What size generator does a man really need?

  • Advertise with us

« back to Power Tools, Hardware and Accessories forum

Forum topic by oldwolf posted 05-30-2010 08:43 AM 8888 views 0 times favorited 20 replies Add to Favorites Watch
View oldwolf's profile


100 posts in 3283 days

05-30-2010 08:43 AM

Topic tags/keywords: generator workshop electricity electrical advise

For several reasons I am relocating my workshop to my parents land and the rather sizeable steel shed they have in the back yard. I have all the standard toys, Rigid contractors table saw, drill press, an old delta rockwell joiner, lathe, miter saw, benchtop bandsaw, and hand power tools with a dust collector coming in the near future. Currently the power attending the shed is a buried extension cord from an exterior plug in to the house. It only needed to run lights and the occasional circular saw before. Now I will be taxing it.

My dad and I were discussing going in on a generator together, because it would be a cheeper way to go than to have a professional come in and run real wiring and a fuse box to the shed. Today we looked a little at them in my grizzly catalog and we both decided we both have no true idea what we are looking at what would be enough, what would be underpowered and what would be overkill. Not knowing makes it difficult to plan or budget.

Being generally prudent guys we figured mid-range on what we saw would probably work, a 5500 Watt generator, but is something that size truly needed to run, lets say a table saw, 1 1/2 hp dust collector, and maybe a radio at the same time? We just don’t know how watts relates to what is needed. I do know that I have popped a 20 amp breaker with the table saw from time to time when it’s gotten bogged down in some wood.

we are looking for some help and education on the issue from real people, I could go to a store and listen to a salesman tell me whatever and not know if I should believe him or not, help us make the right choice

Thank you

-- Oldwolf -

20 replies so far

View Pete_Jud's profile


424 posts in 3778 days

#1 posted 05-30-2010 09:40 AM

Is this just for standby, or for every day use? Makes a big diff. I have a couple of gensets. I live on the wrong side of a river that we have had a couple of a 100 year floods in the past couple of years. I can take the power People a couple of days to get the juice back to the place. If you are off the grid, I might go with a 10 Kw unit to power the shop. I know that now you have only with the table saw, and DC, and lights. But you don’t know what you add next. A 7.5 would be the min.

-- Life is to short to own an ugly boat.

View iamwelty's profile


259 posts in 3141 days

#2 posted 05-30-2010 01:49 PM

I think you should hard wire your shed… a buried extension cord sounds slightly terrifying… you may want to rethink that too.

-- There is a fine line between eroticism and nausea...

View Sawkerf's profile


1730 posts in 3094 days

#3 posted 05-30-2010 02:51 PM

Derek -
You should talk to an electrical contractor who could help you determine the amount of service the shop would need – now and in the future. Knowing that, you can run some cost comparisons between running wiring from the house to the shop v.s. buying and installing an appropriately sized generator.

-- Adversity doesn't build reveals it.

View richgreer's profile


4541 posts in 3100 days

#4 posted 05-30-2010 03:00 PM

Maybe this is just me, but I know that hearing a generator run all the time I am in the shop would greatly diminish the enjoyment factor.

-- Rich, Cedar Rapids, IA - I'm a woodworker. I don't create beauty, I reveal it.

View BTKS's profile


1986 posts in 3490 days

#5 posted 05-30-2010 03:28 PM

Having lived at the whims of generators, I only like having them around emergencies. Keep the freezer froze and a few lights on.
The upfront cost of wiring the shed could very easily be recouped in fueling, maintenance and accessories. The other con to full time use of a generator is spikes and dips in what is called dirty power. Personally, I never plan on running my heat pump on a gen without some sort of buffer / filter in place.
If it is for occasional use, do what you think is best. OH, I’ve never used a propane or natural gas powered generator, that could be a huge difference in noise and maintenance but probably a big difference in cost.
You may also find out what it will cost if an electrician runs the underground and service panel and you run the branch circuits and mount the boxes then the electrician making the final connections. This option can really cut labor expenses.
Hope this helps and good luck with your new shop. BTKS
Sorry about jumping in and out.
If your power is going to be convenient, you’ll still be running all the branch circuits within the shop. Otherwise, you’ll have a constant battle of tangled extension cords and snares laying on the floor. Again, best of luck.

-- "Man's ingenuity has outrun his intelligence" (Joseph Wood Krutch)

View bent's profile


311 posts in 3694 days

#6 posted 05-30-2010 03:38 PM

it may be intially cheaper to buy a generator than run wiring, but what about the cost of operation? i’ll bet in the long run it’s cheaper to rewire.

to figure out the power consumption of your equipment, it’s: power = voltage (110V) x amperage (usually listed on the motor). also, the breakers you have you supplying the circuits need to be 125% of the load.

View ND2ELK's profile


13495 posts in 3799 days

#7 posted 05-30-2010 03:45 PM

I would think wiring the shed would be cheaper in the long run.

