRE).
THIS 20 YR OLD MODULAR HAS 200 AMP PANEL 90AMPS FOR FURANACE,40 AMP FOR STOVE,30AMP DRYER,25AMP HOT WATER,PLUS LIGHT AND OUTLETS, WASHER AND 2 KITCHEN OUTLETS ARE 20 AMP REST AND LIGHTING ARE 15 AMP.
LOAD LETTER IF I UNDERSTAND DAD RIGHT SOUNDS LIKE LETTER STATING AMP DRAW OF ALL EQUIPMENT TAKEN FROM ALL EQUIP./MOTOR TAGS,AND FIGURING X WATTS OF LIGHTING TO X SQ FEET AND OUTLET WIRING,ETC.BASICLY NEED DESIGNER/ELECTRICAN TO DETERMINE TOTAL LOAD DRAW YOU WILL NEED FOR YOUR BUILDING,RISER DIAGRAM SHOWS SERVICE ENTRANCE AND ALL PANELS CONNECTED TO IT,AS I UNDERSTOOD DAD.SUGESTION WAS YOU NEED AN ELECTRICAL CODE BOOK (IF YOU CAN UNDERSTAND AND FIND WHAT YOU NEED IN IT (CAN BE COMPICATED TO THE UNKNOWING-FROM MY EXPERIANCE TO UNDERSTAND/INTERPITE)OR NEED TO CONSULATE ELECTRICAN,SUGGESTS THAT 350 AMP OR 150 AMP PANEL MIGHT BE HARD TO COME BY BUT MIGHT BE ABLE TO CHANGE MAIN BREAKER TO 150 AMP/350AMP(IF EXISTS-HE DON'T RECALL AND MY CODE BOOK IS NOT AT MY FINGER TIPS CURRENTLY)IF CODE/POWER SUPPLIER ALLOWS IT-MORE QUESTIONS NOW TO FIND OUT.
I THINK YOU JUST OPENED A CAN OF WORMS,GOOD LUCK, WILL TRY TO FIND SOME OF THIS IN CODE BOOK AS SOON AS I CAN GET TO IT,HOPEFULLY WE HAVE AN ELECTRICAN ON HERE SOMEWHERE THAT CAN GIVE YOU BETTER ANSWERS.DAD HAS A LOT OF THINGS GOING ON THE NEXT FEW DAYS AND IS NOT ABLE TO GET ON COMPUTER FOR AWHILE,PLUS HE NEEDS TO JOIN RP FIRST.
TAKE CARE,HAVE A GOOD ONE BEST OF LUCK,!
PAUL

Edited by W.K.TEDDYBEAR, 13 December 2005 - 11:33 PM.

photo-127.jpg MY GRANDSON GETTING HIS SECOND RIDE AT 2 1/2 YEARS!

G-PA'S 1951 SUPER A WITH BELLY MOWER&A-193 PLOW,THAT NEEDS FRONT LIFT PARTS
1985 CHEV. EL CAMINO(MOM'S BABY) 1981 GMC 2500 WITH A STOP AT EVERY GAS PUMP 454.
Janay is doing well! thank you all!
CLEAN FOR 12 YEARS(on 8-13-13)SOBER A LOT LONGER! :- )
God grant me the SERENITY to accept the things I cannot change;COURAGE to change the things I can; and WISDOM to know the difference.
Living one day at a time; enjoying one moment at a time; accepting hardships as the pathway to peace;taking, as He did, this sinful world as it is, not as I would have it:Trusting that He will make all things right if I surrender to His Will; that I may be reasonably happy in this life and supremely happy with Him forever in the next. Amen


#8 MadReferee

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Posted 13 December 2005 - 05:31 PM

I have basically a similar setup for power needs, lathe, 3 welders, grinder, plasma, big compressor, mill with another on the way, electric washer/dryer, all electric kitchen plus the entire house. I have a 200 amp service and it is more than enough.

My basement shop is wired on a 20 amp circuit for the outlets, the lathe, compressor and milling machines are on a 30 amp circuit and the welders are on a 60 amp circuit. I have NEVER popped a breaker in 25 years and I don't make a habit of running more than what a circuit can handle. I have never worried about running shop equipment while anything else in the house was being used.

You will be just fine with a 200 amp service. Put the money you will be saving by not going to 350 amps (it's overkill and have you priced out a 350 amp box? big $$$) into another shop machine. :rolleyes:

#9 Rawleigh99

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Posted 13 December 2005 - 05:57 PM

I have 400 amps in my barn/shop with an apartment over it. I have a 2.5 ton heat pump, 7 hp compressor, 5 hp tablesaw, 15" planer, 8" jointer, mig welder, stickwelder, dust collector, two fridges, instant elec water heater (3 - 50 amp circuits for that). The compressor will dim the lights in the apartment when it comes on. I tried to get 3 phase installed, but I had to prove a 15HP min load to the power co. If you intend to run any decent machine tools you should try to get 3 phase. You need to look at phase converters both as to price and HP capacity. Factor the cost of the converter against the cost of 3 phase installation. You can get some really cool big old machine tools that are 3 phase reasonably cheap. The 220 stuff is smaller and more expensive to buy and run. Just my two cents, but its always cheaper and better to put in adequate service up front than to go back in a couple of years and try to upgrade.
Rawleigh

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#10 hogman_2002

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Posted 13 December 2005 - 11:04 PM

I'm gonna agree with Rawleigh99, if you can, get 3 phase. Especially if you plan on running lathes or vertical mills. We built a similar shed alittle over a year ago(50x80). We ran 220 single phase to it with 200 amps. But less than a year after I had the shed wired up we wished we would have ran 3 phase to it. The main reason we didn't was because it would have cost $3per foot, thus it would cost over $1500 to get 3 phase to the shed. It seems cheap now. You'll be suprised how many things you'll find that are 3 phase.



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