# Running a shop off a generator



## ladiesman217 (Aug 7, 2009)

Hey all, I know this has been touched upon before but I would like to hear some more opinions on this…

I luckily have a detached garage that is ~60 ft from the house. Unfortunately, it has a very weak 15A line to it. That's it. I cannot run a dust collector and saw at the same time..everything is dark and covered in dust at this point. I also happened to buy a PM 66 for a steal (full well knowing I did not have the power for this beast) and would love to get it running.

Now I spoke with an electrician and he quoted me $1400 to add a box, breakers, and dig and install the line to the garage to give me a 50 amp box. That's a lot of money to me at the moment (just paid for a headgasket job on my Subaru). I had the idea that I could buy a generator and use it to power the saws, dust collector, etc instead of paying for the electrician-oh, and I don't know how long I'll be living here + I only use the machines a couple hours a week at most with my job taking all the hours of the day.

So what's the verdict?


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## JAAune (Jan 22, 2012)

The biggest expense might be the digging. I'm not sure on that but when I got power to my shop I shoveled out the trench myself and did the filling as well. You might want to check to see how much the cost comes down if you do the same. No sense in paying an electrician $50.00 an hour to move dirt.


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## fussy (Jan 18, 2010)

Nope! No can do. $1400.00 may seem kinda high to you, but the price of a generator capable of handling the load you will apply with just a saw, lights and dc would far exceed that price. Then you have to add the cost of gas and the rather steady maintainance requirements of a gas generator. The homeowner units sold at big box stores don't have the huevos to pull the load without seriously underpowering and damaging your equipment.

Get other estimates, but If you're serious, get a 100 amp sub panel. 50 amps would be a bare minimum. If you find that too stiff, have the electrician install wiring from your house big enough for 100 amps, put in a 100 amp box (you can find them used all over the place. Lots of people upgrade 100 amp to 200) and buy only the breakers you need now. You can add circuits later ass you need, and you can read up and do that yourself, iof you feel confident and proceed according to code. The digging and labor would be the same, just higher cost initially for the wire to the garage. Good luck.

Steve


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## timbit2006 (Jan 6, 2012)

I have 60 amps in my shop and it works perfect. I used to have 30 and I was tripping breakers all the time.
With gas prices and the cost of the generator I highly doubt it would be more economical than re-wiring your shop.


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## patron (Apr 2, 2009)

worst case 
and a quickie

make a decent extension cord
(or buy a 10 gauge one)
and find a receptacle that can handle it
in the garage or house

with as little use as you are using it
switch from tool to tool as needed

a generator will eat you alive
and the noise will bring down the neighbors


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## HamS (Nov 10, 2011)

Dig it yourself, it is good exercise. There is no magic to electricity. You can do most of the work and then pay the electrician for the things an electrician is really needed for. I put in a 100 Amp box in my barn, I ran all the circuits myself and then paid the electrician to inspect and do the final hookup. I only ended up paying the electrician for 1/2 hour work. This job was 7 years ago but I think the total cost was under $150. My back paid a different price for the digging however. 36" is real deep if you are digging by hand. However, there is a certain oneness with the world when your back is protesting the abuse you have put it to. Proverbs 31:7 would seem to apply here


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## JohnMeeley (Jan 5, 2012)

Do the work yourself. Don't worry about how long you'll be there, you'll recoup expenses if you do sell. Go 100 amp sub-panel, the 1400 buck quote had more to do with labor than size of panel. Pay for inspection and certification. Go have a beer at the local pub, you'll find a licensed elec. to inspect and sign off on it.


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## renners (Apr 9, 2010)

Could you hire a mini digger for the weekend and do the trench yourself? (It might even be fun).


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## Manitario (Jul 4, 2010)

I just had a small (40 amp) backup generator installed: $5000. You won't find a cheap generator that will be able to handle the current draw of your tools. I agree with what the other guys said about the sub panel: go for 100 amps, 50 amps won't cut it.