God Bless

-- Mc Bridge Cabinets, Iowa

View Steve Peterson's profile

Steve Peterson

377 posts in 3108 days

#8 posted 06-01-2010 04:48 AM

If it’s close enough to run an extension cord, then it should be close enough to run real power. The size of the wire depends on the max current and the length. Look up “wire current carrying capacity” to see what size wire you would need for your situation.

Things get better at 220V instead of 110V. An 8V drop at 220V is equivalent to a 4V drop at 110V with the same size wire if the current is balanced on both wires. The 8V drop would occur with twice the current. The voltage is also double, so the power is 4X higher with the same size wire. The cost is that you need 4 wires instead of 3.

I can run everything in my garage from a 50A breaker. This includes a 5HP table saw and a 5HP dust collector, plus lights and some random small loads. You might be able to squeeze into a 30A breaker with smaller tools, but compare cost differences between 30A and 50A wiring. If it is close, go with the bigger wire. Your tools will be happier and you will have room for more stuff. You might want to run a small heater or air conditioner to make it comfortable to work.

I suspect that the cost of running a generator over the long run is much greater than the cost of the wire. Both have an upfront cost. The generator might burn through a couple of gallons of gas per day, but the same amount of power from the grid is probably less than a dollar.

Like everyone else, I recommend running wires.

-- Steve

View a1Jim's profile


117117 posts in 3602 days

#9 posted 06-01-2010 05:08 AM

I agree with getting it wired

-- wood crafting & woodworking classes

View lilredweldingrod's profile


2496 posts in 3132 days

#10 posted 06-03-2010 08:31 AM

By the time you get the fuel bill for the generator, you will wish you had hired a sparky to run a line out there.

View Steve Peterson's profile

Steve Peterson

377 posts in 3108 days

#11 posted 06-03-2010 04:10 PM

Rob, 5 gallons of gas per day would add up really fast. At $3 per gallon that would be over $5000 per year. Wire should be looking a lot better.

-- Steve

View Ben Martin's profile

Ben Martin

34 posts in 3234 days

#12 posted 06-03-2010 07:55 PM

I’ll agree, if an extension cord can reach, you are probably better off running proper wiring. The generator might initially seem cheaper, but the dirty power will rack up additional costs. You’ll end up burning a motor or 2 eventually from a bad power spike, or brownout, or you’ll need to invest in a fairly pricy line conditioner to clean up the power. Fuel adds up fast too, the noise gets annoying, if not for you, for anyone else around.

You are setting up a shop that I expect you plan to use for a while. Don’t thnk about the cost of wiring as an expense, think of it as an investiment. If you folks want to sell the property, having the shed wired properly will make it worth that much more.

View loupitou06's profile


137 posts in 3351 days

#13 posted 06-04-2010 05:53 AM

If I may,

I just add a sub panel installed in my garage in order to stop popping breakers and make room for some new 220V tools coming.
So from my main panel, I ran ~60ft of 90A/220V cord (the expensive one) to a 60A sub-panel. And from there I’ve installed 4 220V plugs and 4X4 110V plugs.
The total cost of material was ~400$ (from the big box stores).
The quotes to get it installed started ~600$.

Just like Steve was saying, at 3$/gallon, you will burn (literally) the cost of the installation in 333 gallons, around 66 days !

I hope this will help you make your choice.

Good luck on your project

-- 100 fois sur le metier remettez votre ouvrage

View TopamaxSurvivor's profile


18288 posts in 3701 days

#14 posted 06-04-2010 07:15 AM

They are a bit spendy to run on a daily basis.

You need to dedcide what is the biggest motor you will run with the dust collector. If you are tripping a 20 amp breaker on 120 v, the table saw is probably 1 or 1 1/2 horse. At a minimum, you need a 6kw generator, a 7.5 would be better.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View robertp's profile


18 posts in 2937 days

#15 posted 06-06-2010 10:00 PM

How far to the Shed? If you read a few books you could wire it yourself legally if your building department allows homeowner permits. Otherwise you could do it illegally or go with something temporary like 2 cables of 10ga romex in some pvc conduit going to a couple 20 amp gfi in the house; that would give you 2 decent 120v circuits. That would be the cheap way but better use the GFIs as by the time the current gets out to the end of the hot wire on a long extension cord it might just as soon go through you and into the ground as opposed to making that long trip back to the house. Another idea depending upon the set up might be to get a new service to the shed. We did that on a property we own that is spread out along the road with the house at one end and the building at the other. I have a 5000W Generac and despite what it says powerwise it can’t run a conveyor belt 120V 18amp conveyor belt that does ok with house wiring and a 100’ 10 ga extension cord. To have reliable power I think you would need a bigger generator than you are contemplating. Otherwise pretty much what everyone else said.
Good luck

showing 1 through 15 of 20 replies

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics