I’m looking to geet a generator for my new shop to run my planer, table saw etc. until I can get power run out to my shop. It will be awhile.
For all you electrically minded folks, how large of a generator shiould I get? the largest load I will be running is 220V on a 20 amp circut (my planer and table saw) and Ithe lights will be running off it when the saw is running….
Is a 5550 watt generator with a 25 amp circut going to do the job or do I need to go bigger?
thanks
Replies
5500W is a litte small for a 25 A circuit... unless the Gen. is only putting out 220V ......is this the rating on the generator you are considering ? That size is adequate for many loads but
A few things to consider .
..The length and gauge of the extension cord(s) , ...
....Finding a cord with the proper ends....
...How many lights are on ..
....what kind of lights..
the inrush to your saw /planer might cause problems with the lighting...
..the lighting may cause problems when the motors try to start,
some simple manipulation of the loads, will fix it
a running saw draws less than a working saw.....
I apologize if you are aware of these things .........
one rule of thumb for motors on gennys.is
2.5KW / HP...., so.....7500W = 5HP........
one rule of thumb for motors on gennys.is 2.5KW / HP...., so.....7500W = 5HP........
Your example doesn't match your rule. If it's 2.5KW/HP, then 3HP should get you 7500W. Your example works out to 1.5KW/HP. Which do you mean?My goal is for my work to outlast me. Expect my joinery to get simpler as time goes by.
ooops.......somebody fire the secretary........;>)5 X 2.5 =12,500KWthanks
Sorry to get in at the last of the conversation but Where do you get 12,500 watts from 5 HP. I have been considering a generator for my 24 HP Diesel tractor. Northern has a compatible generator but it delivers only 13,000 watts. That is about two HP per 1000 Watts. Am I missing something?
,
2,500 W per HP to START an induction motor..... I did not mean to imply output of a motor, sorry ...! there would be as you say, less KW per HPthe 2.5 KW is from conversations with start-up techs and engineers on the Gen jobs I have worked on......but they are foucused on "Stand-by " power not "portable " ;>)from my last job.......,
An interesting discussion.
I live off the grid with 100% solar and a Propane 11KW Honda Propane Generator, derated to about 9KW due to our altitulde 8000ft.
I bought a 20in powermatic planer with 5hp single phase motor.
My generator won't run it because it draws 62 amps when it starts.
The solar system is all 110v.
I am in a dilemma cause a 20kw diesel generator is going to be $12000 new. Out here, Colorado Rockies, I am unlikely to find a used diesel, and this elevation results in some very cold nites. Diesel fuel most likely looks like lime jello.
Any thoughts on how to get around this dilemma?
Stef
is the solar stored or do you run the genny at night ?I'm sure you considered something like this already?http://www.electricgeneratorsdirect.com/catalog/product_info.php?cPath=36_129_132&products_id=387&osCsid=7aa4a538a65c7ad1bac00dfdf1d660bb
Edited 2/2/2006 1:02 pm by maddog3
Thanks for your prompt reply.
We do store solar with 16 batteries.
The generator is for days when there has been insufficient solarization.
I was not aware of that generator. I can't ascertain if it is suitable for the protracted usage ours gets in the winter, but it looks like it is, given that it is water cooled.
Thanks for the pointer.
Stef
1. Haul the planer out into a shed and hook it up to a gas engine.
2. Get a bigger generator.
3. Use a smaller motor to bring the planer up to speed then turn on the 5 hp main motor, this will eliminate the starting current surge. Some engineering would be involved in this obviously.
John White
Shop Manager, Fine Woodworking Magazine
Folks who sell solar panels like Real Goods or Arizona Light and Power (sp?) are familiar with the engineering that goes into building a power system and have good guides (obviously oriented towards solar but generator backup is also part of these systems) On that topic, have you looked into solar rebates in your state? Here in California they have very sizeable rebates on new solar systems which makes it much more economical - wouldn't handle all your load but might enable you to size the generator smaller.
The size of the circuit breakers isn't what counts, it is the current draw of the equipment that will determine the minimum size of generator that you need.
Start out by figuring out what the most likely maximum load will be, then go from there. The maximum load would be something like the lights, the furnace or AC running if you have them, a dust collector if you have that, and the power draw of the largest power tool in the shop. Add those figures up and you'll have a number to start sizing your generator.
I have a lot of experience running generators. They are a workable alternative to grid power if you absolutely can't get power lines to the shop, but they are expensive to run, noisy, require regular maintenance and fueling, and can wear out surprisingly fast if you buy a homeowner's model running on gasoline. If you can get grid power to your shop you are better off getting that installed if at all possible.
John W.
Did you ever run the propane ones? I worked for a utility (phone), and we replaced all our diesel ones at our remote switch offices, with propane. Ended the gelling problems in the winter. They came on line slower, but that did not matter to us, we used the to run power inverters. Just curious.