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## DS (Oct 10, 2011)

I suspect if you dig the trench and drop in the conduit, the price will come down substantially.
Paying electrician rates to dig holes is silly IMHO. 
A weekend in your back yard with a shovel can save a lot of dough.

Pay him to do the electrical work. Do the rest yourself.


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## oxyoke (Dec 15, 2011)

I went with 100amp service in my shop.I bought a black& decker.. home wiring book from home depo and materials.My inpections went fine and I learned another valuable skill.


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## Bill1225 (Oct 31, 2011)

I live an hour away Ill give you a hand no charge. Hardest part is digging the trench if you wont go for a ditch witch, which would cost about $75


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## Dal300 (Aug 4, 2011)

If you want to run a decent shop, go for the 100a or better yet, have ConEd or whoever sink a new power pole and transformer.
Or…..

In most states and municipalities it is legal for the home owner to do his own work without a permit.

If you have enough power coming from your main breakers to handle it, I can make you a great deal on some #2 copper. Or I think I have enough 2/0 to make it 120 feet.

Here's the kicker… if you have a 200a service coming into your house and you add up all the circuit breakers, where are you going to get the extra power to run your shop? Are there 200a worth of breakers in the box? Is the line in capable of handling the loads you want to put on it?

Do you even know what the NEC requires for a service entrance in your area? How about the municipality?

Just randomly pulling power off your meter head is a prescription for disaster.


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## longgone (May 5, 2009)

I rented a trencher when I ran power to my shop from the house panel. Paid about $60 to rent it for half a day and dug a trench about 175 feet to my shop. Pay the electrician to do the rest unless you are sure you can do the witing yourself.


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## Grandpa (Jan 28, 2011)

I rented a trencher…maybe $50 for half day…. and did my own. I paid the power company to make the final connection at the meter. They installed a breaker at the meter and attached to my line. That was $175 for the panel at the meter and a metal conduit up my meter pole. We have overhead power on REC (Rural Electric Cooperative) and the remainder is buried to the house and shop. The cost of a gen set then the fuel to operate it is expensive. Then the power would be marginal. As far as running a drop cord, the 10 ga. wire would carry 30 amps but you would have to have a 30A receptacle to plug it into. Most are 15A for 110V but you can get 20A and 30A at supply houses. Then the long run will have an amperage drop….so you will be better off to rent a ditcher and buy a panel. Talk to another electrician or even the same electrician with a plan in mind.


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## BobM001 (Jan 8, 2012)

Here's a chart for wire size ampacity for insulated conductors.
Ampacities of Insulated Conductors
From this chart you'll see that for a 100 amp service you'll need to run #3 copper in conduit or #0 direct burial aluminum. If you install a sub panel you'll need 4 conductors. 2 hot, a neutral, and a ground connected at the panel. You might be able to get by with 3 if you drive a ground rod outside of the shop.
This chart will give you conduit size based on size of conductors. 
Conduit sizing is determined by using table C.8 NEC 2008
I would bump up a size just to make the pulling easier. That would mean 1 1/2" PVC for (4) #3 copper conductors. Have a "LB" pull ell at the outside of the main stucture. One where you come up out of the ground and penetrate the side of the building, and one where you go up into the bottom of the sub panel. While you have the ditch open run a 1/2" conduit for a phone line or intercom.

So a pair of 1 1/2" 90 deg sweeps, enough pipe to get you from "A" to "B". A couple 1 1/2" straight connectors. Let's say (4) 1 1/2 "LB" 90's and you're good to go.

Have your conductors laid out on the ground and mark the ends with marker tape. Red, blue, for the hot, white for neutral, and green for ground

Remember the "electrician's axiom". One wire, hook it up. Two wires, screw it up. Three wires, pack it up.

Like others have said you can rent a ditch witch for a half day and have it done in nothing flat. A whole lot cheaper than $1500.

Bob


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## DocSavage45 (Aug 14, 2010)

All great suggestions. Really depends on your abilities, learning curve and the electrician you work with? If you hire an electrician there is a permit and an electrical inspector who will sign off on the box.

