Stupid Electrical Question


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I've got a 3HP cabinet saw ordered and have an electrician buddy coming over to wire me up with some 220. While he's here I'm also going to have him wire for the jointer, planer and dust collection.

 

So here's the stupid question since I've never owned DC before...

 

I only have 100 amp service in my house right now, and a 50 amp going to the garage...do you think that would be enough to run two 220 machines at once (on separate breakers), or do you think that would trip my main?

 

Thanks for the advice!

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Eric,

Your DC won't do much good for you if it is not running while you're using the tools. I start mine DC (220 btw) then start my tool, finish what I'm doing with the tool, turn off the tool, then turn off the DC 30 sec or more after.

I have my DC on a different breaker from my other 220 lines for my other tools. My shop is wired with a 60 amp feed into a subpanel with other 220 and 110 circuits. Since it is just me in the shop, at max, I run the DC, a tool, an air cleaner and lights at one time.

I have seperate circuits for each 220 machine (5 total) and 4-110 circuits (one for each wall) and 1 for the lights. You can not exceed the total amp draw of the machines on any one circuit. You should be able to run the 2 220 machines on seperate circuits and not trip your main. The exception would be if you have your electric stove on (50 amp), your elec hot water heater (30 amp) or air conditioner (40 amp) and lights and other stuff on at the same time. But you may not have electric utilites other than the air conditioner?

Tim

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I'm also in the process of finishing the basement, so I'm having a sub-panel installed for all the wiring for the basement and the garage. It will be installed on the basement wall next to the main panel, but it's just a short trip through the bandboard to get to the garage.

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Thanks Tim, that's the answer I needed. I have all electric utilities except the furnace, so I'll just tell my wife there's no cooking or laundry while I'm in the garage...maybe I'll make her an old timey washboard and clothesline for my first project on the new table saw. :D

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Yeah you want the dust collector running while you are running the saw.

 

Right, or you could install a subpanel in the garage and run separate circuits from there. The economics of it depends on how far and easy it is to get wiring from the garage to the main panel in the house, and how many spaces are available in the main.

 

It should be no problem unless your service is already on the edge of overload.

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Your buddy should be able to answer your Q's in more detail but if I can remember my math for ohms law I might guess that you could blow your main even with a sub-panel if you max your usage out in the house and the shop at the same time. That is just not very likely to happen though. The usage in your house will dictate how likely it is though because most times you will only ever run dust collection and one other tool at a time plus lights and recharger's maybe. So if you max out a sub panel it blows. Your house has 100 amps so you likely don't have electric heat if you do or have some heaters there for the shop in winter say that is when you "might" run into problems. Wife doing laundry while cooking the thanks giving bird baseboard heaters on in the shop running the saw and DC... you get the idea :)May want to wait until the holidays are over in that case. 90% of the time you will be using much less than the max in your shop. Let your buddy have the last word on it though and if you don't understand what he says right away give him a couple beer and pick his brain until you do it will be worth the beer in the end.

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I talked to my buddy about it quite a bit, and when I told him what I had in mind he said I should be okay with the 100A service except in scenarios like you mentioned, Joe...but he did recommend that I eventually upgrade to 200A service. So maybe one day I will. I was really just wanting to know whether or not I should run a separate leg for the DC, and I think I got that answer.

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Eric, because I'm doing some work on the house. My L&I guy gave me a site to do my load calculations. I'll try to get that and post it sometime this weekend. He said it was an easy tool to use.

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Put a 100 amp sub panel in (they are cheep) for future machines,

run the size of wire for 100 amps use a #3 or #2 gage wire ,

to code you can use a breaker that is lower I would use 60 amp

until you change the main panel to 200 amps.

" Don't Bond The Sub Panel"

(2) Hot (Black)

(1) Neutral (White)

(1) Ground (Green 6ga)

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Probably the best thing to do is try to keep your load balanced. And the easiest way to do that is use 240V where possible, at least on all the big loads.

A/C, DC, lighting, and table saw.

Okay, LIGHTING, but that's only 120V, yup. What I did is split the lighting in my shop over 2 dedicated breakers, one on each phase. Two reasons for doing it, one is to balance the load, but, if one of the breakers where to pop, or a phase where to go, I would still have light in the shop.

You do need to independent breakers, so, AFAIK, all code dictates separate switch boxes. But that is not a problem, I have several switches as I like the granularity in switching. So I only turn on the lights I need.

Tom

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Okay, LIGHTING, but that's only 120V, yup. What I did is split the lighting in my shop over 2 dedicated breakers, one on each phase. Two reasons for doing it, one is to balance the load, but, if one of the breakers where to pop, or a phase where to go, I would still have light in the shop.

I like that idea! I'll probably leave the garage lights as they are, run off the main panel. Whoever planned the electric in my house must have been high the day he did it, because the ONLY outlet I have in the garage right now is in the same leg as my two upstairs bathrooms (on the OTHER side of the house...figure that one out???). So any time I'm running the compressor or contractor saw, even circ saw, and the wife goes to blow-dry her hair...pop.

I'll be running the new 110 outlets off the sub-panel for sure, and maybe I'll put one of the lights on it, too, just for fun.

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