Interesting question. I have that same size generator. I got it about 15 years ago when we had a bad ice storm in Va and we were without power for a week. I backwired it into the house (threw the main to protect the linemen), and ran most of the house with it. That rating is max rating and the more load you apply the harder it works. Mine watts grunt down when you approached 4000 wats, but would run just fine. It holds 5 gallons of gas and would run (depending on load) about 11-12 hrs. The oil had to be changed every 40hrs of use. I suggest you go higher (if you can afford it). At least a 10kw. Are you not going to want to run a light or two while you run your saw? You don't mention the draw rating of your saw either. If it's a big cabinet saw, you will have an issue. You can do it, but first add up all the Amps of the equipment that would be on at the same time. Also remember that generators have two ratings. The largest wattage is the peak draw and the lower is the continuous rating (at least this was the case back when I got mine). They are loud, but they are supposed to be outside anyway. Finally you might check out used welders (the pull behind kind) they work great and have a 50A plug for power. I had a friend that picked one up used cheap and spent a little TLC and had a heck of a generator. It may be worth your while to talk to the power company and see about the cost to run a service to shop, might be cheaper. Good luck.
PS If you do use one, don't forget the ground!!!!!
Edited 1/23/2006 9:58 am ET by bones
...."I backwired it into the house (threw the main to protect the linemen)...."lets not promote this idea OK !!
Hey, at the time there was not power for a good 30 miles. There was not time to buy and install a double throw generator switch. I had to drive for 2.5 hrs just to find a generator. I had a good friend who work for the power company pass on what I was doing. For all those out there, use a proper throw switch. This is one that will not permit power to feed the house with the main power on. The reason is you don't want power going back out on the line. There is my disclaimer. I never forget walking out on the deck and all you could hear is the hum of generators.
Try this link.. May help?
http://www.gohonda.com/sizing.html
H.C.: What a great oppertunity to go 3 phase!! It won't be cheap but you will be able to get 3 phase machines and use them with out the phase converter run-a-round. After you get regular power out to the shop you can only run the generator for your three phase machines and in a power failure. I've been dreaming of doing just that for some time now. Duke
The Bill of Rights
December 15 1791
NRA Endowment Member
LEAA Life Member
CRPA Member
Hobble creek,
No you won't be happy with that 5500.
You really need about 10,000. I'd say that if you can live with the noise a 6500 would just about work if you were careful.
for about the price of those cheap disposable portable generators if you shop around you can find an older diesel generator that the phone company or a city replaced with propane/LP
Most have very few hours on them and were replaced because the ease of keeping them fueled up plus there is actually a requirement that they are replaced every 10 years..
Used at a shop a 10KW diesel generator will last you decades with nothing more than oil changes.plus provide the house with back up power.
If you want free or very lowfuel costs then make a deal with your local resturant to come and get their fryer fat.. They currantly pay to have it hauled off and I know a few guys who not only get a months worth of fuel but a couple of burgers tossed in the deal..
diesels run fine on fryer fat and even smell like popcorn doing it! You'll have to make a tank to hold it and a great filter system. (plenty of info on the internet on how to do this) and a way to go pick it up.
If you are far enough north you'll want to keep it in a warm area so it doesn't soidify You could also get an old electric forklift battery freshen it up* and use that thru an inverter.
* Freshen it up mean you remove all the acid and water from each cell (save it in glass) let the sediment settle out Tip the battery over and flush out all the lead suffate. Once nothing but clearwater comes out and no more sediment is left in the battery I then put all the acid and water back in careful not to suck up any of the lead sulfate. Older batteries need a little more acid so I buy enough for a car battery and that's usually enough to top off those big forklift batteries... Check the PH to confirm.
I helped a friend 10 years ago do this and he's still using a battery that was considered junk to run off the grid He does have a diesel (fryer fat?) as his back up and when he needs three phase or 220 for something..
Frenchy,
That's some good info. I'll start looking for a old diesel generator. You don't know of any websites that auction them off etc. do you?
Go talk to your local generator guy.. Talk to your local phone company.. check with the maintinace shops of medium to big cities.
Caterpillar is big in that and often get tradeins.. web sites would only be of value if there was a flood of them.
One thing about diesel gen sets is you have to keep them under load. I once rebuilt a diesel motor for gen set & welder combination & we ran it under load for a while to seat the rings & the people that had it just let is set & idle & the rings didn't stay seated ( this was the original problem that the gen set came to us for).
If you run a diesel gen set this way the rings won't seat or stay seated.It has to be made to work hard for at least a medium>medium hard duty cycle if you can't do that consistently don't waste your money because one day you'll just find your motor blowing blue oil smoke. Remember a diesel motor is an entirely different situation then a gas motor.
If your gen set is going to be running at an idle for long periods of time as I suspect it will for a hobby shop don't buy a diesel gen set.
We tried to trade them for a gas gen set welder to start with after we got the set back the second time they decided that they wanted the gas gen set welder.
When we got the gen set back the second time to seat the rings we set the welder up with a real heavy rod & cranked the welder setting up & started cutting 5/8" scrap metal & it didn't take long to seat the rings. But it doesn't always happen this way & could be a lot more expensive to repair.
Edited 1/30/2006 9:08 pm by OB
Edited 1/31/2006 12:01 pm by OB
Edited 1/31/2006 12:05 pm by OB
Edited 1/31/2006 12:06 pm by OB
I use a gen for my Air compressor , plainer, tablesaw for years and I wish I had spent just a little more for a Honda and with more than 5500 and 25 amp. 6 years old with No problems, but look into buying Honda, much quitter. I heard their more dependable.
Furniture builder, GR,Mi
I am guessing that in the 14 years since the post, any problems will have been sorted out...
This forum post is now archived. Commenting has been disabled