If you are new to wiring, get a how to book from your local box store and buy the best electrical hand tools you can afford. Will save on your energy and you will find a use later for them.

There are different ways to go about running a line, and type of wire ( aluminum or copper)

If you are doing work yourself, like digging call to have the property maked for underground lines. Don't want to power auger into a line that cuts across the property. 

Get bids from more than one electrcian. Get everything in writing, I had an electrician "not" finish " the job. Don't pay until the job is signed off by inspector. Talk to each one, and ask for customer references.

You can lay heavy duty uv cable on top of the ground if it is frozen or you have snow, and attatch an outside power cut off if you are planning on moving soon? Then take it with you? Above all as with wood working safety first.

Maybe new generators are quieter than mine, but it is another noise factor on our precious ears. LOL
good luck


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## Grandpa (Jan 28, 2011)

My generator was used non stop' except to refuel and check the oil twice daily, during an ice storm. We ran it for a week and it cost about $30 a day to do that so you might need to add that into the mix also. It would probably be marginal for your shop.


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## ladiesman217 (Aug 7, 2009)

Everyone, thanks for all the input. Since the consensus is 100 amps, I think that's the best route to take.

Hams and Doc, you guys are right, I would save buckets of money digging it myself.

Bill, I'll PM you.

Thanks again, guys. This is such a helpful and insightful community!


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## ssnvet (Jan 10, 2012)

I built my house on a 500 watt Home Depot generator… Coleman Powermate with Briggs Advantech OHV 9 HP engine. Cost me $500 on sale back in the day.

Learned the hard way that these type generators have major corners cut in their electrical construction and market themselves to the unsuspecting public by the virtue of the motor…. i.e. Honda, Advantech, etc..

I think they play games with the electrical ratings, just as some do with the HP ratings.

Generator died a year and a week from purchase date…. you guessed it… one year warrantee.

Surprised and happy to say, Coleman paid to have it repaired. But I lost the use of it for two critical weeks.

Then later on, the masonry contractor needed to run a 16" tile saw, and was hesitant to do so on my generator. But I was so sure that 500 watts was plenty, that I talked him into it. The starting coil on his saw motor fried after a long days use and I had to pay for the repair.

Lesson learned… economy generators don't save you anything. And many of what we think are "top brands" just sell their name to put on someone elses cheap junk. I wouldn't settle for anything less than a 6500 Watt Makita if I was to do it over again. But that generator would have run me $1,200 back in the same time period.

If I had to replace this generator today, I'd go diesel…. but they aint cheap either.

Live and learn.


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## BobM001 (Jan 8, 2012)

Every generator on the market is rated at "peak" KW. The "continuous" is lower. The other thing is what type/quality power does it produce? A Honda motor on a POS generator can spell nothing but trouble. If you think you can run a flat screen LCD TV or your PC off it, you had better get a UPS for BOTH. People in ice storm situations that ran electronics off "dirty" power found out the hard way when their stuff "blowed up". Inverter type generators are the ONLY portable types that make clean enough power for the affore mentioned uses. They are the most economical fuel wise as well. The inverter "talks" to the engine to tell it how fast to run based on load requirements. The others have to run at 1800 or 3600 even if a light bulb brings it up to speed from idle.

On to "inrush current" of induction or brush type motors. An induction motor with have the "locked rotor" letter designator on the name plate or the stated LR current. The generator has to have that capacity. It's generally 3 times the "full load" amps.

Don't be intimidated by the task of doing this wiring job yourself. The dough you save and the confidence/skill set you'll acquire will be it's own reward. Above all *"TEST BEFORE YOU TOUCH"* Check to a good source of ground. No reading, you're OK. Those "chirp" testers will work too.

Check your state and local regs about a homeowner doing their own electrical work. Most states it's OK. There is plenty of info out there on the internet or in published forms to show you how to do the job PROPERLY. It really isn't that hard. Proper wire sizing, grounding, and use of ground fault devices are what inspectors look for. If you have questions all the NEC (Nat'l Electrical Code) info is on the internet. Stuff like the hot ALWAYS goes to the brass screw on a recepticle, neutral to silver, and green is ground. Staples every 18"-24" if romex is run on the surface. I believe that ALL recepticles in garages or out bldgs now have to be ground fault protected. Minimum height above finshed floor is 15" for any recepticle. The first recepticle in "run" of a circuit has to be a GFCI type. That can protect multiple recepticles. Up to 6 I think. 230V single phase doesn't fall under the GFCI regs. But the breaker, wiring, recepticle, and plug to a power cord have to match. Go with twist lock on 230V. Use plastic boxes where ever possible. They don't have to be grounded. Metal does with a clip/screw and it's own ground wire. Use deep boxes. They give you room to stuff everything in. If you use metal boxes wrap the switch/recepticle with tape so no bare connection can touch metal. "Back connected" recepticles/switches are OK if you have to tighten a clamp screw to make the connection. Otherwise bend a hook. ALL junction boxes have to be accessible. Don't bury one in a wall. If you know someone that has a right angle drill with the self feed auger bits, offer a case of beer to borrow it. You won't regret it.

If you're starting out fresh, run all recepticle circuits with #12 wire on 20 amp breakers. Don't skimp on quality of recepticles either. You can probably get by with #14 on 15 amp breakers for lighting. If you have a table saw, dedicate a separate circuit just for it. The same with any other high horse power load. Code states that you need to have a light above the panel and a recepticle within 2 ft.

Do a lay out of where you want recepticles, switches, lights, etc. Get a list of materials together and go to a reputable electrical supply house. If the guy at a HD or Lowes was a licensed electrician at one point then he can help you. Go where the "know" is.

Electrical installations aren't a "black art". Just a lot of common sense. Hell if I did it all by the numbers I wouldn't bother with an inspection. But it better be RIGHT!


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## TopamaxSurvivor (May 2, 2008)

Better see what your fire insurance company thinks about illegal, uninspected work.


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## ssnvet (Jan 10, 2012)

I wired my entire house, after having the panel, meter box and one outlet installed by a licensed electrician (which is perfectly legal where I live). I understand the simple stuff and am even collecting parts to build my own rotary phase invertor.

That said, when I built a pole barn 100' from house and wanted power to it, I planned on doing the job myself. So I solicited "how to" advice from a licensed electrician, an unlicensed (but very experienced) maintenance electrician, a "jack of all trades" maintenance guy, and the ever reliable error free internet. Each source gave me different instructions concerning ground rods and splitting the common and ground busses.

Burning down the house and having the insurance deny the claim because I incorrectly did the work was not worth the $$ it cost me to have a new, copper bus, 100 amp panel put in by a licensed electritian.

The guy who did the work was very particular about how the conduit connections were made, which was a detail I would have totally overlooked.

I dug the ditch and helped lay the conduit to defray the cost. And I'll wire the "owner expansion" circuits, just like I did in my house.

OBTW…. two licensed electricians have looked at the work I did in the house myself and both commented that I was much more fussy and neat routing the wires in the panel than they would have been.


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## BobM001 (Jan 8, 2012)

GOOD POINT! But is this gent's case being from New Jersey, all the above is MOOT. Found this whilst perusing the web for New Jersey Codes. Titled DIY Electrical Work in New Jersey

Looks he might be able to do the work, but only HIMSELF. No friends, family, or anyone else for that matter can touch a thing. ONLY THE HOMEOWNER. Then there are the "routine maintenance" provisions.

I now can see the issue of location and regulation. Maybe the $1400 isn't such a bad deal to not have to deal with all the bureaucratic BS.


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## Grandpa (Jan 28, 2011)

I still didn't see anything that says the homeowner can't dig a ditch. I think the question here is do you own the home or is this a rental?


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## BobM001 (Jan 8, 2012)

You can't even pump your own gas in New Jersey!


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